Empathy List Archives

PJ

Patterson, James

Thu, Aug 31, 2023 8:18 PM

Hi,

A colleague pointed out to me that in the PLNSOL dbox there is an option for "von Mises Plastic Strain" as well as "Equivalent Plastic Strain". I'm RTFM-ing, but am struggling to find a definition for a difference between these. I do see this in the theory Ref., which is nothing but more confusing...

17.10. POST1 and POST26 - Interpretation of Equivalent Strains
The equivalent strains for the elastic, plastic, creep, and thermal strains are calculated in postprocessing using the von Mises equation:
Thoughts?

Thanks,

Jim

[cid:image001.png@01D9DC26.C0643180]
James J. Patterson, PhD.
Principal Vehicle Systems Engineer
Trailer Commercial Vehicle Systems
2070 Industrial Place S.E. Canton, OH 44707
ph. 330 489 0095 | fax 330 489 1961
jpatterson@hendrickson-intl.com mailto:jpatterson@hendrickson-intl.com
www.hendrickson-intl.com
[cid:image002.gif@01D9DC26.C0643180]

The contents of this message may be privileged and confidential. Therefore, if this message has been received in error, please delete it without reading it. Your receipt of this message is not intended to waive any applicable privilege. Please do not disseminate this message without the permission of the author.

Hi, A colleague pointed out to me that in the PLNSOL dbox there is an option for "von Mises Plastic Strain" as well as "Equivalent Plastic Strain". I'm RTFM-ing, but am struggling to find a definition for a difference between these. I do see this in the theory Ref., which is nothing but more confusing... 17.10. POST1 and POST26 - Interpretation of Equivalent Strains The equivalent strains for the elastic, plastic, creep, and thermal strains are calculated in postprocessing using the von Mises equation: Thoughts? Thanks, Jim [cid:image001.png@01D9DC26.C0643180] James J. Patterson, PhD. Principal Vehicle Systems Engineer Trailer Commercial Vehicle Systems 2070 Industrial Place S.E. Canton, OH 44707 ph. 330 489 0095 | fax 330 489 1961 jpatterson@hendrickson-intl.com<mailto:jpatterson@hendrickson-intl.com> www.hendrickson-intl.com [cid:image002.gif@01D9DC26.C0643180] The contents of this message may be privileged and confidential. Therefore, if this message has been received in error, please delete it without reading it. Your receipt of this message is not intended to waive any applicable privilege. Please do not disseminate this message without the permission of the author.

BD

Bohlen, Dan (GE Aerospace, US)

Thu, Sep 7, 2023 2:29 PM

Makes two of us who have wondered what the difference is....

Dan Mr.vonMiseswasveryeffective Bohlen
Senior Engineer, Stress Analysis
STAR review chairman, military structures
NGP2 engine focal
GE Aerospace
1 Neumann Way
Evendale, OH 45215 USA

Build B90 Col. H5 cube BK35-251
M/D H358 Cell 513-917-3402

Building 200 Col. G3 cube BC088 Desk Phone 3-8816

GE FOCUS: Safety, Quality, Delivery, Cost

"In God we trust, all others bring data." W Edwards Deming

-----Original Message-----
From: Patterson, James jpatterson@hendrickson-intl.com
Sent: Thursday, August 31, 2023 4:18 PM
To: xansys-temp@list.xansys.org
Subject: EXT: [Xansys] von Mises Plastic Strain vs. Equivalent Plastic Strain...

WARNING: This email originated from outside of GE. Please validate the sender's email address before clicking on links or attachments as they may not be safe.

Hi,

A colleague pointed out to me that in the PLNSOL dbox there is an option for "von Mises Plastic Strain" as well as "Equivalent Plastic Strain". I'm RTFM-ing, but am struggling to find a definition for a difference between these. I do see this in the theory Ref., which is nothing but more confusing...

17.10. POST1 and POST26 - Interpretation of Equivalent Strains The equivalent strains for the elastic, plastic, creep, and thermal strains are calculated in postprocessing using the von Mises equation:
Thoughts?

Thanks,

Jim

[cid:image001.png@01D9DC26.C0643180]
James J. Patterson, PhD.
Principal Vehicle Systems Engineer
Trailer Commercial Vehicle Systems
2070 Industrial Place S.E. Canton, OH 44707
ph. 330 489 0095 | fax 330 489 1961
jpatterson@hendrickson-intl.com mailto:jpatterson@hendrickson-intl.com
www.hendrickson-intl.com
[cid:image002.gif@01D9DC26.C0643180]

The contents of this message may be privileged and confidential. Therefore, if this message has been received in error, please delete it without reading it. Your receipt of this message is not intended to waive any applicable privilege. Please do not disseminate this message without the permission of the author.

Makes two of us who have wondered what the difference is.... Dan Mr.vonMiseswasveryeffective Bohlen Senior Engineer, Stress Analysis STAR review chairman, military structures NGP2 engine focal GE Aerospace 1 Neumann Way Evendale, OH 45215 USA Build B90 Col. H5 cube BK35-251 M/D H358 Cell 513-917-3402 Building 200 Col. G3 cube BC088 Desk Phone 3-8816 GE FOCUS: Safety, Quality, Delivery, Cost "In God we trust, all others bring data." W Edwards Deming -----Original Message----- From: Patterson, James <jpatterson@hendrickson-intl.com> Sent: Thursday, August 31, 2023 4:18 PM To: xansys-temp@list.xansys.org Subject: EXT: [Xansys] von Mises Plastic Strain vs. Equivalent Plastic Strain... WARNING: This email originated from outside of GE. Please validate the sender's email address before clicking on links or attachments as they may not be safe. Hi, A colleague pointed out to me that in the PLNSOL dbox there is an option for "von Mises Plastic Strain" as well as "Equivalent Plastic Strain". I'm RTFM-ing, but am struggling to find a definition for a difference between these. I do see this in the theory Ref., which is nothing but more confusing... 17.10. POST1 and POST26 - Interpretation of Equivalent Strains The equivalent strains for the elastic, plastic, creep, and thermal strains are calculated in postprocessing using the von Mises equation: Thoughts? Thanks, Jim [cid:image001.png@01D9DC26.C0643180] James J. Patterson, PhD. Principal Vehicle Systems Engineer Trailer Commercial Vehicle Systems 2070 Industrial Place S.E. Canton, OH 44707 ph. 330 489 0095 | fax 330 489 1961 jpatterson@hendrickson-intl.com<mailto:jpatterson@hendrickson-intl.com> www.hendrickson-intl.com [cid:image002.gif@01D9DC26.C0643180] The contents of this message may be privileged and confidential. Therefore, if this message has been received in error, please delete it without reading it. Your receipt of this message is not intended to waive any applicable privilege. Please do not disseminate this message without the permission of the author.

B

Barry

Thu, Sep 7, 2023 2:57 PM

I am only guessing, perhaps one is the equivalent plastic strain (instantaneous) and the other is the plastic strain magnitude. In Abaqus the equivalent quantities are PEEQ and PEMAG. For proportional loading they will be the same.

Regards, B

-----Original Message-----
From: Bohlen, Dan (GE Aerospace, US) dan.bohlen@ge.com
Sent: Thursday, September 7, 2023 3:29 PM
To: XANSYS Mailing List Home xansys-temp@list.xansys.org
Subject: [Xansys] Re: von Mises Plastic Strain vs. Equivalent Plastic Strain...

Makes two of us who have wondered what the difference is....

Dan Mr.vonMiseswasveryeffective Bohlen
Senior Engineer, Stress Analysis
STAR review chairman, military structures
NGP2 engine focal
GE Aerospace
1 Neumann Way
Evendale, OH 45215 USA

Build B90 Col. H5 cube BK35-251
M/D H358 Cell 513-917-3402

Building 200 Col. G3 cube BC088 Desk Phone 3-8816

GE FOCUS: Safety, Quality, Delivery, Cost

"In God we trust, all others bring data." W Edwards Deming

-----Original Message-----
From: Patterson, James jpatterson@hendrickson-intl.com
Sent: Thursday, August 31, 2023 4:18 PM
To: xansys-temp@list.xansys.org
Subject: EXT: [Xansys] von Mises Plastic Strain vs. Equivalent Plastic Strain...

WARNING: This email originated from outside of GE. Please validate the sender's email address before clicking on links or attachments as they may not be safe.

Hi,

A colleague pointed out to me that in the PLNSOL dbox there is an option for "von Mises Plastic Strain" as well as "Equivalent Plastic Strain". I'm RTFM-ing, but am struggling to find a definition for a difference between these. I do see this in the theory Ref., which is nothing but more confusing...

17.10. POST1 and POST26 - Interpretation of Equivalent Strains The equivalent strains for the elastic, plastic, creep, and thermal strains are calculated in postprocessing using the von Mises equation:
Thoughts?

Thanks,

Jim

[cid:image001.png@01D9DC26.C0643180]
James J. Patterson, PhD.
Principal Vehicle Systems Engineer
Trailer Commercial Vehicle Systems
2070 Industrial Place S.E. Canton, OH 44707
ph. 330 489 0095 | fax 330 489 1961
jpatterson@hendrickson-intl.com mailto:jpatterson@hendrickson-intl.com
www.hendrickson-intl.com
[cid:image002.gif@01D9DC26.C0643180]

The contents of this message may be privileged and confidential. Therefore, if this message has been received in error, please delete it without reading it. Your receipt of this message is not intended to waive any applicable privilege. Please do not disseminate this message without the permission of the author.

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

I am only guessing, perhaps one is the equivalent plastic strain (instantaneous) and the other is the plastic strain magnitude. In Abaqus the equivalent quantities are PEEQ and PEMAG. For proportional loading they will be the same. Regards, B -----Original Message----- From: Bohlen, Dan (GE Aerospace, US) <dan.bohlen@ge.com> Sent: Thursday, September 7, 2023 3:29 PM To: XANSYS Mailing List Home <xansys-temp@list.xansys.org> Subject: [Xansys] Re: von Mises Plastic Strain vs. Equivalent Plastic Strain... Makes two of us who have wondered what the difference is.... Dan Mr.vonMiseswasveryeffective Bohlen Senior Engineer, Stress Analysis STAR review chairman, military structures NGP2 engine focal GE Aerospace 1 Neumann Way Evendale, OH 45215 USA Build B90 Col. H5 cube BK35-251 M/D H358 Cell 513-917-3402 Building 200 Col. G3 cube BC088 Desk Phone 3-8816 GE FOCUS: Safety, Quality, Delivery, Cost "In God we trust, all others bring data." W Edwards Deming -----Original Message----- From: Patterson, James <jpatterson@hendrickson-intl.com> Sent: Thursday, August 31, 2023 4:18 PM To: xansys-temp@list.xansys.org Subject: EXT: [Xansys] von Mises Plastic Strain vs. Equivalent Plastic Strain... WARNING: This email originated from outside of GE. Please validate the sender's email address before clicking on links or attachments as they may not be safe. Hi, A colleague pointed out to me that in the PLNSOL dbox there is an option for "von Mises Plastic Strain" as well as "Equivalent Plastic Strain". I'm RTFM-ing, but am struggling to find a definition for a difference between these. I do see this in the theory Ref., which is nothing but more confusing... 17.10. POST1 and POST26 - Interpretation of Equivalent Strains The equivalent strains for the elastic, plastic, creep, and thermal strains are calculated in postprocessing using the von Mises equation: Thoughts? Thanks, Jim [cid:image001.png@01D9DC26.C0643180] James J. Patterson, PhD. Principal Vehicle Systems Engineer Trailer Commercial Vehicle Systems 2070 Industrial Place S.E. Canton, OH 44707 ph. 330 489 0095 | fax 330 489 1961 jpatterson@hendrickson-intl.com<mailto:jpatterson@hendrickson-intl.com> www.hendrickson-intl.com [cid:image002.gif@01D9DC26.C0643180] The contents of this message may be privileged and confidential. Therefore, if this message has been received in error, please delete it without reading it. Your receipt of this message is not intended to waive any applicable privilege. Please do not disseminate this message without the permission of the author. _______________________________________________ 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, Sep 7, 2023 3:08 PM

I, in fact, raised this question long time ago but didn’t get too many
responses. The issue was regarding the difference between equivalent
“stress” and the von Mises “stress”. I read TFM but couldn’t get anything
useful.

Regards,
MG

--

---====
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

---====

I, in fact, raised this question long time ago but didn’t get too many responses. The issue was regarding the difference between equivalent “stress” and the von Mises “stress”. I read TFM but couldn’t get anything useful. Regards, MG -- ===================================== 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 =====================================

SM

Santhosh M

Fri, Sep 8, 2023 3:12 AM

PLNSOL dbox there is an option for "von Mises Plastic Strain" as well as "Equivalent Plastic Strain".

Below are the two plastic strains available under PLNSOL

PLNSOL, EPPL,EQV ( Main Menu > Post Processing > Plot Results > Contour Plot > Nodal Solu > Plastic Strain > Von Mises Plastic Strain)
PLNSOL, NL,EPEQ, 0,1.0 ( Main Menu > Post Processing > Plot Results > Contour Plot > Nodal Solu > Plastic Strain > Accumulated Equivalent Plastic Strain) ( It is actually named as ACCUMULATED Equivalent Plastic Strain not just Equivalent Plastic Strain)

The difference between EPPL,EQV (current equivalent plastic strain) and NL,EPEQ (accumulated equivalent plastic strain) can be explained with an example:

For monotonic, proportional loading, the values of EPPL,EQV and NL,EPEQ will basically be the same. The main difference between the two will be observed for cases involving cyclic loading.

Imagine a uniaxial specimen that undergoes cyclic loading such that it has plastic straining in tension and compression. This will basically traverse the cyclic stress-strain history where plastic strain will increase, then decrease to zero in reverse loading, then increase again, etc. This equivalent plastic strain is EPPL,EQV.

However, if we look at it from the perspective of the damage of the material, the equivalent plastic strain decreasing gives the wrong impression. Hence, NL,EPEQ always increases, and it represents the accumulation of plastic strains during the entire load history (it is always increasing and positive).

Hence, in the case of the uniaxial specimen, after compressing the rod to "recover" the plastic strain, EPPL,EQV would show 0 strain while NL,EPEQ would show 2*max_plastic_strain since NL,EPEQ is accumulated (NL,EPEQ is often used in damage calculations).

Regards,
Santhosh M
ANSYS India / Bangalore.

-----Original Message-----
From: Barry barry@odcs.ltd.uk
Sent: Thursday, September 7, 2023 8:28 PM
To: XANSYS Mailing List Home xansys-temp@list.xansys.org
Subject: [Xansys] Re: von Mises Plastic Strain vs. Equivalent Plastic Strain...

[External Sender]

I am only guessing, perhaps one is the equivalent plastic strain (instantaneous) and the other is the plastic strain magnitude. In Abaqus the equivalent quantities are PEEQ and PEMAG. For proportional loading they will be the same.

Regards, B

-----Original Message-----
From: Bohlen, Dan (GE Aerospace, US) dan.bohlen@ge.com
Sent: Thursday, September 7, 2023 3:29 PM
To: XANSYS Mailing List Home xansys-temp@list.xansys.org
Subject: [Xansys] Re: von Mises Plastic Strain vs. Equivalent Plastic Strain...

Makes two of us who have wondered what the difference is....

Dan Mr.vonMiseswasveryeffective Bohlen
Senior Engineer, Stress Analysis
STAR review chairman, military structures
NGP2 engine focal
GE Aerospace
1 Neumann Way
Evendale, OH 45215 USA

Build B90 Col. H5 cube BK35-251
M/D H358 Cell 513-917-3402

Building 200 Col. G3 cube BC088 Desk Phone 3-8816

GE FOCUS: Safety, Quality, Delivery, Cost

"In God we trust, all others bring data." W Edwards Deming

-----Original Message-----
From: Patterson, James jpatterson@hendrickson-intl.com
Sent: Thursday, August 31, 2023 4:18 PM
To: xansys-temp@list.xansys.org
Subject: EXT: [Xansys] von Mises Plastic Strain vs. Equivalent Plastic Strain...

WARNING: This email originated from outside of GE. Please validate the sender's email address before clicking on links or attachments as they may not be safe.

Hi,

A colleague pointed out to me that in the PLNSOL dbox there is an option for "von Mises Plastic Strain" as well as "Equivalent Plastic Strain". I'm RTFM-ing, but am struggling to find a definition for a difference between these. I do see this in the theory Ref., which is nothing but more confusing...

17.10. POST1 and POST26 - Interpretation of Equivalent Strains The equivalent strains for the elastic, plastic, creep, and thermal strains are calculated in postprocessing using the von Mises equation:
Thoughts?

Thanks,

Jim

[cid:image001.png@01D9DC26.C0643180]
James J. Patterson, PhD.
Principal Vehicle Systems Engineer
Trailer Commercial Vehicle Systems
2070 Industrial Place S.E. Canton, OH 44707
ph. 330 489 0095 | fax 330 489 1961
jpatterson@hendrickson-intl.com mailto:jpatterson@hendrickson-intl.com
www.hendrickson-intl.com
[cid:image002.gif@01D9DC26.C0643180]

The contents of this message may be privileged and confidential. Therefore, if this message has been received in error, please delete it without reading it. Your receipt of this message is not intended to waive any applicable privilege. Please do not disseminate this message without the permission of the author.

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

>> PLNSOL dbox there is an option for "von Mises Plastic Strain" as well as "Equivalent Plastic Strain". Below are the two plastic strains available under PLNSOL 1. PLNSOL, EPPL,EQV ( Main Menu > Post Processing > Plot Results > Contour Plot > Nodal Solu > Plastic Strain > Von Mises Plastic Strain) 2. PLNSOL, NL,EPEQ, 0,1.0 ( Main Menu > Post Processing > Plot Results > Contour Plot > Nodal Solu > Plastic Strain > Accumulated Equivalent Plastic Strain) ( It is actually named as ACCUMULATED Equivalent Plastic Strain not just Equivalent Plastic Strain) The difference between EPPL,EQV (current equivalent plastic strain) and NL,EPEQ (accumulated equivalent plastic strain) can be explained with an example: For monotonic, proportional loading, the values of EPPL,EQV and NL,EPEQ will basically be the same. The main difference between the two will be observed for cases involving cyclic loading. Imagine a uniaxial specimen that undergoes cyclic loading such that it has plastic straining in tension and compression. This will basically traverse the cyclic stress-strain history where plastic strain will increase, then decrease to zero in reverse loading, then increase again, etc. This equivalent plastic strain is EPPL,EQV. However, if we look at it from the perspective of the damage of the material, the equivalent plastic strain decreasing gives the wrong impression. Hence, NL,EPEQ always increases, and it represents the accumulation of plastic strains during the entire load history (it is always increasing and positive). Hence, in the case of the uniaxial specimen, after compressing the rod to "recover" the plastic strain, EPPL,EQV would show 0 strain while NL,EPEQ would show 2*max_plastic_strain since NL,EPEQ is accumulated (NL,EPEQ is often used in damage calculations). ------------------------------------- Regards, Santhosh M ANSYS India / Bangalore. -----Original Message----- From: Barry <barry@odcs.ltd.uk> Sent: Thursday, September 7, 2023 8:28 PM To: XANSYS Mailing List Home <xansys-temp@list.xansys.org> Subject: [Xansys] Re: von Mises Plastic Strain vs. Equivalent Plastic Strain... [External Sender] I am only guessing, perhaps one is the equivalent plastic strain (instantaneous) and the other is the plastic strain magnitude. In Abaqus the equivalent quantities are PEEQ and PEMAG. For proportional loading they will be the same. Regards, B -----Original Message----- From: Bohlen, Dan (GE Aerospace, US) <dan.bohlen@ge.com> Sent: Thursday, September 7, 2023 3:29 PM To: XANSYS Mailing List Home <xansys-temp@list.xansys.org> Subject: [Xansys] Re: von Mises Plastic Strain vs. Equivalent Plastic Strain... Makes two of us who have wondered what the difference is.... Dan Mr.vonMiseswasveryeffective Bohlen Senior Engineer, Stress Analysis STAR review chairman, military structures NGP2 engine focal GE Aerospace 1 Neumann Way Evendale, OH 45215 USA Build B90 Col. H5 cube BK35-251 M/D H358 Cell 513-917-3402 Building 200 Col. G3 cube BC088 Desk Phone 3-8816 GE FOCUS: Safety, Quality, Delivery, Cost "In God we trust, all others bring data." W Edwards Deming -----Original Message----- From: Patterson, James <jpatterson@hendrickson-intl.com> Sent: Thursday, August 31, 2023 4:18 PM To: xansys-temp@list.xansys.org Subject: EXT: [Xansys] von Mises Plastic Strain vs. Equivalent Plastic Strain... WARNING: This email originated from outside of GE. Please validate the sender's email address before clicking on links or attachments as they may not be safe. Hi, A colleague pointed out to me that in the PLNSOL dbox there is an option for "von Mises Plastic Strain" as well as "Equivalent Plastic Strain". I'm RTFM-ing, but am struggling to find a definition for a difference between these. I do see this in the theory Ref., which is nothing but more confusing... 17.10. POST1 and POST26 - Interpretation of Equivalent Strains The equivalent strains for the elastic, plastic, creep, and thermal strains are calculated in postprocessing using the von Mises equation: Thoughts? Thanks, Jim [cid:image001.png@01D9DC26.C0643180] James J. Patterson, PhD. Principal Vehicle Systems Engineer Trailer Commercial Vehicle Systems 2070 Industrial Place S.E. Canton, OH 44707 ph. 330 489 0095 | fax 330 489 1961 jpatterson@hendrickson-intl.com<mailto:jpatterson@hendrickson-intl.com> www.hendrickson-intl.com [cid:image002.gif@01D9DC26.C0643180] The contents of this message may be privileged and confidential. Therefore, if this message has been received in error, please delete it without reading it. Your receipt of this message is not intended to waive any applicable privilege. Please do not disseminate this message without the permission of the author. _______________________________________________ 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