MM
martin.mazurowski@drehmoment.de
Thu, Mar 30, 2023 6:28 AM
Dear all,
I have a problem here, I think I am missing something and I can't understand
what.
I made a modal analysis of a structure and then it was tested - the
correlation between test and FEA was ok.
Nevertheless, a mode was "not found".
The structure is supported on guide carriages and is held in axial direction
by a ball screw. The stiffness of these parts is represented with a
bushing-like element.
I suspected that the missing mode (at 90 Hz) is some kind of rigid body
motion due to the stiffness of the ball screw. When I calculate the mass
held and the stiffness of the ball screw by hand, I get the ~90 Hz - so the
assumption was probably correct.
So I started to debug my model:
If I set the ball screw stiffness to 0, I get a rigid body mode at 0 Hz - as
I would expect.
If I set the BS stiffness lower (using a hand calculation, I should get
18Hz, for example), I get a result at 17.5Hz and a "rigid" motion - OK, as
expected.
When I set BS stiffness higher, if axial motion mode is higher than other
modes, this mode is missing.... The first modes are at ~40-60Hz and then I
get modes at ~115 Hz.
The 90Hz mode is never there and can't be noticed as clearly as when the
stiffness is set for results below 40Hz.
Do you guys have any ideas? What am I missing?
Thank you in advance for any tips!
Best Regards,
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
Mail: mailto:martin.mazurowski@drehmoment.de
martin.mazurowski@drehmoment.de
Web: http://www.drehmoment.de/ www.drehmoment.de
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Dear all,
I have a problem here, I think I am missing something and I can't understand
what.
I made a modal analysis of a structure and then it was tested - the
correlation between test and FEA was ok.
Nevertheless, a mode was "not found".
The structure is supported on guide carriages and is held in axial direction
by a ball screw. The stiffness of these parts is represented with a
bushing-like element.
I suspected that the missing mode (at 90 Hz) is some kind of rigid body
motion due to the stiffness of the ball screw. When I calculate the mass
held and the stiffness of the ball screw by hand, I get the ~90 Hz - so the
assumption was probably correct.
So I started to debug my model:
If I set the ball screw stiffness to 0, I get a rigid body mode at 0 Hz - as
I would expect.
If I set the BS stiffness lower (using a hand calculation, I should get
18Hz, for example), I get a result at 17.5Hz and a "rigid" motion - OK, as
expected.
When I set BS stiffness higher, if axial motion mode is higher than other
modes, this mode is missing.... The first modes are at ~40-60Hz and then I
get modes at ~115 Hz.
The 90Hz mode is never there and can't be noticed as clearly as when the
stiffness is set for results below 40Hz.
Do you guys have any ideas? What am I missing?
Thank you in advance for any tips!
Best Regards,
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
Mail: <mailto:martin.mazurowski@drehmoment.de>
martin.mazurowski@drehmoment.de
Web: <http://www.drehmoment.de/> www.drehmoment.de
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
TR
Testi Riccardo
Thu, Mar 30, 2023 6:55 AM
Dear Mr. Mazurowski,
is the mass of the things you simulated as purely elastic negligible when compared to the mass of the rest of the structure?
Best regards
Riccardo Testi
Development and Strategies
2 Wheeler Engines Technical Centre
Piaggio & C. S.p.A
Viale Rinaldo Piaggio, 25
56025 Pontedera (Pisa) - ITALY
Phone: +39 0587 272850
Fax: +39 0587 272010
Mobile: +39 339 7241918
E-mail: riccardo.testi@piaggio.com
-----Original Message-----
From: martin.mazurowski@drehmoment.de martin.mazurowski@drehmoment.de
Sent: giovedì 30 marzo 2023 08:28
To: xansys-temp@list.xansys.org
Subject: [Xansys] [Struct][Modal] Missing eigenmode.
CAUTION:This email originated from outside the Piaggio Group. Do not click links or open attachments unless you recognize the sender and know the content is safe.
Dear all,
I have a problem here, I think I am missing something and I can't understand what.
I made a modal analysis of a structure and then it was tested - the correlation between test and FEA was ok.
Nevertheless, a mode was "not found".
The structure is supported on guide carriages and is held in axial direction by a ball screw. The stiffness of these parts is represented with a bushing-like element.
I suspected that the missing mode (at 90 Hz) is some kind of rigid body motion due to the stiffness of the ball screw. When I calculate the mass held and the stiffness of the ball screw by hand, I get the ~90 Hz - so the assumption was probably correct.
So I started to debug my model:
If I set the ball screw stiffness to 0, I get a rigid body mode at 0 Hz - as I would expect.
If I set the BS stiffness lower (using a hand calculation, I should get 18Hz, for example), I get a result at 17.5Hz and a "rigid" motion - OK, as expected.
When I set BS stiffness higher, if axial motion mode is higher than other modes, this mode is missing.... The first modes are at ~40-60Hz and then I get modes at ~115 Hz.
The 90Hz mode is never there and can't be noticed as clearly as when the stiffness is set for results below 40Hz.
Do you guys have any ideas? What am I missing?
Thank you in advance for any tips!
Best Regards,
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
Mail: mailto:martin.mazurowski@drehmoment.de
martin.mazurowski@drehmoment.de
Web: < https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de%2F&e=e5c82b6b&h=e5561f83&f=y&p=y > https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c82b6b&h=33f912d0&f=y&p=y
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Xansys mailing list -- xansys-temp@list.xansys.org To unsubscribe send an email to xansys-temp-leave@list.xansys.org If you are receiving too many emails from XANSYS please consider changing account settings to Digest mode which will send a single email per day.
Please send administrative requests such as deletion from XANSYS to xansys-mod@tynecomp.co.uk and not to the list
Dear Mr. Mazurowski,
is the mass of the things you simulated as purely elastic negligible when compared to the mass of the rest of the structure?
Best regards
Riccardo Testi
---
Development and Strategies
2 Wheeler Engines Technical Centre
Piaggio & C. S.p.A
Viale Rinaldo Piaggio, 25
56025 Pontedera (Pisa) - ITALY
Phone: +39 0587 272850
Fax: +39 0587 272010
Mobile: +39 339 7241918
E-mail: riccardo.testi@piaggio.com
-----Original Message-----
From: martin.mazurowski@drehmoment.de <martin.mazurowski@drehmoment.de>
Sent: giovedì 30 marzo 2023 08:28
To: xansys-temp@list.xansys.org
Subject: [Xansys] [Struct][Modal] Missing eigenmode.
CAUTION:This email originated from outside the Piaggio Group. Do not click links or open attachments unless you recognize the sender and know the content is safe.
Dear all,
I have a problem here, I think I am missing something and I can't understand what.
I made a modal analysis of a structure and then it was tested - the correlation between test and FEA was ok.
Nevertheless, a mode was "not found".
The structure is supported on guide carriages and is held in axial direction by a ball screw. The stiffness of these parts is represented with a bushing-like element.
I suspected that the missing mode (at 90 Hz) is some kind of rigid body motion due to the stiffness of the ball screw. When I calculate the mass held and the stiffness of the ball screw by hand, I get the ~90 Hz - so the assumption was probably correct.
So I started to debug my model:
If I set the ball screw stiffness to 0, I get a rigid body mode at 0 Hz - as I would expect.
If I set the BS stiffness lower (using a hand calculation, I should get 18Hz, for example), I get a result at 17.5Hz and a "rigid" motion - OK, as expected.
When I set BS stiffness higher, if axial motion mode is higher than other modes, this mode is missing.... The first modes are at ~40-60Hz and then I get modes at ~115 Hz.
The 90Hz mode is never there and can't be noticed as clearly as when the stiffness is set for results below 40Hz.
Do you guys have any ideas? What am I missing?
Thank you in advance for any tips!
Best Regards,
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
Mail: <mailto:martin.mazurowski@drehmoment.de>
martin.mazurowski@drehmoment.de
Web: < https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de%2F&e=e5c82b6b&h=e5561f83&f=y&p=y > https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c82b6b&h=33f912d0&f=y&p=y
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
_______________________________________________
Xansys mailing list -- xansys-temp@list.xansys.org To unsubscribe send an email to xansys-temp-leave@list.xansys.org If you are receiving too many emails from XANSYS please consider changing account settings to Digest mode which will send a single email per day.
Please send administrative requests such as deletion from XANSYS to xansys-mod@tynecomp.co.uk and not to the list
MM
martin.mazurowski@drehmoment.de
Thu, Mar 30, 2023 7:04 AM
Dear Mr. Testi,
you mean the Bushing/Spring elements used for the ball screw / guides?
Yes - those have 0 Mass.
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
MOBIL: +49 157 581 577 83
FAX: 08272 9952-99
Mail: martin.mazurowski@drehmoment.de
Web: www.drehmoment.de
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Handelsregister Augsburg HRB 21452
Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte Informationen enthalten. Wenn Sie nicht der richtige Adressat sind oder diese E-Mail irrtuemlich erhalten haben, informieren Sie bitte sofort den Absender und vernichten Sie diese E-Mail. Das unerlaubte Kopieren sowie die unbefugte Weitergabe dieser E-Mail ist nicht gestattet.
This e-mail may contain confidential and/or privileged information. If you are not the intended recipient or have received this e-mail in error, please notify the sender immediately and destroy this e-mail. Any unauthorised copying, disclosure or distribution of the material in this e-mail is strictly forbidden.
Please consider your environmental responsibility before printing this e-mail.
-----Ursprüngliche Nachricht-----
Von: Testi Riccardo riccardo.testi@piaggio.com
Gesendet: Donnerstag, 30. März 2023 08:56
An: XANSYS Mailing List Home xansys-temp@list.xansys.org
Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
Dear Mr. Mazurowski,
is the mass of the things you simulated as purely elastic negligible when compared to the mass of the rest of the structure?
Best regards
Riccardo Testi
Development and Strategies
2 Wheeler Engines Technical Centre
Piaggio & C. S.p.A
Viale Rinaldo Piaggio, 25
56025 Pontedera (Pisa) - ITALY
Phone: +39 0587 272850
Fax: +39 0587 272010
Mobile: +39 339 7241918
E-mail: riccardo.testi@piaggio.com
-----Original Message-----
From: martin.mazurowski@drehmoment.de martin.mazurowski@drehmoment.de
Sent: giovedì 30 marzo 2023 08:28
To: xansys-temp@list.xansys.org
Subject: [Xansys] [Struct][Modal] Missing eigenmode.
CAUTION:This email originated from outside the Piaggio Group. Do not click links or open attachments unless you recognize the sender and know the content is safe.
Dear all,
I have a problem here, I think I am missing something and I can't understand what.
I made a modal analysis of a structure and then it was tested - the correlation between test and FEA was ok.
Nevertheless, a mode was "not found".
The structure is supported on guide carriages and is held in axial direction by a ball screw. The stiffness of these parts is represented with a bushing-like element.
I suspected that the missing mode (at 90 Hz) is some kind of rigid body motion due to the stiffness of the ball screw. When I calculate the mass held and the stiffness of the ball screw by hand, I get the ~90 Hz - so the assumption was probably correct.
So I started to debug my model:
If I set the ball screw stiffness to 0, I get a rigid body mode at 0 Hz - as I would expect.
If I set the BS stiffness lower (using a hand calculation, I should get 18Hz, for example), I get a result at 17.5Hz and a "rigid" motion - OK, as expected.
When I set BS stiffness higher, if axial motion mode is higher than other modes, this mode is missing.... The first modes are at ~40-60Hz and then I get modes at ~115 Hz.
The 90Hz mode is never there and can't be noticed as clearly as when the stiffness is set for results below 40Hz.
Do you guys have any ideas? What am I missing?
Thank you in advance for any tips!
Best Regards,
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
Mail: mailto:martin.mazurowski@drehmoment.de
martin.mazurowski@drehmoment.de
Web: < https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de%2F&e=e5c82b6b&h=e5561f83&f=y&p=y > https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c82b6b&h=33f912d0&f=y&p=y
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Xansys mailing list -- xansys-temp@list.xansys.org To unsubscribe send an email to xansys-temp-leave@list.xansys.org If you are receiving too many emails from XANSYS please consider changing account settings to Digest mode which will send a single email per day.
Please send administrative requests such as deletion from XANSYS to xansys-mod@tynecomp.co.uk and not to the list
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Please send administrative requests such as deletion from XANSYS to xansys-mod@tynecomp.co.uk and not to the list
Dear Mr. Testi,
you mean the Bushing/Spring elements used for the ball screw / guides?
Yes - those have 0 Mass.
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
MOBIL: +49 157 581 577 83
FAX: 08272 9952-99
Mail: martin.mazurowski@drehmoment.de
Web: www.drehmoment.de
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Handelsregister Augsburg HRB 21452
Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte Informationen enthalten. Wenn Sie nicht der richtige Adressat sind oder diese E-Mail irrtuemlich erhalten haben, informieren Sie bitte sofort den Absender und vernichten Sie diese E-Mail. Das unerlaubte Kopieren sowie die unbefugte Weitergabe dieser E-Mail ist nicht gestattet.
This e-mail may contain confidential and/or privileged information. If you are not the intended recipient or have received this e-mail in error, please notify the sender immediately and destroy this e-mail. Any unauthorised copying, disclosure or distribution of the material in this e-mail is strictly forbidden.
Please consider your environmental responsibility before printing this e-mail.
-----Ursprüngliche Nachricht-----
Von: Testi Riccardo <riccardo.testi@piaggio.com>
Gesendet: Donnerstag, 30. März 2023 08:56
An: XANSYS Mailing List Home <xansys-temp@list.xansys.org>
Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
Dear Mr. Mazurowski,
is the mass of the things you simulated as purely elastic negligible when compared to the mass of the rest of the structure?
Best regards
Riccardo Testi
---
Development and Strategies
2 Wheeler Engines Technical Centre
Piaggio & C. S.p.A
Viale Rinaldo Piaggio, 25
56025 Pontedera (Pisa) - ITALY
Phone: +39 0587 272850
Fax: +39 0587 272010
Mobile: +39 339 7241918
E-mail: riccardo.testi@piaggio.com
-----Original Message-----
From: martin.mazurowski@drehmoment.de <martin.mazurowski@drehmoment.de>
Sent: giovedì 30 marzo 2023 08:28
To: xansys-temp@list.xansys.org
Subject: [Xansys] [Struct][Modal] Missing eigenmode.
CAUTION:This email originated from outside the Piaggio Group. Do not click links or open attachments unless you recognize the sender and know the content is safe.
Dear all,
I have a problem here, I think I am missing something and I can't understand what.
I made a modal analysis of a structure and then it was tested - the correlation between test and FEA was ok.
Nevertheless, a mode was "not found".
The structure is supported on guide carriages and is held in axial direction by a ball screw. The stiffness of these parts is represented with a bushing-like element.
I suspected that the missing mode (at 90 Hz) is some kind of rigid body motion due to the stiffness of the ball screw. When I calculate the mass held and the stiffness of the ball screw by hand, I get the ~90 Hz - so the assumption was probably correct.
So I started to debug my model:
If I set the ball screw stiffness to 0, I get a rigid body mode at 0 Hz - as I would expect.
If I set the BS stiffness lower (using a hand calculation, I should get 18Hz, for example), I get a result at 17.5Hz and a "rigid" motion - OK, as expected.
When I set BS stiffness higher, if axial motion mode is higher than other modes, this mode is missing.... The first modes are at ~40-60Hz and then I get modes at ~115 Hz.
The 90Hz mode is never there and can't be noticed as clearly as when the stiffness is set for results below 40Hz.
Do you guys have any ideas? What am I missing?
Thank you in advance for any tips!
Best Regards,
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
Mail: <mailto:martin.mazurowski@drehmoment.de>
martin.mazurowski@drehmoment.de
Web: < https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de%2F&e=e5c82b6b&h=e5561f83&f=y&p=y > https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c82b6b&h=33f912d0&f=y&p=y
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
_______________________________________________
Xansys mailing list -- xansys-temp@list.xansys.org To unsubscribe send an email to xansys-temp-leave@list.xansys.org If you are receiving too many emails from XANSYS please consider changing account settings to Digest mode which will send a single email per day.
Please send administrative requests such as deletion from XANSYS to xansys-mod@tynecomp.co.uk and not to the list
_______________________________________________
Xansys mailing list -- xansys-temp@list.xansys.org To unsubscribe send an email to xansys-temp-leave@list.xansys.org If you are receiving too many emails from XANSYS please consider changing account settings to Digest mode which will send a single email per day.
Please send administrative requests such as deletion from XANSYS to xansys-mod@tynecomp.co.uk and not to the list
MG
Mohammad Gharaibeh
Thu, Mar 30, 2023 7:37 AM
Are you selecting your Element type correctly? What are the boundary
conditions? If rigid body motion is anticipated, therefore your model is
free of constraints, right? Did you think about fixing, i.e., restraining,
the bolt somewhere?
Good Luck!
---====
Mohammad A Gharaibeh, Ph.D.
Associate Professor
Department of Mechanical Engineering
The Hashemite University
P.O. Box 330127
Zarqa, 13133, Jordan
Tel: +962 - 5 - 390 3333 Ext. 4771
Fax: +962 - 5 - 382 6348
---====
On Thu, Mar 30, 2023 at 9:31 AM martin.mazurowski@drehmoment.de wrote:
Dear all,
I have a problem here, I think I am missing something and I can't
understand
what.
I made a modal analysis of a structure and then it was tested - the
correlation between test and FEA was ok.
Nevertheless, a mode was "not found".
The structure is supported on guide carriages and is held in axial
direction
by a ball screw. The stiffness of these parts is represented with a
bushing-like element.
I suspected that the missing mode (at 90 Hz) is some kind of rigid body
motion due to the stiffness of the ball screw. When I calculate the mass
held and the stiffness of the ball screw by hand, I get the ~90 Hz - so the
assumption was probably correct.
So I started to debug my model:
If I set the ball screw stiffness to 0, I get a rigid body mode at 0 Hz -
as
I would expect.
If I set the BS stiffness lower (using a hand calculation, I should get
18Hz, for example), I get a result at 17.5Hz and a "rigid" motion - OK, as
expected.
When I set BS stiffness higher, if axial motion mode is higher than other
modes, this mode is missing.... The first modes are at ~40-60Hz and then I
get modes at ~115 Hz.
The 90Hz mode is never there and can't be noticed as clearly as when the
stiffness is set for results below 40Hz.
Do you guys have any ideas? What am I missing?
Thank you in advance for any tips!
Best Regards,
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
Mail: mailto:martin.mazurowski@drehmoment.de
martin.mazurowski@drehmoment.de
Web: http://www.drehmoment.de/ www.drehmoment.de
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Xansys mailing list -- xansys-temp@list.xansys.org
To unsubscribe send an email to xansys-temp-leave@list.xansys.org
If you are receiving too many emails from XANSYS please consider changing
account settings to Digest mode which will send a single email per day.
Please send administrative requests such as deletion from XANSYS to
xansys-mod@tynecomp.co.uk and not to the list
Are you selecting your Element type correctly? What are the boundary
conditions? If rigid body motion is anticipated, therefore your model is
free of constraints, right? Did you think about fixing, i.e., restraining,
the bolt somewhere?
Good Luck!
=====================================
Mohammad A Gharaibeh, Ph.D.
Associate Professor
Department of Mechanical Engineering
The Hashemite University
P.O. Box 330127
Zarqa, 13133, Jordan
Tel: +962 - 5 - 390 3333 Ext. 4771
Fax: +962 - 5 - 382 6348
=====================================
On Thu, Mar 30, 2023 at 9:31 AM <martin.mazurowski@drehmoment.de> wrote:
> Dear all,
>
>
>
> I have a problem here, I think I am missing something and I can't
> understand
> what.
>
>
>
> I made a modal analysis of a structure and then it was tested - the
> correlation between test and FEA was ok.
>
> Nevertheless, a mode was "not found".
>
>
>
> The structure is supported on guide carriages and is held in axial
> direction
> by a ball screw. The stiffness of these parts is represented with a
> bushing-like element.
>
> I suspected that the missing mode (at 90 Hz) is some kind of rigid body
> motion due to the stiffness of the ball screw. When I calculate the mass
> held and the stiffness of the ball screw by hand, I get the ~90 Hz - so the
> assumption was probably correct.
>
>
>
> So I started to debug my model:
>
> If I set the ball screw stiffness to 0, I get a rigid body mode at 0 Hz -
> as
> I would expect.
>
>
>
> If I set the BS stiffness lower (using a hand calculation, I should get
> 18Hz, for example), I get a result at 17.5Hz and a "rigid" motion - OK, as
> expected.
>
>
>
> When I set BS stiffness higher, if axial motion mode is higher than other
> modes, this mode is missing.... The first modes are at ~40-60Hz and then I
> get modes at ~115 Hz.
>
> The 90Hz mode is never there and can't be noticed as clearly as when the
> stiffness is set for results below 40Hz.
>
>
>
> Do you guys have any ideas? What am I missing?
>
> Thank you in advance for any tips!
>
>
>
> Best Regards,
>
>
>
> Mit freundlichen Grüßen,
>
>
>
> M. Eng. Martin Mazurowski
>
>
>
> Hauptstrasse 9
>
> D-86637 Wertingen
>
>
>
> FON: 08272 9952-29
>
> Mail: <mailto:martin.mazurowski@drehmoment.de>
> martin.mazurowski@drehmoment.de
>
> Web: <http://www.drehmoment.de/> www.drehmoment.de
>
>
>
> Geschäftsführer:
>
>
>
> Dipl.-Ing.(FH) Josef Hofer,
> B.Eng. Stefan Zobel,
>
> M.Eng. Martin Mazurowski
>
>
>
>
>
>
>
>
>
> _______________________________________________
> Xansys mailing list -- xansys-temp@list.xansys.org
> To unsubscribe send an email to xansys-temp-leave@list.xansys.org
> If you are receiving too many emails from XANSYS please consider changing
> account settings to Digest mode which will send a single email per day.
>
> Please send administrative requests such as deletion from XANSYS to
> xansys-mod@tynecomp.co.uk and not to the list
>
TR
Testi Riccardo
Thu, Mar 30, 2023 12:06 PM
Dear Mr. Mazurowski,
in fact, I was referring to the physical bodies. Can their mass be neglected while modelling and thus be substituted with purely elastic entities, such as springs or bushings?
Best regards
Riccardo Testi
-----Original Message-----
From: martin.mazurowski@drehmoment.de martin.mazurowski@drehmoment.de
Sent: giovedì 30 marzo 2023 09:04
To: 'XANSYS Mailing List Home' xansys-temp@list.xansys.org
Subject: [Xansys] Re: [Struct][Modal] Missing eigenmode.
CAUTION:This email originated from outside the Piaggio Group. Do not click links or open attachments unless you recognize the sender and know the content is safe.
Dear Mr. Testi,
you mean the Bushing/Spring elements used for the ball screw / guides?
Yes - those have 0 Mass.
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
MOBIL: +49 157 581 577 83
FAX: 08272 9952-99
Mail: martin.mazurowski@drehmoment.de
Web: https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c82b6b&h=33f912d0&f=y&p=y
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Handelsregister Augsburg HRB 21452
Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte Informationen enthalten. Wenn Sie nicht der richtige Adressat sind oder diese E-Mail irrtuemlich erhalten haben, informieren Sie bitte sofort den Absender und vernichten Sie diese E-Mail. Das unerlaubte Kopieren sowie die unbefugte Weitergabe dieser E-Mail ist nicht gestattet.
This e-mail may contain confidential and/or privileged information. If you are not the intended recipient or have received this e-mail in error, please notify the sender immediately and destroy this e-mail. Any unauthorised copying, disclosure or distribution of the material in this e-mail is strictly forbidden.
Please consider your environmental responsibility before printing this e-mail.
-----Ursprüngliche Nachricht-----
Von: Testi Riccardo riccardo.testi@piaggio.com
Gesendet: Donnerstag, 30. März 2023 08:56
An: XANSYS Mailing List Home xansys-temp@list.xansys.org
Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
Dear Mr. Mazurowski,
is the mass of the things you simulated as purely elastic negligible when compared to the mass of the rest of the structure?
Best regards
Riccardo Testi
Development and Strategies
2 Wheeler Engines Technical Centre
Piaggio & C. S.p.A
Viale Rinaldo Piaggio, 25
56025 Pontedera (Pisa) - ITALY
Phone: +39 0587 272850
Fax: +39 0587 272010
Mobile: +39 339 7241918
E-mail: riccardo.testi@piaggio.com
-----Original Message-----
From: martin.mazurowski@drehmoment.de martin.mazurowski@drehmoment.de
Sent: giovedì 30 marzo 2023 08:28
To: xansys-temp@list.xansys.org
Subject: [Xansys] [Struct][Modal] Missing eigenmode.
CAUTION:This email originated from outside the Piaggio Group. Do not click links or open attachments unless you recognize the sender and know the content is safe.
Dear all,
I have a problem here, I think I am missing something and I can't understand what.
I made a modal analysis of a structure and then it was tested - the correlation between test and FEA was ok.
Nevertheless, a mode was "not found".
The structure is supported on guide carriages and is held in axial direction by a ball screw. The stiffness of these parts is represented with a bushing-like element.
I suspected that the missing mode (at 90 Hz) is some kind of rigid body motion due to the stiffness of the ball screw. When I calculate the mass held and the stiffness of the ball screw by hand, I get the ~90 Hz - so the assumption was probably correct.
So I started to debug my model:
If I set the ball screw stiffness to 0, I get a rigid body mode at 0 Hz - as I would expect.
If I set the BS stiffness lower (using a hand calculation, I should get 18Hz, for example), I get a result at 17.5Hz and a "rigid" motion - OK, as expected.
When I set BS stiffness higher, if axial motion mode is higher than other modes, this mode is missing.... The first modes are at ~40-60Hz and then I get modes at ~115 Hz.
The 90Hz mode is never there and can't be noticed as clearly as when the stiffness is set for results below 40Hz.
Do you guys have any ideas? What am I missing?
Thank you in advance for any tips!
Best Regards,
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
Mail: mailto:martin.mazurowski@drehmoment.de
martin.mazurowski@drehmoment.de
Web: https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de%2F&e=e5c82b6b&h=e5561f83&f=y&p=y https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c82b6b&h=33f912d0&f=y&p=y
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Xansys mailing list -- xansys-temp@list.xansys.org To unsubscribe send an email to xansys-temp-leave@list.xansys.org If you are receiving too many emails from XANSYS please consider changing account settings to Digest mode which will send a single email per day.
Please send administrative requests such as deletion from XANSYS to xansys-mod@tynecomp.co.uk and not to the list
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Please send administrative requests such as deletion from XANSYS to xansys-mod@tynecomp.co.uk and not to the list _______________________________________________
Xansys mailing list -- xansys-temp@list.xansys.org To unsubscribe send an email to xansys-temp-leave@list.xansys.org If you are receiving too many emails from XANSYS please consider changing account settings to Digest mode which will send a single email per day.
Please send administrative requests such as deletion from XANSYS to xansys-mod@tynecomp.co.uk and not to the list
Dear Mr. Mazurowski,
in fact, I was referring to the physical bodies. Can their mass be neglected while modelling and thus be substituted with purely elastic entities, such as springs or bushings?
Best regards
Riccardo Testi
-----Original Message-----
From: martin.mazurowski@drehmoment.de <martin.mazurowski@drehmoment.de>
Sent: giovedì 30 marzo 2023 09:04
To: 'XANSYS Mailing List Home' <xansys-temp@list.xansys.org>
Subject: [Xansys] Re: [Struct][Modal] Missing eigenmode.
CAUTION:This email originated from outside the Piaggio Group. Do not click links or open attachments unless you recognize the sender and know the content is safe.
Dear Mr. Testi,
you mean the Bushing/Spring elements used for the ball screw / guides?
Yes - those have 0 Mass.
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
MOBIL: +49 157 581 577 83
FAX: 08272 9952-99
Mail: martin.mazurowski@drehmoment.de
Web: https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c82b6b&h=33f912d0&f=y&p=y
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Handelsregister Augsburg HRB 21452
Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte Informationen enthalten. Wenn Sie nicht der richtige Adressat sind oder diese E-Mail irrtuemlich erhalten haben, informieren Sie bitte sofort den Absender und vernichten Sie diese E-Mail. Das unerlaubte Kopieren sowie die unbefugte Weitergabe dieser E-Mail ist nicht gestattet.
This e-mail may contain confidential and/or privileged information. If you are not the intended recipient or have received this e-mail in error, please notify the sender immediately and destroy this e-mail. Any unauthorised copying, disclosure or distribution of the material in this e-mail is strictly forbidden.
Please consider your environmental responsibility before printing this e-mail.
-----Ursprüngliche Nachricht-----
Von: Testi Riccardo <riccardo.testi@piaggio.com>
Gesendet: Donnerstag, 30. März 2023 08:56
An: XANSYS Mailing List Home <xansys-temp@list.xansys.org>
Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
Dear Mr. Mazurowski,
is the mass of the things you simulated as purely elastic negligible when compared to the mass of the rest of the structure?
Best regards
Riccardo Testi
---
Development and Strategies
2 Wheeler Engines Technical Centre
Piaggio & C. S.p.A
Viale Rinaldo Piaggio, 25
56025 Pontedera (Pisa) - ITALY
Phone: +39 0587 272850
Fax: +39 0587 272010
Mobile: +39 339 7241918
E-mail: riccardo.testi@piaggio.com
-----Original Message-----
From: martin.mazurowski@drehmoment.de <martin.mazurowski@drehmoment.de>
Sent: giovedì 30 marzo 2023 08:28
To: xansys-temp@list.xansys.org
Subject: [Xansys] [Struct][Modal] Missing eigenmode.
CAUTION:This email originated from outside the Piaggio Group. Do not click links or open attachments unless you recognize the sender and know the content is safe.
Dear all,
I have a problem here, I think I am missing something and I can't understand what.
I made a modal analysis of a structure and then it was tested - the correlation between test and FEA was ok.
Nevertheless, a mode was "not found".
The structure is supported on guide carriages and is held in axial direction by a ball screw. The stiffness of these parts is represented with a bushing-like element.
I suspected that the missing mode (at 90 Hz) is some kind of rigid body motion due to the stiffness of the ball screw. When I calculate the mass held and the stiffness of the ball screw by hand, I get the ~90 Hz - so the assumption was probably correct.
So I started to debug my model:
If I set the ball screw stiffness to 0, I get a rigid body mode at 0 Hz - as I would expect.
If I set the BS stiffness lower (using a hand calculation, I should get 18Hz, for example), I get a result at 17.5Hz and a "rigid" motion - OK, as expected.
When I set BS stiffness higher, if axial motion mode is higher than other modes, this mode is missing.... The first modes are at ~40-60Hz and then I get modes at ~115 Hz.
The 90Hz mode is never there and can't be noticed as clearly as when the stiffness is set for results below 40Hz.
Do you guys have any ideas? What am I missing?
Thank you in advance for any tips!
Best Regards,
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
Mail: <mailto:martin.mazurowski@drehmoment.de>
martin.mazurowski@drehmoment.de
Web: <https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de%2F&e=e5c82b6b&h=e5561f83&f=y&p=y> https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c82b6b&h=33f912d0&f=y&p=y
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
_______________________________________________
Xansys mailing list -- xansys-temp@list.xansys.org To unsubscribe send an email to xansys-temp-leave@list.xansys.org If you are receiving too many emails from XANSYS please consider changing account settings to Digest mode which will send a single email per day.
Please send administrative requests such as deletion from XANSYS to xansys-mod@tynecomp.co.uk and not to the list
_______________________________________________
Xansys mailing list -- xansys-temp@list.xansys.org To unsubscribe send an email to xansys-temp-leave@list.xansys.org If you are receiving too many emails from XANSYS please consider changing account settings to Digest mode which will send a single email per day.
Please send administrative requests such as deletion from XANSYS to xansys-mod@tynecomp.co.uk and not to the list _______________________________________________
Xansys mailing list -- xansys-temp@list.xansys.org To unsubscribe send an email to xansys-temp-leave@list.xansys.org If you are receiving too many emails from XANSYS please consider changing account settings to Digest mode which will send a single email per day.
Please send administrative requests such as deletion from XANSYS to xansys-mod@tynecomp.co.uk and not to the list
MM
martin.mazurowski@drehmoment.de
Thu, Mar 30, 2023 12:30 PM
Hello Mr. Testi,
not in a practical way in my opinion.
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
MOBIL: +49 157 581 577 83
FAX: 08272 9952-99
Mail: martin.mazurowski@drehmoment.de
Web: www.drehmoment.de
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Handelsregister Augsburg HRB 21452
Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte Informationen enthalten. Wenn Sie nicht der richtige Adressat sind oder diese E-Mail irrtuemlich erhalten haben, informieren Sie bitte sofort den Absender und vernichten Sie diese E-Mail. Das unerlaubte Kopieren sowie die unbefugte Weitergabe dieser E-Mail ist nicht gestattet.
This e-mail may contain confidential and/or privileged information. If you are not the intended recipient or have received this e-mail in error, please notify the sender immediately and destroy this e-mail. Any unauthorised copying, disclosure or distribution of the material in this e-mail is strictly forbidden.
Please consider your environmental responsibility before printing this e-mail.
-----Ursprüngliche Nachricht-----
Von: Testi Riccardo riccardo.testi@piaggio.com
Gesendet: Donnerstag, 30. März 2023 14:06
An: XANSYS Mailing List Home xansys-temp@list.xansys.org
Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
Dear Mr. Mazurowski,
in fact, I was referring to the physical bodies. Can their mass be neglected while modelling and thus be substituted with purely elastic entities, such as springs or bushings?
Best regards
Riccardo Testi
-----Original Message-----
From: martin.mazurowski@drehmoment.de martin.mazurowski@drehmoment.de
Sent: giovedì 30 marzo 2023 09:04
To: 'XANSYS Mailing List Home' xansys-temp@list.xansys.org
Subject: [Xansys] Re: [Struct][Modal] Missing eigenmode.
CAUTION:This email originated from outside the Piaggio Group. Do not click links or open attachments unless you recognize the sender and know the content is safe.
Dear Mr. Testi,
you mean the Bushing/Spring elements used for the ball screw / guides?
Yes - those have 0 Mass.
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
MOBIL: +49 157 581 577 83
FAX: 08272 9952-99
Mail: martin.mazurowski@drehmoment.de
Web: https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c82b6b&h=33f912d0&f=y&p=y
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Handelsregister Augsburg HRB 21452
Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte Informationen enthalten. Wenn Sie nicht der richtige Adressat sind oder diese E-Mail irrtuemlich erhalten haben, informieren Sie bitte sofort den Absender und vernichten Sie diese E-Mail. Das unerlaubte Kopieren sowie die unbefugte Weitergabe dieser E-Mail ist nicht gestattet.
This e-mail may contain confidential and/or privileged information. If you are not the intended recipient or have received this e-mail in error, please notify the sender immediately and destroy this e-mail. Any unauthorised copying, disclosure or distribution of the material in this e-mail is strictly forbidden.
Please consider your environmental responsibility before printing this e-mail.
-----Ursprüngliche Nachricht-----
Von: Testi Riccardo riccardo.testi@piaggio.com
Gesendet: Donnerstag, 30. März 2023 08:56
An: XANSYS Mailing List Home xansys-temp@list.xansys.org
Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
Dear Mr. Mazurowski,
is the mass of the things you simulated as purely elastic negligible when compared to the mass of the rest of the structure?
Best regards
Riccardo Testi
Development and Strategies
2 Wheeler Engines Technical Centre
Piaggio & C. S.p.A
Viale Rinaldo Piaggio, 25
56025 Pontedera (Pisa) - ITALY
Phone: +39 0587 272850
Fax: +39 0587 272010
Mobile: +39 339 7241918
E-mail: riccardo.testi@piaggio.com
-----Original Message-----
From: martin.mazurowski@drehmoment.de martin.mazurowski@drehmoment.de
Sent: giovedì 30 marzo 2023 08:28
To: xansys-temp@list.xansys.org
Subject: [Xansys] [Struct][Modal] Missing eigenmode.
CAUTION:This email originated from outside the Piaggio Group. Do not click links or open attachments unless you recognize the sender and know the content is safe.
Dear all,
I have a problem here, I think I am missing something and I can't understand what.
I made a modal analysis of a structure and then it was tested - the correlation between test and FEA was ok.
Nevertheless, a mode was "not found".
The structure is supported on guide carriages and is held in axial direction by a ball screw. The stiffness of these parts is represented with a bushing-like element.
I suspected that the missing mode (at 90 Hz) is some kind of rigid body motion due to the stiffness of the ball screw. When I calculate the mass held and the stiffness of the ball screw by hand, I get the ~90 Hz - so the assumption was probably correct.
So I started to debug my model:
If I set the ball screw stiffness to 0, I get a rigid body mode at 0 Hz - as I would expect.
If I set the BS stiffness lower (using a hand calculation, I should get 18Hz, for example), I get a result at 17.5Hz and a "rigid" motion - OK, as expected.
When I set BS stiffness higher, if axial motion mode is higher than other modes, this mode is missing.... The first modes are at ~40-60Hz and then I get modes at ~115 Hz.
The 90Hz mode is never there and can't be noticed as clearly as when the stiffness is set for results below 40Hz.
Do you guys have any ideas? What am I missing?
Thank you in advance for any tips!
Best Regards,
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
Mail: mailto:martin.mazurowski@drehmoment.de
martin.mazurowski@drehmoment.de
Web: https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de%2F&e=e5c82b6b&h=e5561f83&f=y&p=y https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c82b6b&h=33f912d0&f=y&p=y
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Xansys mailing list -- xansys-temp@list.xansys.org To unsubscribe send an email to xansys-temp-leave@list.xansys.org If you are receiving too many emails from XANSYS please consider changing account settings to Digest mode which will send a single email per day.
Please send administrative requests such as deletion from XANSYS to xansys-mod@tynecomp.co.uk and not to the list
Xansys mailing list -- xansys-temp@list.xansys.org To unsubscribe send an email to xansys-temp-leave@list.xansys.org If you are receiving too many emails from XANSYS please consider changing account settings to Digest mode which will send a single email per day.
Please send administrative requests such as deletion from XANSYS to xansys-mod@tynecomp.co.uk and not to the list _______________________________________________
Xansys mailing list -- xansys-temp@list.xansys.org To unsubscribe send an email to xansys-temp-leave@list.xansys.org If you are receiving too many emails from XANSYS please consider changing account settings to Digest mode which will send a single email per day.
Please send administrative requests such as deletion from XANSYS to xansys-mod@tynecomp.co.uk and not to the list
Xansys mailing list -- xansys-temp@list.xansys.org To unsubscribe send an email to xansys-temp-leave@list.xansys.org If you are receiving too many emails from XANSYS please consider changing account settings to Digest mode which will send a single email per day.
Please send administrative requests such as deletion from XANSYS to xansys-mod@tynecomp.co.uk and not to the list
Hello Mr. Testi,
not in a practical way in my opinion.
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
MOBIL: +49 157 581 577 83
FAX: 08272 9952-99
Mail: martin.mazurowski@drehmoment.de
Web: www.drehmoment.de
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Handelsregister Augsburg HRB 21452
Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte Informationen enthalten. Wenn Sie nicht der richtige Adressat sind oder diese E-Mail irrtuemlich erhalten haben, informieren Sie bitte sofort den Absender und vernichten Sie diese E-Mail. Das unerlaubte Kopieren sowie die unbefugte Weitergabe dieser E-Mail ist nicht gestattet.
This e-mail may contain confidential and/or privileged information. If you are not the intended recipient or have received this e-mail in error, please notify the sender immediately and destroy this e-mail. Any unauthorised copying, disclosure or distribution of the material in this e-mail is strictly forbidden.
Please consider your environmental responsibility before printing this e-mail.
-----Ursprüngliche Nachricht-----
Von: Testi Riccardo <riccardo.testi@piaggio.com>
Gesendet: Donnerstag, 30. März 2023 14:06
An: XANSYS Mailing List Home <xansys-temp@list.xansys.org>
Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
Dear Mr. Mazurowski,
in fact, I was referring to the physical bodies. Can their mass be neglected while modelling and thus be substituted with purely elastic entities, such as springs or bushings?
Best regards
Riccardo Testi
-----Original Message-----
From: martin.mazurowski@drehmoment.de <martin.mazurowski@drehmoment.de>
Sent: giovedì 30 marzo 2023 09:04
To: 'XANSYS Mailing List Home' <xansys-temp@list.xansys.org>
Subject: [Xansys] Re: [Struct][Modal] Missing eigenmode.
CAUTION:This email originated from outside the Piaggio Group. Do not click links or open attachments unless you recognize the sender and know the content is safe.
Dear Mr. Testi,
you mean the Bushing/Spring elements used for the ball screw / guides?
Yes - those have 0 Mass.
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
MOBIL: +49 157 581 577 83
FAX: 08272 9952-99
Mail: martin.mazurowski@drehmoment.de
Web: https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c82b6b&h=33f912d0&f=y&p=y
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Handelsregister Augsburg HRB 21452
Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte Informationen enthalten. Wenn Sie nicht der richtige Adressat sind oder diese E-Mail irrtuemlich erhalten haben, informieren Sie bitte sofort den Absender und vernichten Sie diese E-Mail. Das unerlaubte Kopieren sowie die unbefugte Weitergabe dieser E-Mail ist nicht gestattet.
This e-mail may contain confidential and/or privileged information. If you are not the intended recipient or have received this e-mail in error, please notify the sender immediately and destroy this e-mail. Any unauthorised copying, disclosure or distribution of the material in this e-mail is strictly forbidden.
Please consider your environmental responsibility before printing this e-mail.
-----Ursprüngliche Nachricht-----
Von: Testi Riccardo <riccardo.testi@piaggio.com>
Gesendet: Donnerstag, 30. März 2023 08:56
An: XANSYS Mailing List Home <xansys-temp@list.xansys.org>
Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
Dear Mr. Mazurowski,
is the mass of the things you simulated as purely elastic negligible when compared to the mass of the rest of the structure?
Best regards
Riccardo Testi
---
Development and Strategies
2 Wheeler Engines Technical Centre
Piaggio & C. S.p.A
Viale Rinaldo Piaggio, 25
56025 Pontedera (Pisa) - ITALY
Phone: +39 0587 272850
Fax: +39 0587 272010
Mobile: +39 339 7241918
E-mail: riccardo.testi@piaggio.com
-----Original Message-----
From: martin.mazurowski@drehmoment.de <martin.mazurowski@drehmoment.de>
Sent: giovedì 30 marzo 2023 08:28
To: xansys-temp@list.xansys.org
Subject: [Xansys] [Struct][Modal] Missing eigenmode.
CAUTION:This email originated from outside the Piaggio Group. Do not click links or open attachments unless you recognize the sender and know the content is safe.
Dear all,
I have a problem here, I think I am missing something and I can't understand what.
I made a modal analysis of a structure and then it was tested - the correlation between test and FEA was ok.
Nevertheless, a mode was "not found".
The structure is supported on guide carriages and is held in axial direction by a ball screw. The stiffness of these parts is represented with a bushing-like element.
I suspected that the missing mode (at 90 Hz) is some kind of rigid body motion due to the stiffness of the ball screw. When I calculate the mass held and the stiffness of the ball screw by hand, I get the ~90 Hz - so the assumption was probably correct.
So I started to debug my model:
If I set the ball screw stiffness to 0, I get a rigid body mode at 0 Hz - as I would expect.
If I set the BS stiffness lower (using a hand calculation, I should get 18Hz, for example), I get a result at 17.5Hz and a "rigid" motion - OK, as expected.
When I set BS stiffness higher, if axial motion mode is higher than other modes, this mode is missing.... The first modes are at ~40-60Hz and then I get modes at ~115 Hz.
The 90Hz mode is never there and can't be noticed as clearly as when the stiffness is set for results below 40Hz.
Do you guys have any ideas? What am I missing?
Thank you in advance for any tips!
Best Regards,
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
Mail: <mailto:martin.mazurowski@drehmoment.de>
martin.mazurowski@drehmoment.de
Web: <https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de%2F&e=e5c82b6b&h=e5561f83&f=y&p=y> https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c82b6b&h=33f912d0&f=y&p=y
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
_______________________________________________
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SK
Sze Kwan Cheah
Thu, Mar 30, 2023 2:33 PM
Mr. Mazurowski,
I suspect the reason is because there is a coupling between the stiffness
from the ball screw (BS) and the modes in the undescribed structure similar
to a tuned-mass damper.
To test this hypothesis, in your original model, if you set your structure
to have an artificially large modulus of elasticity (e.g. 1000x), the 90Hz
pseudo-rigid-body mode would appear as in your hand calculation.
If the above is true, then it points to the hand calculation is inadequate
in replicating the experiment. Counter-intuitively, try increasing the
stiffness of the BS even higher than you have so far to hunt for the 90Hz
mode.
Good luck,
Sze Kwan (Jason) Cheah
Graduate Student
University of Minnesota - Twin Cities
On Thu, Mar 30, 2023 at 7:32 AM martin.mazurowski@drehmoment.de wrote:
Hello Mr. Testi,
not in a practical way in my opinion.
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
MOBIL: +49 157 581 577 83
FAX: 08272 9952-99
Mail: martin.mazurowski@drehmoment.de
Web: www.drehmoment.de
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Handelsregister Augsburg HRB 21452
Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte
Informationen enthalten. Wenn Sie nicht der richtige Adressat sind oder
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Absender und vernichten Sie diese E-Mail. Das unerlaubte Kopieren sowie die
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-----Ursprüngliche Nachricht-----
Von: Testi Riccardo riccardo.testi@piaggio.com
Gesendet: Donnerstag, 30. März 2023 14:06
An: XANSYS Mailing List Home xansys-temp@list.xansys.org
Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
Dear Mr. Mazurowski,
in fact, I was referring to the physical bodies. Can their mass be
neglected while modelling and thus be substituted with purely elastic
entities, such as springs or bushings?
Best regards
Riccardo Testi
-----Original Message-----
From: martin.mazurowski@drehmoment.de martin.mazurowski@drehmoment.de
Sent: giovedì 30 marzo 2023 09:04
To: 'XANSYS Mailing List Home' xansys-temp@list.xansys.org
Subject: [Xansys] Re: [Struct][Modal] Missing eigenmode.
CAUTION:This email originated from outside the Piaggio Group. Do not click
links or open attachments unless you recognize the sender and know the
content is safe.
Dear Mr. Testi,
you mean the Bushing/Spring elements used for the ball screw / guides?
Yes - those have 0 Mass.
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
MOBIL: +49 157 581 577 83
FAX: 08272 9952-99
Mail: martin.mazurowski@drehmoment.de
Web:
https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c82b6b&h=33f912d0&f=y&p=y
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Handelsregister Augsburg HRB 21452
Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte
Informationen enthalten. Wenn Sie nicht der richtige Adressat sind oder
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-----Ursprüngliche Nachricht-----
Von: Testi Riccardo riccardo.testi@piaggio.com
Gesendet: Donnerstag, 30. März 2023 08:56
An: XANSYS Mailing List Home xansys-temp@list.xansys.org
Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
Dear Mr. Mazurowski,
is the mass of the things you simulated as purely elastic negligible when
compared to the mass of the rest of the structure?
Best regards
Riccardo Testi
Development and Strategies
2 Wheeler Engines Technical Centre
Piaggio & C. S.p.A
Viale Rinaldo Piaggio, 25
56025 Pontedera (Pisa) - ITALY
Phone: +39 0587 272850
Fax: +39 0587 272010
Mobile: +39 339 7241918
E-mail: riccardo.testi@piaggio.com
-----Original Message-----
From: martin.mazurowski@drehmoment.de martin.mazurowski@drehmoment.de
Sent: giovedì 30 marzo 2023 08:28
To: xansys-temp@list.xansys.org
Subject: [Xansys] [Struct][Modal] Missing eigenmode.
CAUTION:This email originated from outside the Piaggio Group. Do not click
links or open attachments unless you recognize the sender and know the
content is safe.
Dear all,
I have a problem here, I think I am missing something and I can't
understand what.
I made a modal analysis of a structure and then it was tested - the
correlation between test and FEA was ok.
Nevertheless, a mode was "not found".
The structure is supported on guide carriages and is held in axial
direction by a ball screw. The stiffness of these parts is represented with
a bushing-like element.
I suspected that the missing mode (at 90 Hz) is some kind of rigid body
motion due to the stiffness of the ball screw. When I calculate the mass
held and the stiffness of the ball screw by hand, I get the ~90 Hz - so the
assumption was probably correct.
So I started to debug my model:
If I set the ball screw stiffness to 0, I get a rigid body mode at 0 Hz -
as I would expect.
If I set the BS stiffness lower (using a hand calculation, I should get
18Hz, for example), I get a result at 17.5Hz and a "rigid" motion - OK, as
expected.
When I set BS stiffness higher, if axial motion mode is higher than other
modes, this mode is missing.... The first modes are at ~40-60Hz and then I
get modes at ~115 Hz.
The 90Hz mode is never there and can't be noticed as clearly as when the
stiffness is set for results below 40Hz.
Do you guys have any ideas? What am I missing?
Thank you in advance for any tips!
Best Regards,
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
Mail: mailto:martin.mazurowski@drehmoment.de
martin.mazurowski@drehmoment.de
Web: <
https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de%2F&e=e5c82b6b&h=e5561f83&f=y&p=y>
https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c82b6b&h=33f912d0&f=y&p=y
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Xansys mailing list -- xansys-temp@list.xansys.org To unsubscribe send an
email to xansys-temp-leave@list.xansys.org If you are receiving too many
emails from XANSYS please consider changing account settings to Digest mode
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Mr. Mazurowski,
I suspect the reason is because there is a coupling between the stiffness
from the ball screw (BS) and the modes in the undescribed structure similar
to a tuned-mass damper.
To test this hypothesis, in your original model, if you set your structure
to have an artificially large modulus of elasticity (e.g. 1000x), the 90Hz
pseudo-rigid-body mode would appear as in your hand calculation.
If the above is true, then it points to the hand calculation is inadequate
in replicating the experiment. Counter-intuitively, try increasing the
stiffness of the BS even higher than you have so far to hunt for the 90Hz
mode.
Good luck,
Sze Kwan (Jason) Cheah
Graduate Student
University of Minnesota - Twin Cities
On Thu, Mar 30, 2023 at 7:32 AM <martin.mazurowski@drehmoment.de> wrote:
> Hello Mr. Testi,
>
> not in a practical way in my opinion.
>
> Mit freundlichen Grüßen,
>
> M. Eng. Martin Mazurowski
>
>
> Hauptstrasse 9
> D-86637 Wertingen
>
> FON: 08272 9952-29
> MOBIL: +49 157 581 577 83
> FAX: 08272 9952-99
> Mail: martin.mazurowski@drehmoment.de
> Web: www.drehmoment.de
>
> Geschäftsführer:
>
> Dipl.-Ing.(FH) Josef Hofer,
> B.Eng. Stefan Zobel,
> M.Eng. Martin Mazurowski
>
> Handelsregister Augsburg HRB 21452
>
> Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte
> Informationen enthalten. Wenn Sie nicht der richtige Adressat sind oder
> diese E-Mail irrtuemlich erhalten haben, informieren Sie bitte sofort den
> Absender und vernichten Sie diese E-Mail. Das unerlaubte Kopieren sowie die
> unbefugte Weitergabe dieser E-Mail ist nicht gestattet.
>
> This e-mail may contain confidential and/or privileged information. If you
> are not the intended recipient or have received this e-mail in error,
> please notify the sender immediately and destroy this e-mail. Any
> unauthorised copying, disclosure or distribution of the material in this
> e-mail is strictly forbidden.
> Please consider your environmental responsibility before printing this
> e-mail.
>
>
> -----Ursprüngliche Nachricht-----
> Von: Testi Riccardo <riccardo.testi@piaggio.com>
> Gesendet: Donnerstag, 30. März 2023 14:06
> An: XANSYS Mailing List Home <xansys-temp@list.xansys.org>
> Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
>
> Dear Mr. Mazurowski,
> in fact, I was referring to the physical bodies. Can their mass be
> neglected while modelling and thus be substituted with purely elastic
> entities, such as springs or bushings?
>
> Best regards
> Riccardo Testi
>
> -----Original Message-----
> From: martin.mazurowski@drehmoment.de <martin.mazurowski@drehmoment.de>
> Sent: giovedì 30 marzo 2023 09:04
> To: 'XANSYS Mailing List Home' <xansys-temp@list.xansys.org>
> Subject: [Xansys] Re: [Struct][Modal] Missing eigenmode.
>
> CAUTION:This email originated from outside the Piaggio Group. Do not click
> links or open attachments unless you recognize the sender and know the
> content is safe.
>
>
> Dear Mr. Testi,
>
> you mean the Bushing/Spring elements used for the ball screw / guides?
> Yes - those have 0 Mass.
>
> Mit freundlichen Grüßen,
>
> M. Eng. Martin Mazurowski
>
>
> Hauptstrasse 9
> D-86637 Wertingen
>
> FON: 08272 9952-29
> MOBIL: +49 157 581 577 83
> FAX: 08272 9952-99
> Mail: martin.mazurowski@drehmoment.de
> Web:
> https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c82b6b&h=33f912d0&f=y&p=y
>
> Geschäftsführer:
>
> Dipl.-Ing.(FH) Josef Hofer,
> B.Eng. Stefan Zobel,
> M.Eng. Martin Mazurowski
>
> Handelsregister Augsburg HRB 21452
>
> Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte
> Informationen enthalten. Wenn Sie nicht der richtige Adressat sind oder
> diese E-Mail irrtuemlich erhalten haben, informieren Sie bitte sofort den
> Absender und vernichten Sie diese E-Mail. Das unerlaubte Kopieren sowie die
> unbefugte Weitergabe dieser E-Mail ist nicht gestattet.
>
> This e-mail may contain confidential and/or privileged information. If you
> are not the intended recipient or have received this e-mail in error,
> please notify the sender immediately and destroy this e-mail. Any
> unauthorised copying, disclosure or distribution of the material in this
> e-mail is strictly forbidden.
> Please consider your environmental responsibility before printing this
> e-mail.
>
>
> -----Ursprüngliche Nachricht-----
> Von: Testi Riccardo <riccardo.testi@piaggio.com>
> Gesendet: Donnerstag, 30. März 2023 08:56
> An: XANSYS Mailing List Home <xansys-temp@list.xansys.org>
> Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
>
> Dear Mr. Mazurowski,
> is the mass of the things you simulated as purely elastic negligible when
> compared to the mass of the rest of the structure?
>
> Best regards
> Riccardo Testi
> ---
> Development and Strategies
> 2 Wheeler Engines Technical Centre
> Piaggio & C. S.p.A
> Viale Rinaldo Piaggio, 25
> 56025 Pontedera (Pisa) - ITALY
> Phone: +39 0587 272850
> Fax: +39 0587 272010
> Mobile: +39 339 7241918
> E-mail: riccardo.testi@piaggio.com
>
>
>
> -----Original Message-----
> From: martin.mazurowski@drehmoment.de <martin.mazurowski@drehmoment.de>
> Sent: giovedì 30 marzo 2023 08:28
> To: xansys-temp@list.xansys.org
> Subject: [Xansys] [Struct][Modal] Missing eigenmode.
>
> CAUTION:This email originated from outside the Piaggio Group. Do not click
> links or open attachments unless you recognize the sender and know the
> content is safe.
>
>
> Dear all,
>
>
>
> I have a problem here, I think I am missing something and I can't
> understand what.
>
>
>
> I made a modal analysis of a structure and then it was tested - the
> correlation between test and FEA was ok.
>
> Nevertheless, a mode was "not found".
>
>
>
> The structure is supported on guide carriages and is held in axial
> direction by a ball screw. The stiffness of these parts is represented with
> a bushing-like element.
>
> I suspected that the missing mode (at 90 Hz) is some kind of rigid body
> motion due to the stiffness of the ball screw. When I calculate the mass
> held and the stiffness of the ball screw by hand, I get the ~90 Hz - so the
> assumption was probably correct.
>
>
>
> So I started to debug my model:
>
> If I set the ball screw stiffness to 0, I get a rigid body mode at 0 Hz -
> as I would expect.
>
>
>
> If I set the BS stiffness lower (using a hand calculation, I should get
> 18Hz, for example), I get a result at 17.5Hz and a "rigid" motion - OK, as
> expected.
>
>
>
> When I set BS stiffness higher, if axial motion mode is higher than other
> modes, this mode is missing.... The first modes are at ~40-60Hz and then I
> get modes at ~115 Hz.
>
> The 90Hz mode is never there and can't be noticed as clearly as when the
> stiffness is set for results below 40Hz.
>
>
>
> Do you guys have any ideas? What am I missing?
>
> Thank you in advance for any tips!
>
>
>
> Best Regards,
>
>
>
> Mit freundlichen Grüßen,
>
>
>
> M. Eng. Martin Mazurowski
>
>
>
> Hauptstrasse 9
>
> D-86637 Wertingen
>
>
>
> FON: 08272 9952-29
>
> Mail: <mailto:martin.mazurowski@drehmoment.de>
> martin.mazurowski@drehmoment.de
>
> Web: <
> https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de%2F&e=e5c82b6b&h=e5561f83&f=y&p=y>
>
> https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c82b6b&h=33f912d0&f=y&p=y
>
>
>
> Geschäftsführer:
>
>
>
> Dipl.-Ing.(FH) Josef Hofer,
> B.Eng. Stefan Zobel,
>
> M.Eng. Martin Mazurowski
>
>
>
>
>
>
>
>
>
> _______________________________________________
> Xansys mailing list -- xansys-temp@list.xansys.org To unsubscribe send an
> email to xansys-temp-leave@list.xansys.org If you are receiving too many
> emails from XANSYS please consider changing account settings to Digest mode
> which will send a single email per day.
>
> Please send administrative requests such as deletion from XANSYS to
> xansys-mod@tynecomp.co.uk and not to the list
>
>
> _______________________________________________
> Xansys mailing list -- xansys-temp@list.xansys.org To unsubscribe send an
> email to xansys-temp-leave@list.xansys.org If you are receiving too many
> emails from XANSYS please consider changing account settings to Digest mode
> which will send a single email per day.
>
> Please send administrative requests such as deletion from XANSYS to
> xansys-mod@tynecomp.co.uk and not to the list
> _______________________________________________
> Xansys mailing list -- xansys-temp@list.xansys.org To unsubscribe send an
> email to xansys-temp-leave@list.xansys.org If you are receiving too many
> emails from XANSYS please consider changing account settings to Digest mode
> which will send a single email per day.
>
> Please send administrative requests such as deletion from XANSYS to
> xansys-mod@tynecomp.co.uk and not to the list
>
>
> _______________________________________________
> Xansys mailing list -- xansys-temp@list.xansys.org To unsubscribe send an
> email to xansys-temp-leave@list.xansys.org If you are receiving too many
> emails from XANSYS please consider changing account settings to Digest mode
> which will send a single email per day.
>
> Please send administrative requests such as deletion from XANSYS to
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> _______________________________________________
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> If you are receiving too many emails from XANSYS please consider changing
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> Please send administrative requests such as deletion from XANSYS to
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MM
martin.mazurowski@drehmoment.de
Thu, Mar 30, 2023 3:12 PM
Hi Jason,
thanks for your Tip, increasing the E Module of the structure results with rigid body movement at ~90Hz as I would expect.
I Will try your second tip with increasing the BS stiffnes.
Can you recommend any literature / articles /web sites where I could go deeper into this topic?
Because to be fair I'm a little bit lost.
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
MOBIL: +49 157 581 577 83
FAX: 08272 9952-99
Mail: martin.mazurowski@drehmoment.de
Web: www.drehmoment.de
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Handelsregister Augsburg HRB 21452
Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte Informationen enthalten. Wenn Sie nicht der richtige Adressat sind oder diese E-Mail irrtuemlich erhalten haben, informieren Sie bitte sofort den Absender und vernichten Sie diese E-Mail. Das unerlaubte Kopieren sowie die unbefugte Weitergabe dieser E-Mail ist nicht gestattet.
This e-mail may contain confidential and/or privileged information. If you are not the intended recipient or have received this e-mail in error, please notify the sender immediately and destroy this e-mail. Any unauthorised copying, disclosure or distribution of the material in this e-mail is strictly forbidden.
Please consider your environmental responsibility before printing this e-mail.
-----Ursprüngliche Nachricht-----
Von: Sze Kwan Cheah via Xansys xansys-temp@list.xansys.org
Gesendet: Donnerstag, 30. März 2023 16:33
An: XANSYS Mailing List Home xansys-temp@list.xansys.org
Cc: Sze Kwan Cheah cheah013@umn.edu
Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
Mr. Mazurowski,
I suspect the reason is because there is a coupling between the stiffness from the ball screw (BS) and the modes in the undescribed structure similar to a tuned-mass damper.
To test this hypothesis, in your original model, if you set your structure to have an artificially large modulus of elasticity (e.g. 1000x), the 90Hz pseudo-rigid-body mode would appear as in your hand calculation.
If the above is true, then it points to the hand calculation is inadequate in replicating the experiment. Counter-intuitively, try increasing the stiffness of the BS even higher than you have so far to hunt for the 90Hz mode.
Good luck,
Sze Kwan (Jason) Cheah
Graduate Student
University of Minnesota - Twin Cities
On Thu, Mar 30, 2023 at 7:32 AM martin.mazurowski@drehmoment.de wrote:
Hello Mr. Testi,
not in a practical way in my opinion.
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
MOBIL: +49 157 581 577 83
FAX: 08272 9952-99
Mail: martin.mazurowski@drehmoment.de
Web: www.drehmoment.de
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Handelsregister Augsburg HRB 21452
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-----Ursprüngliche Nachricht-----
Von: Testi Riccardo riccardo.testi@piaggio.com
Gesendet: Donnerstag, 30. März 2023 14:06
An: XANSYS Mailing List Home xansys-temp@list.xansys.org
Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
Dear Mr. Mazurowski,
in fact, I was referring to the physical bodies. Can their mass be
neglected while modelling and thus be substituted with purely elastic
entities, such as springs or bushings?
Best regards
Riccardo Testi
-----Original Message-----
From: martin.mazurowski@drehmoment.de
martin.mazurowski@drehmoment.de
Sent: giovedì 30 marzo 2023 09:04
To: 'XANSYS Mailing List Home' xansys-temp@list.xansys.org
Subject: [Xansys] Re: [Struct][Modal] Missing eigenmode.
CAUTION:This email originated from outside the Piaggio Group. Do not
click links or open attachments unless you recognize the sender and
know the content is safe.
Dear Mr. Testi,
you mean the Bushing/Spring elements used for the ball screw / guides?
Yes - those have 0 Mass.
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
MOBIL: +49 157 581 577 83
FAX: 08272 9952-99
Mail: martin.mazurowski@drehmoment.de
Web:
https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c82
b6b&h=33f912d0&f=y&p=y
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Handelsregister Augsburg HRB 21452
Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte
Informationen enthalten. Wenn Sie nicht der richtige Adressat sind
oder diese E-Mail irrtuemlich erhalten haben, informieren Sie bitte
sofort den Absender und vernichten Sie diese E-Mail. Das unerlaubte
Kopieren sowie die unbefugte Weitergabe dieser E-Mail ist nicht gestattet.
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Please consider your environmental responsibility before printing
this e-mail.
-----Ursprüngliche Nachricht-----
Von: Testi Riccardo riccardo.testi@piaggio.com
Gesendet: Donnerstag, 30. März 2023 08:56
An: XANSYS Mailing List Home xansys-temp@list.xansys.org
Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
Dear Mr. Mazurowski,
is the mass of the things you simulated as purely elastic negligible
when compared to the mass of the rest of the structure?
Best regards
Riccardo Testi
Development and Strategies
2 Wheeler Engines Technical Centre
Piaggio & C. S.p.A
Viale Rinaldo Piaggio, 25
56025 Pontedera (Pisa) - ITALY
Phone: +39 0587 272850
Fax: +39 0587 272010
Mobile: +39 339 7241918
E-mail: riccardo.testi@piaggio.com
-----Original Message-----
From: martin.mazurowski@drehmoment.de
martin.mazurowski@drehmoment.de
Sent: giovedì 30 marzo 2023 08:28
To: xansys-temp@list.xansys.org
Subject: [Xansys] [Struct][Modal] Missing eigenmode.
CAUTION:This email originated from outside the Piaggio Group. Do not
click links or open attachments unless you recognize the sender and
know the content is safe.
Dear all,
I have a problem here, I think I am missing something and I can't
understand what.
I made a modal analysis of a structure and then it was tested - the
correlation between test and FEA was ok.
Nevertheless, a mode was "not found".
The structure is supported on guide carriages and is held in axial
direction by a ball screw. The stiffness of these parts is represented
with a bushing-like element.
I suspected that the missing mode (at 90 Hz) is some kind of rigid
body motion due to the stiffness of the ball screw. When I calculate
the mass held and the stiffness of the ball screw by hand, I get the
~90 Hz - so the assumption was probably correct.
So I started to debug my model:
If I set the ball screw stiffness to 0, I get a rigid body mode at 0
Hz - as I would expect.
If I set the BS stiffness lower (using a hand calculation, I should
get 18Hz, for example), I get a result at 17.5Hz and a "rigid" motion
When I set BS stiffness higher, if axial motion mode is higher than
other modes, this mode is missing.... The first modes are at ~40-60Hz
and then I get modes at ~115 Hz.
The 90Hz mode is never there and can't be noticed as clearly as when
the stiffness is set for results below 40Hz.
Do you guys have any ideas? What am I missing?
Thank you in advance for any tips!
Best Regards,
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
Mail: mailto:martin.mazurowski@drehmoment.de
martin.mazurowski@drehmoment.de
Web: <
https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de%2F&e=e5
c82b6b&h=e5561f83&f=y&p=y>
https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c82
b6b&h=33f912d0&f=y&p=y
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
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Hi Jason,
thanks for your Tip, increasing the E Module of the structure results with rigid body movement at ~90Hz as I would expect.
I Will try your second tip with increasing the BS stiffnes.
Can you recommend any literature / articles /web sites where I could go deeper into this topic?
Because to be fair I'm a little bit lost.
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
MOBIL: +49 157 581 577 83
FAX: 08272 9952-99
Mail: martin.mazurowski@drehmoment.de
Web: www.drehmoment.de
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Handelsregister Augsburg HRB 21452
Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte Informationen enthalten. Wenn Sie nicht der richtige Adressat sind oder diese E-Mail irrtuemlich erhalten haben, informieren Sie bitte sofort den Absender und vernichten Sie diese E-Mail. Das unerlaubte Kopieren sowie die unbefugte Weitergabe dieser E-Mail ist nicht gestattet.
This e-mail may contain confidential and/or privileged information. If you are not the intended recipient or have received this e-mail in error, please notify the sender immediately and destroy this e-mail. Any unauthorised copying, disclosure or distribution of the material in this e-mail is strictly forbidden.
Please consider your environmental responsibility before printing this e-mail.
-----Ursprüngliche Nachricht-----
Von: Sze Kwan Cheah via Xansys <xansys-temp@list.xansys.org>
Gesendet: Donnerstag, 30. März 2023 16:33
An: XANSYS Mailing List Home <xansys-temp@list.xansys.org>
Cc: Sze Kwan Cheah <cheah013@umn.edu>
Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
Mr. Mazurowski,
I suspect the reason is because there is a coupling between the stiffness from the ball screw (BS) and the modes in the undescribed structure similar to a tuned-mass damper.
To test this hypothesis, in your original model, if you set your structure to have an artificially large modulus of elasticity (e.g. 1000x), the 90Hz pseudo-rigid-body mode would appear as in your hand calculation.
If the above is true, then it points to the hand calculation is inadequate in replicating the experiment. Counter-intuitively, try increasing the stiffness of the BS even higher than you have so far to hunt for the 90Hz mode.
Good luck,
Sze Kwan (Jason) Cheah
Graduate Student
University of Minnesota - Twin Cities
On Thu, Mar 30, 2023 at 7:32 AM <martin.mazurowski@drehmoment.de> wrote:
> Hello Mr. Testi,
>
> not in a practical way in my opinion.
>
> Mit freundlichen Grüßen,
>
> M. Eng. Martin Mazurowski
>
>
> Hauptstrasse 9
> D-86637 Wertingen
>
> FON: 08272 9952-29
> MOBIL: +49 157 581 577 83
> FAX: 08272 9952-99
> Mail: martin.mazurowski@drehmoment.de
> Web: www.drehmoment.de
>
> Geschäftsführer:
>
> Dipl.-Ing.(FH) Josef Hofer,
> B.Eng. Stefan Zobel,
> M.Eng. Martin Mazurowski
>
> Handelsregister Augsburg HRB 21452
>
> Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte
> Informationen enthalten. Wenn Sie nicht der richtige Adressat sind
> oder diese E-Mail irrtuemlich erhalten haben, informieren Sie bitte
> sofort den Absender und vernichten Sie diese E-Mail. Das unerlaubte
> Kopieren sowie die unbefugte Weitergabe dieser E-Mail ist nicht gestattet.
>
> This e-mail may contain confidential and/or privileged information. If
> you are not the intended recipient or have received this e-mail in
> error, please notify the sender immediately and destroy this e-mail.
> Any unauthorised copying, disclosure or distribution of the material
> in this e-mail is strictly forbidden.
> Please consider your environmental responsibility before printing
> this e-mail.
>
>
> -----Ursprüngliche Nachricht-----
> Von: Testi Riccardo <riccardo.testi@piaggio.com>
> Gesendet: Donnerstag, 30. März 2023 14:06
> An: XANSYS Mailing List Home <xansys-temp@list.xansys.org>
> Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
>
> Dear Mr. Mazurowski,
> in fact, I was referring to the physical bodies. Can their mass be
> neglected while modelling and thus be substituted with purely elastic
> entities, such as springs or bushings?
>
> Best regards
> Riccardo Testi
>
> -----Original Message-----
> From: martin.mazurowski@drehmoment.de
> <martin.mazurowski@drehmoment.de>
> Sent: giovedì 30 marzo 2023 09:04
> To: 'XANSYS Mailing List Home' <xansys-temp@list.xansys.org>
> Subject: [Xansys] Re: [Struct][Modal] Missing eigenmode.
>
> CAUTION:This email originated from outside the Piaggio Group. Do not
> click links or open attachments unless you recognize the sender and
> know the content is safe.
>
>
> Dear Mr. Testi,
>
> you mean the Bushing/Spring elements used for the ball screw / guides?
> Yes - those have 0 Mass.
>
> Mit freundlichen Grüßen,
>
> M. Eng. Martin Mazurowski
>
>
> Hauptstrasse 9
> D-86637 Wertingen
>
> FON: 08272 9952-29
> MOBIL: +49 157 581 577 83
> FAX: 08272 9952-99
> Mail: martin.mazurowski@drehmoment.de
> Web:
> https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c82
> b6b&h=33f912d0&f=y&p=y
>
> Geschäftsführer:
>
> Dipl.-Ing.(FH) Josef Hofer,
> B.Eng. Stefan Zobel,
> M.Eng. Martin Mazurowski
>
> Handelsregister Augsburg HRB 21452
>
> Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte
> Informationen enthalten. Wenn Sie nicht der richtige Adressat sind
> oder diese E-Mail irrtuemlich erhalten haben, informieren Sie bitte
> sofort den Absender und vernichten Sie diese E-Mail. Das unerlaubte
> Kopieren sowie die unbefugte Weitergabe dieser E-Mail ist nicht gestattet.
>
> This e-mail may contain confidential and/or privileged information. If
> you are not the intended recipient or have received this e-mail in
> error, please notify the sender immediately and destroy this e-mail.
> Any unauthorised copying, disclosure or distribution of the material
> in this e-mail is strictly forbidden.
> Please consider your environmental responsibility before printing
> this e-mail.
>
>
> -----Ursprüngliche Nachricht-----
> Von: Testi Riccardo <riccardo.testi@piaggio.com>
> Gesendet: Donnerstag, 30. März 2023 08:56
> An: XANSYS Mailing List Home <xansys-temp@list.xansys.org>
> Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
>
> Dear Mr. Mazurowski,
> is the mass of the things you simulated as purely elastic negligible
> when compared to the mass of the rest of the structure?
>
> Best regards
> Riccardo Testi
> ---
> Development and Strategies
> 2 Wheeler Engines Technical Centre
> Piaggio & C. S.p.A
> Viale Rinaldo Piaggio, 25
> 56025 Pontedera (Pisa) - ITALY
> Phone: +39 0587 272850
> Fax: +39 0587 272010
> Mobile: +39 339 7241918
> E-mail: riccardo.testi@piaggio.com
>
>
>
> -----Original Message-----
> From: martin.mazurowski@drehmoment.de
> <martin.mazurowski@drehmoment.de>
> Sent: giovedì 30 marzo 2023 08:28
> To: xansys-temp@list.xansys.org
> Subject: [Xansys] [Struct][Modal] Missing eigenmode.
>
> CAUTION:This email originated from outside the Piaggio Group. Do not
> click links or open attachments unless you recognize the sender and
> know the content is safe.
>
>
> Dear all,
>
>
>
> I have a problem here, I think I am missing something and I can't
> understand what.
>
>
>
> I made a modal analysis of a structure and then it was tested - the
> correlation between test and FEA was ok.
>
> Nevertheless, a mode was "not found".
>
>
>
> The structure is supported on guide carriages and is held in axial
> direction by a ball screw. The stiffness of these parts is represented
> with a bushing-like element.
>
> I suspected that the missing mode (at 90 Hz) is some kind of rigid
> body motion due to the stiffness of the ball screw. When I calculate
> the mass held and the stiffness of the ball screw by hand, I get the
> ~90 Hz - so the assumption was probably correct.
>
>
>
> So I started to debug my model:
>
> If I set the ball screw stiffness to 0, I get a rigid body mode at 0
> Hz - as I would expect.
>
>
>
> If I set the BS stiffness lower (using a hand calculation, I should
> get 18Hz, for example), I get a result at 17.5Hz and a "rigid" motion
> - OK, as expected.
>
>
>
> When I set BS stiffness higher, if axial motion mode is higher than
> other modes, this mode is missing.... The first modes are at ~40-60Hz
> and then I get modes at ~115 Hz.
>
> The 90Hz mode is never there and can't be noticed as clearly as when
> the stiffness is set for results below 40Hz.
>
>
>
> Do you guys have any ideas? What am I missing?
>
> Thank you in advance for any tips!
>
>
>
> Best Regards,
>
>
>
> Mit freundlichen Grüßen,
>
>
>
> M. Eng. Martin Mazurowski
>
>
>
> Hauptstrasse 9
>
> D-86637 Wertingen
>
>
>
> FON: 08272 9952-29
>
> Mail: <mailto:martin.mazurowski@drehmoment.de>
> martin.mazurowski@drehmoment.de
>
> Web: <
> https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de%2F&e=e5
> c82b6b&h=e5561f83&f=y&p=y>
>
> https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c82
> b6b&h=33f912d0&f=y&p=y
>
>
>
> Geschäftsführer:
>
>
>
> Dipl.-Ing.(FH) Josef Hofer,
> B.Eng. Stefan Zobel,
>
> M.Eng. Martin Mazurowski
>
>
>
>
>
>
>
>
>
> _______________________________________________
> Xansys mailing list -- xansys-temp@list.xansys.org To unsubscribe send
> an email to xansys-temp-leave@list.xansys.org If you are receiving too
> many emails from XANSYS please consider changing account settings to
> Digest mode which will send a single email per day.
>
> Please send administrative requests such as deletion from XANSYS to
> xansys-mod@tynecomp.co.uk and not to the list
>
>
> _______________________________________________
> Xansys mailing list -- xansys-temp@list.xansys.org To unsubscribe send
> an email to xansys-temp-leave@list.xansys.org If you are receiving too
> many emails from XANSYS please consider changing account settings to
> Digest mode which will send a single email per day.
>
> Please send administrative requests such as deletion from XANSYS to
> xansys-mod@tynecomp.co.uk and not to the list
> _______________________________________________
> Xansys mailing list -- xansys-temp@list.xansys.org To unsubscribe send
> an email to xansys-temp-leave@list.xansys.org If you are receiving too
> many emails from XANSYS please consider changing account settings to
> Digest mode which will send a single email per day.
>
> Please send administrative requests such as deletion from XANSYS to
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>
>
> _______________________________________________
> Xansys mailing list -- xansys-temp@list.xansys.org To unsubscribe send
> an email to xansys-temp-leave@list.xansys.org If you are receiving too
> many emails from XANSYS please consider changing account settings to
> Digest mode which will send a single email per day.
>
> Please send administrative requests such as deletion from XANSYS to
> xansys-mod@tynecomp.co.uk and not to the list
> _______________________________________________
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> an email to xansys-temp-leave@list.xansys.org If you are receiving too
> many emails from XANSYS please consider changing account settings to
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> Please send administrative requests such as deletion from XANSYS to
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_______________________________________________
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Please send administrative requests such as deletion from XANSYS to xansys-mod@tynecomp.co.uk and not to the list
SK
Sze Kwan Cheah
Thu, Mar 30, 2023 6:27 PM
Hi Martin,
My simple framework is one step above single-degree-of-freedom (SDOF), a 2
mass system. Please see for the following discussion:
https://www.acs.psu.edu/drussell/Demos/absorber/DynamicAbsorber.html
The animations are quite good. In the plot below, the dash-lines in the
main mass displacement show the SDOF response. With the additional dynamic
of the second mass, the solid lines show the two natural frequencies, one
above and below the SDOF. This might be analogous to your system where the
BS stiffness is the base spring and undescribed structure behaving like the
two mass or likely a more complicated version of it.
The pseudo-rigid body mode in this example dropped when the tuned mass was
added (solid to dash lines). That is why I suggested trying increasing the
BS stiffness to bring it up.
That said, the accuracy of the rest of the unsaid structure is equally
important as shown in the two mass example. Because dynamic boundary
conditions are highly uncertain, modal test with free-free boundary
condition is often done to correlate the structure before adding on the
actual boundary conditions experimentally and analytically. If your
structure is still instrumented, it's something to consider doing.
Best regards,
Jason
University of Minnesota
On Thu, Mar 30, 2023 at 10:13 AM martin.mazurowski@drehmoment.de wrote:
Hi Jason,
thanks for your Tip, increasing the E Module of the structure results with
rigid body movement at ~90Hz as I would expect.
I Will try your second tip with increasing the BS stiffnes.
Can you recommend any literature / articles /web sites where I could go
deeper into this topic?
Because to be fair I'm a little bit lost.
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
MOBIL: +49 157 581 577 83
FAX: 08272 9952-99
Mail: martin.mazurowski@drehmoment.de
Web: www.drehmoment.de
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Handelsregister Augsburg HRB 21452
Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte
Informationen enthalten. Wenn Sie nicht der richtige Adressat sind oder
diese E-Mail irrtuemlich erhalten haben, informieren Sie bitte sofort den
Absender und vernichten Sie diese E-Mail. Das unerlaubte Kopieren sowie die
unbefugte Weitergabe dieser E-Mail ist nicht gestattet.
This e-mail may contain confidential and/or privileged information. If you
are not the intended recipient or have received this e-mail in error,
please notify the sender immediately and destroy this e-mail. Any
unauthorised copying, disclosure or distribution of the material in this
e-mail is strictly forbidden.
Please consider your environmental responsibility before printing this
e-mail.
-----Ursprüngliche Nachricht-----
Von: Sze Kwan Cheah via Xansys xansys-temp@list.xansys.org
Gesendet: Donnerstag, 30. März 2023 16:33
An: XANSYS Mailing List Home xansys-temp@list.xansys.org
Cc: Sze Kwan Cheah cheah013@umn.edu
Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
Mr. Mazurowski,
I suspect the reason is because there is a coupling between the stiffness
from the ball screw (BS) and the modes in the undescribed structure similar
to a tuned-mass damper.
To test this hypothesis, in your original model, if you set your structure
to have an artificially large modulus of elasticity (e.g. 1000x), the 90Hz
pseudo-rigid-body mode would appear as in your hand calculation.
If the above is true, then it points to the hand calculation is inadequate
in replicating the experiment. Counter-intuitively, try increasing the
stiffness of the BS even higher than you have so far to hunt for the 90Hz
mode.
Good luck,
Sze Kwan (Jason) Cheah
Graduate Student
University of Minnesota - Twin Cities
On Thu, Mar 30, 2023 at 7:32 AM martin.mazurowski@drehmoment.de wrote:
Hello Mr. Testi,
not in a practical way in my opinion.
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
MOBIL: +49 157 581 577 83
FAX: 08272 9952-99
Mail: martin.mazurowski@drehmoment.de
Web: www.drehmoment.de
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Handelsregister Augsburg HRB 21452
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-----Ursprüngliche Nachricht-----
Von: Testi Riccardo riccardo.testi@piaggio.com
Gesendet: Donnerstag, 30. März 2023 14:06
An: XANSYS Mailing List Home xansys-temp@list.xansys.org
Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
Dear Mr. Mazurowski,
in fact, I was referring to the physical bodies. Can their mass be
neglected while modelling and thus be substituted with purely elastic
entities, such as springs or bushings?
Best regards
Riccardo Testi
-----Original Message-----
From: martin.mazurowski@drehmoment.de
martin.mazurowski@drehmoment.de
Sent: giovedì 30 marzo 2023 09:04
To: 'XANSYS Mailing List Home' xansys-temp@list.xansys.org
Subject: [Xansys] Re: [Struct][Modal] Missing eigenmode.
CAUTION:This email originated from outside the Piaggio Group. Do not
click links or open attachments unless you recognize the sender and
know the content is safe.
Dear Mr. Testi,
you mean the Bushing/Spring elements used for the ball screw / guides?
Yes - those have 0 Mass.
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
MOBIL: +49 157 581 577 83
FAX: 08272 9952-99
Mail: martin.mazurowski@drehmoment.de
Web:
https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c82
b6b&h=33f912d0&f=y&p=y
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Handelsregister Augsburg HRB 21452
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-----Ursprüngliche Nachricht-----
Von: Testi Riccardo riccardo.testi@piaggio.com
Gesendet: Donnerstag, 30. März 2023 08:56
An: XANSYS Mailing List Home xansys-temp@list.xansys.org
Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
Dear Mr. Mazurowski,
is the mass of the things you simulated as purely elastic negligible
when compared to the mass of the rest of the structure?
Best regards
Riccardo Testi
Development and Strategies
2 Wheeler Engines Technical Centre
Piaggio & C. S.p.A
Viale Rinaldo Piaggio, 25
56025 Pontedera (Pisa) - ITALY
Phone: +39 0587 272850
Fax: +39 0587 272010
Mobile: +39 339 7241918
E-mail: riccardo.testi@piaggio.com
-----Original Message-----
From: martin.mazurowski@drehmoment.de
martin.mazurowski@drehmoment.de
Sent: giovedì 30 marzo 2023 08:28
To: xansys-temp@list.xansys.org
Subject: [Xansys] [Struct][Modal] Missing eigenmode.
CAUTION:This email originated from outside the Piaggio Group. Do not
click links or open attachments unless you recognize the sender and
know the content is safe.
Dear all,
I have a problem here, I think I am missing something and I can't
understand what.
I made a modal analysis of a structure and then it was tested - the
correlation between test and FEA was ok.
Nevertheless, a mode was "not found".
The structure is supported on guide carriages and is held in axial
direction by a ball screw. The stiffness of these parts is represented
with a bushing-like element.
I suspected that the missing mode (at 90 Hz) is some kind of rigid
body motion due to the stiffness of the ball screw. When I calculate
the mass held and the stiffness of the ball screw by hand, I get the
~90 Hz - so the assumption was probably correct.
So I started to debug my model:
If I set the ball screw stiffness to 0, I get a rigid body mode at 0
Hz - as I would expect.
If I set the BS stiffness lower (using a hand calculation, I should
get 18Hz, for example), I get a result at 17.5Hz and a "rigid" motion
When I set BS stiffness higher, if axial motion mode is higher than
other modes, this mode is missing.... The first modes are at ~40-60Hz
and then I get modes at ~115 Hz.
The 90Hz mode is never there and can't be noticed as clearly as when
the stiffness is set for results below 40Hz.
Do you guys have any ideas? What am I missing?
Thank you in advance for any tips!
Best Regards,
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
Mail: mailto:martin.mazurowski@drehmoment.de
martin.mazurowski@drehmoment.de
Web: <
https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de%2F&e=e5
c82b6b&h=e5561f83&f=y&p=y>
https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c82
b6b&h=33f912d0&f=y&p=y
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
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Hi Martin,
My simple framework is one step above single-degree-of-freedom (SDOF), a 2
mass system. Please see for the following discussion:
https://www.acs.psu.edu/drussell/Demos/absorber/DynamicAbsorber.html
The animations are quite good. In the plot below, the dash-lines in the
main mass displacement show the SDOF response. With the additional dynamic
of the second mass, the solid lines show the two natural frequencies, one
above and below the SDOF. This might be analogous to your system where the
BS stiffness is the base spring and undescribed structure behaving like the
two mass or likely a more complicated version of it.
The pseudo-rigid body mode in this example dropped when the tuned mass was
added (solid to dash lines). That is why I suggested trying increasing the
BS stiffness to bring it up.
That said, the accuracy of the rest of the unsaid structure is equally
important as shown in the two mass example. Because dynamic boundary
conditions are highly uncertain, modal test with free-free boundary
condition is often done to correlate the structure before adding on the
actual boundary conditions experimentally and analytically. If your
structure is still instrumented, it's something to consider doing.
Best regards,
Jason
University of Minnesota
On Thu, Mar 30, 2023 at 10:13 AM <martin.mazurowski@drehmoment.de> wrote:
> Hi Jason,
>
> thanks for your Tip, increasing the E Module of the structure results with
> rigid body movement at ~90Hz as I would expect.
>
> I Will try your second tip with increasing the BS stiffnes.
>
> Can you recommend any literature / articles /web sites where I could go
> deeper into this topic?
> Because to be fair I'm a little bit lost.
>
> Mit freundlichen Grüßen,
>
> M. Eng. Martin Mazurowski
>
>
> Hauptstrasse 9
> D-86637 Wertingen
>
> FON: 08272 9952-29
> MOBIL: +49 157 581 577 83
> FAX: 08272 9952-99
> Mail: martin.mazurowski@drehmoment.de
> Web: www.drehmoment.de
>
> Geschäftsführer:
>
> Dipl.-Ing.(FH) Josef Hofer,
> B.Eng. Stefan Zobel,
> M.Eng. Martin Mazurowski
>
> Handelsregister Augsburg HRB 21452
>
> Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte
> Informationen enthalten. Wenn Sie nicht der richtige Adressat sind oder
> diese E-Mail irrtuemlich erhalten haben, informieren Sie bitte sofort den
> Absender und vernichten Sie diese E-Mail. Das unerlaubte Kopieren sowie die
> unbefugte Weitergabe dieser E-Mail ist nicht gestattet.
>
> This e-mail may contain confidential and/or privileged information. If you
> are not the intended recipient or have received this e-mail in error,
> please notify the sender immediately and destroy this e-mail. Any
> unauthorised copying, disclosure or distribution of the material in this
> e-mail is strictly forbidden.
> Please consider your environmental responsibility before printing this
> e-mail.
>
>
> -----Ursprüngliche Nachricht-----
> Von: Sze Kwan Cheah via Xansys <xansys-temp@list.xansys.org>
> Gesendet: Donnerstag, 30. März 2023 16:33
> An: XANSYS Mailing List Home <xansys-temp@list.xansys.org>
> Cc: Sze Kwan Cheah <cheah013@umn.edu>
> Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
>
> Mr. Mazurowski,
>
> I suspect the reason is because there is a coupling between the stiffness
> from the ball screw (BS) and the modes in the undescribed structure similar
> to a tuned-mass damper.
>
> To test this hypothesis, in your original model, if you set your structure
> to have an artificially large modulus of elasticity (e.g. 1000x), the 90Hz
> pseudo-rigid-body mode would appear as in your hand calculation.
>
> If the above is true, then it points to the hand calculation is inadequate
> in replicating the experiment. Counter-intuitively, try increasing the
> stiffness of the BS even higher than you have so far to hunt for the 90Hz
> mode.
>
>
> Good luck,
> Sze Kwan (Jason) Cheah
>
> Graduate Student
> University of Minnesota - Twin Cities
>
>
> On Thu, Mar 30, 2023 at 7:32 AM <martin.mazurowski@drehmoment.de> wrote:
>
> > Hello Mr. Testi,
> >
> > not in a practical way in my opinion.
> >
> > Mit freundlichen Grüßen,
> >
> > M. Eng. Martin Mazurowski
> >
> >
> > Hauptstrasse 9
> > D-86637 Wertingen
> >
> > FON: 08272 9952-29
> > MOBIL: +49 157 581 577 83
> > FAX: 08272 9952-99
> > Mail: martin.mazurowski@drehmoment.de
> > Web: www.drehmoment.de
> >
> > Geschäftsführer:
> >
> > Dipl.-Ing.(FH) Josef Hofer,
> > B.Eng. Stefan Zobel,
> > M.Eng. Martin Mazurowski
> >
> > Handelsregister Augsburg HRB 21452
> >
> > Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte
> > Informationen enthalten. Wenn Sie nicht der richtige Adressat sind
> > oder diese E-Mail irrtuemlich erhalten haben, informieren Sie bitte
> > sofort den Absender und vernichten Sie diese E-Mail. Das unerlaubte
> > Kopieren sowie die unbefugte Weitergabe dieser E-Mail ist nicht
> gestattet.
> >
> > This e-mail may contain confidential and/or privileged information. If
> > you are not the intended recipient or have received this e-mail in
> > error, please notify the sender immediately and destroy this e-mail.
> > Any unauthorised copying, disclosure or distribution of the material
> > in this e-mail is strictly forbidden.
> > Please consider your environmental responsibility before printing
> > this e-mail.
> >
> >
> > -----Ursprüngliche Nachricht-----
> > Von: Testi Riccardo <riccardo.testi@piaggio.com>
> > Gesendet: Donnerstag, 30. März 2023 14:06
> > An: XANSYS Mailing List Home <xansys-temp@list.xansys.org>
> > Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
> >
> > Dear Mr. Mazurowski,
> > in fact, I was referring to the physical bodies. Can their mass be
> > neglected while modelling and thus be substituted with purely elastic
> > entities, such as springs or bushings?
> >
> > Best regards
> > Riccardo Testi
> >
> > -----Original Message-----
> > From: martin.mazurowski@drehmoment.de
> > <martin.mazurowski@drehmoment.de>
> > Sent: giovedì 30 marzo 2023 09:04
> > To: 'XANSYS Mailing List Home' <xansys-temp@list.xansys.org>
> > Subject: [Xansys] Re: [Struct][Modal] Missing eigenmode.
> >
> > CAUTION:This email originated from outside the Piaggio Group. Do not
> > click links or open attachments unless you recognize the sender and
> > know the content is safe.
> >
> >
> > Dear Mr. Testi,
> >
> > you mean the Bushing/Spring elements used for the ball screw / guides?
> > Yes - those have 0 Mass.
> >
> > Mit freundlichen Grüßen,
> >
> > M. Eng. Martin Mazurowski
> >
> >
> > Hauptstrasse 9
> > D-86637 Wertingen
> >
> > FON: 08272 9952-29
> > MOBIL: +49 157 581 577 83
> > FAX: 08272 9952-99
> > Mail: martin.mazurowski@drehmoment.de
> > Web:
> > https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c82
> > b6b&h=33f912d0&f=y&p=y
> >
> > Geschäftsführer:
> >
> > Dipl.-Ing.(FH) Josef Hofer,
> > B.Eng. Stefan Zobel,
> > M.Eng. Martin Mazurowski
> >
> > Handelsregister Augsburg HRB 21452
> >
> > Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte
> > Informationen enthalten. Wenn Sie nicht der richtige Adressat sind
> > oder diese E-Mail irrtuemlich erhalten haben, informieren Sie bitte
> > sofort den Absender und vernichten Sie diese E-Mail. Das unerlaubte
> > Kopieren sowie die unbefugte Weitergabe dieser E-Mail ist nicht
> gestattet.
> >
> > This e-mail may contain confidential and/or privileged information. If
> > you are not the intended recipient or have received this e-mail in
> > error, please notify the sender immediately and destroy this e-mail.
> > Any unauthorised copying, disclosure or distribution of the material
> > in this e-mail is strictly forbidden.
> > Please consider your environmental responsibility before printing
> > this e-mail.
> >
> >
> > -----Ursprüngliche Nachricht-----
> > Von: Testi Riccardo <riccardo.testi@piaggio.com>
> > Gesendet: Donnerstag, 30. März 2023 08:56
> > An: XANSYS Mailing List Home <xansys-temp@list.xansys.org>
> > Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
> >
> > Dear Mr. Mazurowski,
> > is the mass of the things you simulated as purely elastic negligible
> > when compared to the mass of the rest of the structure?
> >
> > Best regards
> > Riccardo Testi
> > ---
> > Development and Strategies
> > 2 Wheeler Engines Technical Centre
> > Piaggio & C. S.p.A
> > Viale Rinaldo Piaggio, 25
> > 56025 Pontedera (Pisa) - ITALY
> > Phone: +39 0587 272850
> > Fax: +39 0587 272010
> > Mobile: +39 339 7241918
> > E-mail: riccardo.testi@piaggio.com
> >
> >
> >
> > -----Original Message-----
> > From: martin.mazurowski@drehmoment.de
> > <martin.mazurowski@drehmoment.de>
> > Sent: giovedì 30 marzo 2023 08:28
> > To: xansys-temp@list.xansys.org
> > Subject: [Xansys] [Struct][Modal] Missing eigenmode.
> >
> > CAUTION:This email originated from outside the Piaggio Group. Do not
> > click links or open attachments unless you recognize the sender and
> > know the content is safe.
> >
> >
> > Dear all,
> >
> >
> >
> > I have a problem here, I think I am missing something and I can't
> > understand what.
> >
> >
> >
> > I made a modal analysis of a structure and then it was tested - the
> > correlation between test and FEA was ok.
> >
> > Nevertheless, a mode was "not found".
> >
> >
> >
> > The structure is supported on guide carriages and is held in axial
> > direction by a ball screw. The stiffness of these parts is represented
> > with a bushing-like element.
> >
> > I suspected that the missing mode (at 90 Hz) is some kind of rigid
> > body motion due to the stiffness of the ball screw. When I calculate
> > the mass held and the stiffness of the ball screw by hand, I get the
> > ~90 Hz - so the assumption was probably correct.
> >
> >
> >
> > So I started to debug my model:
> >
> > If I set the ball screw stiffness to 0, I get a rigid body mode at 0
> > Hz - as I would expect.
> >
> >
> >
> > If I set the BS stiffness lower (using a hand calculation, I should
> > get 18Hz, for example), I get a result at 17.5Hz and a "rigid" motion
> > - OK, as expected.
> >
> >
> >
> > When I set BS stiffness higher, if axial motion mode is higher than
> > other modes, this mode is missing.... The first modes are at ~40-60Hz
> > and then I get modes at ~115 Hz.
> >
> > The 90Hz mode is never there and can't be noticed as clearly as when
> > the stiffness is set for results below 40Hz.
> >
> >
> >
> > Do you guys have any ideas? What am I missing?
> >
> > Thank you in advance for any tips!
> >
> >
> >
> > Best Regards,
> >
> >
> >
> > Mit freundlichen Grüßen,
> >
> >
> >
> > M. Eng. Martin Mazurowski
> >
> >
> >
> > Hauptstrasse 9
> >
> > D-86637 Wertingen
> >
> >
> >
> > FON: 08272 9952-29
> >
> > Mail: <mailto:martin.mazurowski@drehmoment.de>
> > martin.mazurowski@drehmoment.de
> >
> > Web: <
> > https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de%2F&e=e5
> > c82b6b&h=e5561f83&f=y&p=y>
> >
> > https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c82
> > b6b&h=33f912d0&f=y&p=y
> >
> >
> >
> > Geschäftsführer:
> >
> >
> >
> > Dipl.-Ing.(FH) Josef Hofer,
> > B.Eng. Stefan Zobel,
> >
> > M.Eng. Martin Mazurowski
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > _______________________________________________
> > Xansys mailing list -- xansys-temp@list.xansys.org To unsubscribe send
> > an email to xansys-temp-leave@list.xansys.org If you are receiving too
> > many emails from XANSYS please consider changing account settings to
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> >
> > Please send administrative requests such as deletion from XANSYS to
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> >
> >
> > _______________________________________________
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> >
> > _______________________________________________
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MM
martin.mazurowski@drehmoment.de
Thu, Mar 30, 2023 6:36 PM
Hi Jason,
thank you for your answers.
I made a lot of simulations today and now I understand why I don’t get the Mode at higher freq.
Now I suppose, that the vibration location is elsewhere.
But thank you once again - your tip moved me in the right direction.
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
MOBIL: +49 157 581 577 83
FAX: 08272 9952-99
Mail: martin.mazurowski@drehmoment.de
Web: www.drehmoment.de
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Handelsregister Augsburg HRB 21452
Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte Informationen enthalten. Wenn Sie nicht der richtige Adressat sind oder diese E-Mail irrtuemlich erhalten haben, informieren Sie bitte sofort den Absender und vernichten Sie diese E-Mail. Das unerlaubte Kopieren sowie die unbefugte Weitergabe dieser E-Mail ist nicht gestattet.
This e-mail may contain confidential and/or privileged information. If you are not the intended recipient or have received this e-mail in error, please notify the sender immediately and destroy this e-mail. Any unauthorised copying, disclosure or distribution of the material in this e-mail is strictly forbidden.
Please consider your environmental responsibility before printing this e-mail.
-----Ursprüngliche Nachricht-----
Von: Sze Kwan Cheah via Xansys xansys-temp@list.xansys.org
Gesendet: Donnerstag, 30. März 2023 20:27
An: XANSYS Mailing List Home xansys-temp@list.xansys.org
Cc: Sze Kwan Cheah cheah013@umn.edu
Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
Hi Martin,
My simple framework is one step above single-degree-of-freedom (SDOF), a 2 mass system. Please see for the following discussion:
https://www.acs.psu.edu/drussell/Demos/absorber/DynamicAbsorber.html
The animations are quite good. In the plot below, the dash-lines in the main mass displacement show the SDOF response. With the additional dynamic of the second mass, the solid lines show the two natural frequencies, one above and below the SDOF. This might be analogous to your system where the BS stiffness is the base spring and undescribed structure behaving like the two mass or likely a more complicated version of it.
The pseudo-rigid body mode in this example dropped when the tuned mass was added (solid to dash lines). That is why I suggested trying increasing the BS stiffness to bring it up.
That said, the accuracy of the rest of the unsaid structure is equally important as shown in the two mass example. Because dynamic boundary conditions are highly uncertain, modal test with free-free boundary condition is often done to correlate the structure before adding on the actual boundary conditions experimentally and analytically. If your structure is still instrumented, it's something to consider doing.
Best regards,
Jason
University of Minnesota
On Thu, Mar 30, 2023 at 10:13 AM martin.mazurowski@drehmoment.de wrote:
Hi Jason,
thanks for your Tip, increasing the E Module of the structure results
with rigid body movement at ~90Hz as I would expect.
I Will try your second tip with increasing the BS stiffnes.
Can you recommend any literature / articles /web sites where I could
go deeper into this topic?
Because to be fair I'm a little bit lost.
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
MOBIL: +49 157 581 577 83
FAX: 08272 9952-99
Mail: martin.mazurowski@drehmoment.de
Web: www.drehmoment.de
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Handelsregister Augsburg HRB 21452
Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte
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Kopieren sowie die unbefugte Weitergabe dieser E-Mail ist nicht gestattet.
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-----Ursprüngliche Nachricht-----
Von: Sze Kwan Cheah via Xansys xansys-temp@list.xansys.org
Gesendet: Donnerstag, 30. März 2023 16:33
An: XANSYS Mailing List Home xansys-temp@list.xansys.org
Cc: Sze Kwan Cheah cheah013@umn.edu
Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
Mr. Mazurowski,
I suspect the reason is because there is a coupling between the
stiffness from the ball screw (BS) and the modes in the undescribed
structure similar to a tuned-mass damper.
To test this hypothesis, in your original model, if you set your
structure to have an artificially large modulus of elasticity (e.g.
1000x), the 90Hz pseudo-rigid-body mode would appear as in your hand calculation.
If the above is true, then it points to the hand calculation is
inadequate in replicating the experiment. Counter-intuitively, try
increasing the stiffness of the BS even higher than you have so far to
hunt for the 90Hz mode.
Good luck,
Sze Kwan (Jason) Cheah
Graduate Student
University of Minnesota - Twin Cities
On Thu, Mar 30, 2023 at 7:32 AM martin.mazurowski@drehmoment.de wrote:
Hello Mr. Testi,
not in a practical way in my opinion.
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
MOBIL: +49 157 581 577 83
FAX: 08272 9952-99
Mail: martin.mazurowski@drehmoment.de
Web: www.drehmoment.de
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Handelsregister Augsburg HRB 21452
Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte
Informationen enthalten. Wenn Sie nicht der richtige Adressat sind
oder diese E-Mail irrtuemlich erhalten haben, informieren Sie bitte
sofort den Absender und vernichten Sie diese E-Mail. Das unerlaubte
Kopieren sowie die unbefugte Weitergabe dieser E-Mail ist nicht
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Please consider your environmental responsibility before printing
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-----Ursprüngliche Nachricht-----
Von: Testi Riccardo riccardo.testi@piaggio.com
Gesendet: Donnerstag, 30. März 2023 14:06
An: XANSYS Mailing List Home xansys-temp@list.xansys.org
Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
Dear Mr. Mazurowski,
in fact, I was referring to the physical bodies. Can their mass be
neglected while modelling and thus be substituted with purely
elastic entities, such as springs or bushings?
Best regards
Riccardo Testi
-----Original Message-----
From: martin.mazurowski@drehmoment.de
martin.mazurowski@drehmoment.de
Sent: giovedì 30 marzo 2023 09:04
To: 'XANSYS Mailing List Home' xansys-temp@list.xansys.org
Subject: [Xansys] Re: [Struct][Modal] Missing eigenmode.
CAUTION:This email originated from outside the Piaggio Group. Do not
click links or open attachments unless you recognize the sender and
know the content is safe.
Dear Mr. Testi,
you mean the Bushing/Spring elements used for the ball screw / guides?
Yes - those have 0 Mass.
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
MOBIL: +49 157 581 577 83
FAX: 08272 9952-99
Mail: martin.mazurowski@drehmoment.de
Web:
https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c
82
b6b&h=33f912d0&f=y&p=y
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Handelsregister Augsburg HRB 21452
Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte
Informationen enthalten. Wenn Sie nicht der richtige Adressat sind
oder diese E-Mail irrtuemlich erhalten haben, informieren Sie bitte
sofort den Absender und vernichten Sie diese E-Mail. Das unerlaubte
Kopieren sowie die unbefugte Weitergabe dieser E-Mail ist nicht
This e-mail may contain confidential and/or privileged information.
If you are not the intended recipient or have received this e-mail
in error, please notify the sender immediately and destroy this e-mail.
Any unauthorised copying, disclosure or distribution of the material
in this e-mail is strictly forbidden.
Please consider your environmental responsibility before printing
this e-mail.
-----Ursprüngliche Nachricht-----
Von: Testi Riccardo riccardo.testi@piaggio.com
Gesendet: Donnerstag, 30. März 2023 08:56
An: XANSYS Mailing List Home xansys-temp@list.xansys.org
Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
Dear Mr. Mazurowski,
is the mass of the things you simulated as purely elastic negligible
when compared to the mass of the rest of the structure?
Best regards
Riccardo Testi
Development and Strategies
2 Wheeler Engines Technical Centre
Piaggio & C. S.p.A
Viale Rinaldo Piaggio, 25
56025 Pontedera (Pisa) - ITALY
Phone: +39 0587 272850
Fax: +39 0587 272010
Mobile: +39 339 7241918
E-mail: riccardo.testi@piaggio.com
-----Original Message-----
From: martin.mazurowski@drehmoment.de
martin.mazurowski@drehmoment.de
Sent: giovedì 30 marzo 2023 08:28
To: xansys-temp@list.xansys.org
Subject: [Xansys] [Struct][Modal] Missing eigenmode.
CAUTION:This email originated from outside the Piaggio Group. Do not
click links or open attachments unless you recognize the sender and
know the content is safe.
Dear all,
I have a problem here, I think I am missing something and I can't
understand what.
I made a modal analysis of a structure and then it was tested - the
correlation between test and FEA was ok.
Nevertheless, a mode was "not found".
The structure is supported on guide carriages and is held in axial
direction by a ball screw. The stiffness of these parts is
represented with a bushing-like element.
I suspected that the missing mode (at 90 Hz) is some kind of rigid
body motion due to the stiffness of the ball screw. When I calculate
the mass held and the stiffness of the ball screw by hand, I get the
~90 Hz - so the assumption was probably correct.
So I started to debug my model:
If I set the ball screw stiffness to 0, I get a rigid body mode at 0
Hz - as I would expect.
If I set the BS stiffness lower (using a hand calculation, I should
get 18Hz, for example), I get a result at 17.5Hz and a "rigid"
motion
When I set BS stiffness higher, if axial motion mode is higher than
other modes, this mode is missing.... The first modes are at
~40-60Hz and then I get modes at ~115 Hz.
The 90Hz mode is never there and can't be noticed as clearly as when
the stiffness is set for results below 40Hz.
Do you guys have any ideas? What am I missing?
Thank you in advance for any tips!
Best Regards,
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
Mail: mailto:martin.mazurowski@drehmoment.de
martin.mazurowski@drehmoment.de
Web: <
https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de%2F&e=
e5
c82b6b&h=e5561f83&f=y&p=y>
https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c
82
b6b&h=33f912d0&f=y&p=y
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Xansys mailing list -- xansys-temp@list.xansys.org To unsubscribe
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Hi Jason,
thank you for your answers.
I made a lot of simulations today and now I understand why I don’t get the Mode at higher freq.
Now I suppose, that the vibration location is elsewhere.
But thank you once again - your tip moved me in the right direction.
Mit freundlichen Grüßen,
M. Eng. Martin Mazurowski
Hauptstrasse 9
D-86637 Wertingen
FON: 08272 9952-29
MOBIL: +49 157 581 577 83
FAX: 08272 9952-99
Mail: martin.mazurowski@drehmoment.de
Web: www.drehmoment.de
Geschäftsführer:
Dipl.-Ing.(FH) Josef Hofer,
B.Eng. Stefan Zobel,
M.Eng. Martin Mazurowski
Handelsregister Augsburg HRB 21452
Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte Informationen enthalten. Wenn Sie nicht der richtige Adressat sind oder diese E-Mail irrtuemlich erhalten haben, informieren Sie bitte sofort den Absender und vernichten Sie diese E-Mail. Das unerlaubte Kopieren sowie die unbefugte Weitergabe dieser E-Mail ist nicht gestattet.
This e-mail may contain confidential and/or privileged information. If you are not the intended recipient or have received this e-mail in error, please notify the sender immediately and destroy this e-mail. Any unauthorised copying, disclosure or distribution of the material in this e-mail is strictly forbidden.
Please consider your environmental responsibility before printing this e-mail.
-----Ursprüngliche Nachricht-----
Von: Sze Kwan Cheah via Xansys <xansys-temp@list.xansys.org>
Gesendet: Donnerstag, 30. März 2023 20:27
An: XANSYS Mailing List Home <xansys-temp@list.xansys.org>
Cc: Sze Kwan Cheah <cheah013@umn.edu>
Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
Hi Martin,
My simple framework is one step above single-degree-of-freedom (SDOF), a 2 mass system. Please see for the following discussion:
https://www.acs.psu.edu/drussell/Demos/absorber/DynamicAbsorber.html
The animations are quite good. In the plot below, the dash-lines in the main mass displacement show the SDOF response. With the additional dynamic of the second mass, the solid lines show the two natural frequencies, one above and below the SDOF. This might be analogous to your system where the BS stiffness is the base spring and undescribed structure behaving like the two mass or likely a more complicated version of it.
The pseudo-rigid body mode in this example dropped when the tuned mass was added (solid to dash lines). That is why I suggested trying increasing the BS stiffness to bring it up.
That said, the accuracy of the rest of the unsaid structure is equally important as shown in the two mass example. Because dynamic boundary conditions are highly uncertain, modal test with free-free boundary condition is often done to correlate the structure before adding on the actual boundary conditions experimentally and analytically. If your structure is still instrumented, it's something to consider doing.
Best regards,
Jason
University of Minnesota
On Thu, Mar 30, 2023 at 10:13 AM <martin.mazurowski@drehmoment.de> wrote:
> Hi Jason,
>
> thanks for your Tip, increasing the E Module of the structure results
> with rigid body movement at ~90Hz as I would expect.
>
> I Will try your second tip with increasing the BS stiffnes.
>
> Can you recommend any literature / articles /web sites where I could
> go deeper into this topic?
> Because to be fair I'm a little bit lost.
>
> Mit freundlichen Grüßen,
>
> M. Eng. Martin Mazurowski
>
>
> Hauptstrasse 9
> D-86637 Wertingen
>
> FON: 08272 9952-29
> MOBIL: +49 157 581 577 83
> FAX: 08272 9952-99
> Mail: martin.mazurowski@drehmoment.de
> Web: www.drehmoment.de
>
> Geschäftsführer:
>
> Dipl.-Ing.(FH) Josef Hofer,
> B.Eng. Stefan Zobel,
> M.Eng. Martin Mazurowski
>
> Handelsregister Augsburg HRB 21452
>
> Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte
> Informationen enthalten. Wenn Sie nicht der richtige Adressat sind
> oder diese E-Mail irrtuemlich erhalten haben, informieren Sie bitte
> sofort den Absender und vernichten Sie diese E-Mail. Das unerlaubte
> Kopieren sowie die unbefugte Weitergabe dieser E-Mail ist nicht gestattet.
>
> This e-mail may contain confidential and/or privileged information. If
> you are not the intended recipient or have received this e-mail in
> error, please notify the sender immediately and destroy this e-mail.
> Any unauthorised copying, disclosure or distribution of the material
> in this e-mail is strictly forbidden.
> Please consider your environmental responsibility before printing
> this e-mail.
>
>
> -----Ursprüngliche Nachricht-----
> Von: Sze Kwan Cheah via Xansys <xansys-temp@list.xansys.org>
> Gesendet: Donnerstag, 30. März 2023 16:33
> An: XANSYS Mailing List Home <xansys-temp@list.xansys.org>
> Cc: Sze Kwan Cheah <cheah013@umn.edu>
> Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
>
> Mr. Mazurowski,
>
> I suspect the reason is because there is a coupling between the
> stiffness from the ball screw (BS) and the modes in the undescribed
> structure similar to a tuned-mass damper.
>
> To test this hypothesis, in your original model, if you set your
> structure to have an artificially large modulus of elasticity (e.g.
> 1000x), the 90Hz pseudo-rigid-body mode would appear as in your hand calculation.
>
> If the above is true, then it points to the hand calculation is
> inadequate in replicating the experiment. Counter-intuitively, try
> increasing the stiffness of the BS even higher than you have so far to
> hunt for the 90Hz mode.
>
>
> Good luck,
> Sze Kwan (Jason) Cheah
>
> Graduate Student
> University of Minnesota - Twin Cities
>
>
> On Thu, Mar 30, 2023 at 7:32 AM <martin.mazurowski@drehmoment.de> wrote:
>
> > Hello Mr. Testi,
> >
> > not in a practical way in my opinion.
> >
> > Mit freundlichen Grüßen,
> >
> > M. Eng. Martin Mazurowski
> >
> >
> > Hauptstrasse 9
> > D-86637 Wertingen
> >
> > FON: 08272 9952-29
> > MOBIL: +49 157 581 577 83
> > FAX: 08272 9952-99
> > Mail: martin.mazurowski@drehmoment.de
> > Web: www.drehmoment.de
> >
> > Geschäftsführer:
> >
> > Dipl.-Ing.(FH) Josef Hofer,
> > B.Eng. Stefan Zobel,
> > M.Eng. Martin Mazurowski
> >
> > Handelsregister Augsburg HRB 21452
> >
> > Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte
> > Informationen enthalten. Wenn Sie nicht der richtige Adressat sind
> > oder diese E-Mail irrtuemlich erhalten haben, informieren Sie bitte
> > sofort den Absender und vernichten Sie diese E-Mail. Das unerlaubte
> > Kopieren sowie die unbefugte Weitergabe dieser E-Mail ist nicht
> gestattet.
> >
> > This e-mail may contain confidential and/or privileged information.
> > If you are not the intended recipient or have received this e-mail
> > in error, please notify the sender immediately and destroy this e-mail.
> > Any unauthorised copying, disclosure or distribution of the material
> > in this e-mail is strictly forbidden.
> > Please consider your environmental responsibility before printing
> > this e-mail.
> >
> >
> > -----Ursprüngliche Nachricht-----
> > Von: Testi Riccardo <riccardo.testi@piaggio.com>
> > Gesendet: Donnerstag, 30. März 2023 14:06
> > An: XANSYS Mailing List Home <xansys-temp@list.xansys.org>
> > Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
> >
> > Dear Mr. Mazurowski,
> > in fact, I was referring to the physical bodies. Can their mass be
> > neglected while modelling and thus be substituted with purely
> > elastic entities, such as springs or bushings?
> >
> > Best regards
> > Riccardo Testi
> >
> > -----Original Message-----
> > From: martin.mazurowski@drehmoment.de
> > <martin.mazurowski@drehmoment.de>
> > Sent: giovedì 30 marzo 2023 09:04
> > To: 'XANSYS Mailing List Home' <xansys-temp@list.xansys.org>
> > Subject: [Xansys] Re: [Struct][Modal] Missing eigenmode.
> >
> > CAUTION:This email originated from outside the Piaggio Group. Do not
> > click links or open attachments unless you recognize the sender and
> > know the content is safe.
> >
> >
> > Dear Mr. Testi,
> >
> > you mean the Bushing/Spring elements used for the ball screw / guides?
> > Yes - those have 0 Mass.
> >
> > Mit freundlichen Grüßen,
> >
> > M. Eng. Martin Mazurowski
> >
> >
> > Hauptstrasse 9
> > D-86637 Wertingen
> >
> > FON: 08272 9952-29
> > MOBIL: +49 157 581 577 83
> > FAX: 08272 9952-99
> > Mail: martin.mazurowski@drehmoment.de
> > Web:
> > https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c
> > 82
> > b6b&h=33f912d0&f=y&p=y
> >
> > Geschäftsführer:
> >
> > Dipl.-Ing.(FH) Josef Hofer,
> > B.Eng. Stefan Zobel,
> > M.Eng. Martin Mazurowski
> >
> > Handelsregister Augsburg HRB 21452
> >
> > Diese E-Mail kann vertrauliche und/oder rechtlich geschuetzte
> > Informationen enthalten. Wenn Sie nicht der richtige Adressat sind
> > oder diese E-Mail irrtuemlich erhalten haben, informieren Sie bitte
> > sofort den Absender und vernichten Sie diese E-Mail. Das unerlaubte
> > Kopieren sowie die unbefugte Weitergabe dieser E-Mail ist nicht
> gestattet.
> >
> > This e-mail may contain confidential and/or privileged information.
> > If you are not the intended recipient or have received this e-mail
> > in error, please notify the sender immediately and destroy this e-mail.
> > Any unauthorised copying, disclosure or distribution of the material
> > in this e-mail is strictly forbidden.
> > Please consider your environmental responsibility before printing
> > this e-mail.
> >
> >
> > -----Ursprüngliche Nachricht-----
> > Von: Testi Riccardo <riccardo.testi@piaggio.com>
> > Gesendet: Donnerstag, 30. März 2023 08:56
> > An: XANSYS Mailing List Home <xansys-temp@list.xansys.org>
> > Betreff: [Xansys] Re: [Struct][Modal] Missing eigenmode.
> >
> > Dear Mr. Mazurowski,
> > is the mass of the things you simulated as purely elastic negligible
> > when compared to the mass of the rest of the structure?
> >
> > Best regards
> > Riccardo Testi
> > ---
> > Development and Strategies
> > 2 Wheeler Engines Technical Centre
> > Piaggio & C. S.p.A
> > Viale Rinaldo Piaggio, 25
> > 56025 Pontedera (Pisa) - ITALY
> > Phone: +39 0587 272850
> > Fax: +39 0587 272010
> > Mobile: +39 339 7241918
> > E-mail: riccardo.testi@piaggio.com
> >
> >
> >
> > -----Original Message-----
> > From: martin.mazurowski@drehmoment.de
> > <martin.mazurowski@drehmoment.de>
> > Sent: giovedì 30 marzo 2023 08:28
> > To: xansys-temp@list.xansys.org
> > Subject: [Xansys] [Struct][Modal] Missing eigenmode.
> >
> > CAUTION:This email originated from outside the Piaggio Group. Do not
> > click links or open attachments unless you recognize the sender and
> > know the content is safe.
> >
> >
> > Dear all,
> >
> >
> >
> > I have a problem here, I think I am missing something and I can't
> > understand what.
> >
> >
> >
> > I made a modal analysis of a structure and then it was tested - the
> > correlation between test and FEA was ok.
> >
> > Nevertheless, a mode was "not found".
> >
> >
> >
> > The structure is supported on guide carriages and is held in axial
> > direction by a ball screw. The stiffness of these parts is
> > represented with a bushing-like element.
> >
> > I suspected that the missing mode (at 90 Hz) is some kind of rigid
> > body motion due to the stiffness of the ball screw. When I calculate
> > the mass held and the stiffness of the ball screw by hand, I get the
> > ~90 Hz - so the assumption was probably correct.
> >
> >
> >
> > So I started to debug my model:
> >
> > If I set the ball screw stiffness to 0, I get a rigid body mode at 0
> > Hz - as I would expect.
> >
> >
> >
> > If I set the BS stiffness lower (using a hand calculation, I should
> > get 18Hz, for example), I get a result at 17.5Hz and a "rigid"
> > motion
> > - OK, as expected.
> >
> >
> >
> > When I set BS stiffness higher, if axial motion mode is higher than
> > other modes, this mode is missing.... The first modes are at
> > ~40-60Hz and then I get modes at ~115 Hz.
> >
> > The 90Hz mode is never there and can't be noticed as clearly as when
> > the stiffness is set for results below 40Hz.
> >
> >
> >
> > Do you guys have any ideas? What am I missing?
> >
> > Thank you in advance for any tips!
> >
> >
> >
> > Best Regards,
> >
> >
> >
> > Mit freundlichen Grüßen,
> >
> >
> >
> > M. Eng. Martin Mazurowski
> >
> >
> >
> > Hauptstrasse 9
> >
> > D-86637 Wertingen
> >
> >
> >
> > FON: 08272 9952-29
> >
> > Mail: <mailto:martin.mazurowski@drehmoment.de>
> > martin.mazurowski@drehmoment.de
> >
> > Web: <
> > https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de%2F&e=
> > e5
> > c82b6b&h=e5561f83&f=y&p=y>
> >
> > https://urlsand.esvalabs.com/?u=http%3A%2F%2Fwww.drehmoment.de&e=e5c
> > 82
> > b6b&h=33f912d0&f=y&p=y
> >
> >
> >
> > Geschäftsführer:
> >
> >
> >
> > Dipl.-Ing.(FH) Josef Hofer,
> > B.Eng. Stefan Zobel,
> >
> > M.Eng. Martin Mazurowski
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > _______________________________________________
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_______________________________________________
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