Empathy List Archives

A2

arsalaan_2020bciv010@nitsri.ac.in

Mon, Jan 8, 2024 6:25 PM

Dear XANSYS community,

I am an undergraduate student in the final year of my program, and I am currently working on a project that involves using ANSYS APDL. I have created an area using bsplines and lines utilizing the area command. However, I received a warning indicating that the lines do not lie on common coordinate value in the currently active coordinate system, and a Coons patch is being fitted between them. I would appreciate it if you could provide more information or guidance on how to resolve this issue. Additionally, I am curious to learn more about the concept of Coons patch in the context of ANSYS APDL. Any insights or documentation you can share on this matter would be highly beneficial for my project. For reference, I have attached a snippet of the warning message to this email.

I would greatly appreciate any guidance, best practices, or recommended techniques that could help me achieve this objective more efficiently.

Thank you,

Arsalaan Reyaz

Undergraduate student, N.I.T Srinagar, India

Dear XANSYS community, I am an undergraduate student in the final year of my program, and I am currently working on a project that involves using ANSYS APDL. I have created an area using bsplines and lines utilizing the area command. However, I received a warning indicating that the lines do not lie on common coordinate value in the currently active coordinate system, and a Coons patch is being fitted between them. I would appreciate it if you could provide more information or guidance on how to resolve this issue. Additionally, I am curious to learn more about the concept of Coons patch in the context of ANSYS APDL. Any insights or documentation you can share on this matter would be highly beneficial for my project. For reference, I have attached a snippet of the warning message to this email. I would greatly appreciate any guidance, best practices, or recommended techniques that could help me achieve this objective more efficiently. Thank you, Arsalaan Reyaz Undergraduate student, N.I.T Srinagar, India

JM

Joe Metrisin

Mon, Jan 8, 2024 6:49 PM

The geometry engine in ANSYS APDL is over 35 years old. It is very crude
technology by today's standards. I see this all the time and honestly don't
understand why a university student would be using an obsolete tool instead
of the latest and greatest technology. You should be using a real CAD
program, or spaceclaim in Workbench. Do you have a dinosaur for a professor
who is making you do this?

The short story is that ANSYS APDL does not have the capability to create an
accurate representation of the geometry you are trying to feed it. It's
just warning you to that effect.

Joseph T Metrisin
Structures Lead

Florida Turbine Technologies, Inc a KRATOS Company
1701 Military Tr. Suite 110 | Jupiter, FL 33458 USA
+1 (561) 427-6346 Office | +1 (772) 834-4156 Mobile
Joe.Metrisin@kratosdefense.com

We are hiring; Join the FTT Team in Jupiter, Florida
Visit our website: https://kratosdefense.com

Confidentiality Note:
The information contained in this transmission and any attachments are
proprietary and may be privileged, intended only for the use of the
individual or entity named above. If the reader of this message is not the
intended recipient, you are hereby notified that any dissemination,
distribution, or copying of this communication is strictly prohibited. If
you received this communication in error, please delete the message and
immediately notify the sender via the contact information listed above.

-----Original Message-----
From: arsalaan_2020bciv010@nitsri.ac.in arsalaan_2020bciv010@nitsri.ac.in
Sent: Monday, January 8, 2024 1:25 PM
To: xansys-temp@list.xansys.org
Subject: [External] - [Xansys] Warning while creating an area between
bspline and lines

CAUTION: This email originated from outside of the organization. Do not
click links or open attachments unless you recognize the sender and know the
content is safe.

Dear XANSYS community,

I am an undergraduate student in the final year of my program, and I am
currently working on a project that involves using ANSYS APDL. I have
created an area using bsplines and lines utilizing the area command.
However, I received a warning indicating that the lines do not lie on common
coordinate value in the currently active coordinate system, and a Coons
patch is being fitted between them. I would appreciate it if you could
provide more information or guidance on how to resolve this issue.
Additionally, I am curious to learn more about the concept of Coons patch in
the context of ANSYS APDL. Any insights or documentation you can share on
this matter would be highly beneficial for my project. For reference, I have
attached a snippet of the warning message to this email.

I would greatly appreciate any guidance, best practices, or recommended
techniques that could help me achieve this objective more efficiently.

Thank you,

Arsalaan Reyaz

Undergraduate student, N.I.T Srinagar, India

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

The geometry engine in ANSYS APDL is over 35 years old. It is very crude technology by today's standards. I see this all the time and honestly don't understand why a university student would be using an obsolete tool instead of the latest and greatest technology. You should be using a real CAD program, or spaceclaim in Workbench. Do you have a dinosaur for a professor who is making you do this? The short story is that ANSYS APDL does not have the capability to create an accurate representation of the geometry you are trying to feed it. It's just warning you to that effect. Joseph T Metrisin Structures Lead Florida Turbine Technologies, Inc a KRATOS Company 1701 Military Tr. Suite 110 | Jupiter, FL 33458 USA +1 (561) 427-6346 Office | +1 (772) 834-4156 Mobile Joe.Metrisin@kratosdefense.com We are hiring; Join the FTT Team in Jupiter, Florida Visit our website: https://kratosdefense.com Confidentiality Note: The information contained in this transmission and any attachments are proprietary and may be privileged, intended only for the use of the individual or entity named above. If the reader of this message is not the intended recipient, you are hereby notified that any dissemination, distribution, or copying of this communication is strictly prohibited. If you received this communication in error, please delete the message and immediately notify the sender via the contact information listed above. -----Original Message----- From: arsalaan_2020bciv010@nitsri.ac.in <arsalaan_2020bciv010@nitsri.ac.in> Sent: Monday, January 8, 2024 1:25 PM To: xansys-temp@list.xansys.org Subject: [External] - [Xansys] Warning while creating an area between bspline and lines CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe. Dear XANSYS community, I am an undergraduate student in the final year of my program, and I am currently working on a project that involves using ANSYS APDL. I have created an area using bsplines and lines utilizing the area command. However, I received a warning indicating that the lines do not lie on common coordinate value in the currently active coordinate system, and a Coons patch is being fitted between them. I would appreciate it if you could provide more information or guidance on how to resolve this issue. Additionally, I am curious to learn more about the concept of Coons patch in the context of ANSYS APDL. Any insights or documentation you can share on this matter would be highly beneficial for my project. For reference, I have attached a snippet of the warning message to this email. I would greatly appreciate any guidance, best practices, or recommended techniques that could help me achieve this objective more efficiently. Thank you, Arsalaan Reyaz Undergraduate student, N.I.T Srinagar, India _______________________________________________ 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

GK

Gallagher, Keith (GE Aerospace, US)

Mon, Jan 8, 2024 8:50 PM

It's been quite some time since posting on this forum. Hoping others have had some experience with an issue that we are having.

We are currently doing this particular work in Workbench 2022 R2. It involves meshing sub-models with relatively thin walls and complex geometry. Aggressive shape checking is turned on.

Workbench is able to generate a mesh, and the more refined regions of the sub-model generate an acceptable, high quality mesh.

The problem occurs when trying to get a reasonable mesh on the rest of the model. Element size in these regions is 40-50 mil for a part with a 20 mil wall. Workbench is generating elements with negative jacobians in these cases. The model will not solve, even with the workbench default of shape checking being turned off.
The mesher also seems to iterate for a very long time, probably trying to eliminate the bad elements, but eventually accepts the mesh.

It seems wholly unacceptable that workbench identifies this as a good mesh, when in fact it will not successfully solve.

Manually going in with some local refinements eventually eliminates the bad elements, but the resulting process is iterative and extremely time consuming.

Simply making the whole model very refined is not an option due to the resulting mesh size. So I am looking to figure out what might be causing the problem and if it can be eliminated.

Anyone have similar experience or related information to share?

Thanks,
Keith Gallagher
GE Aerospace

It's been quite some time since posting on this forum. Hoping others have had some experience with an issue that we are having. We are currently doing this particular work in Workbench 2022 R2. It involves meshing sub-models with relatively thin walls and complex geometry. Aggressive shape checking is turned on. Workbench is able to generate a mesh, and the more refined regions of the sub-model generate an acceptable, high quality mesh. The problem occurs when trying to get a reasonable mesh on the rest of the model. Element size in these regions is 40-50 mil for a part with a 20 mil wall. Workbench is generating elements with negative jacobians in these cases. The model will not solve, even with the workbench default of shape checking being turned off. The mesher also seems to iterate for a very long time, probably trying to eliminate the bad elements, but eventually accepts the mesh. It seems wholly unacceptable that workbench identifies this as a good mesh, when in fact it will not successfully solve. Manually going in with some local refinements eventually eliminates the bad elements, but the resulting process is iterative and extremely time consuming. Simply making the whole model very refined is not an option due to the resulting mesh size. So I am looking to figure out what might be causing the problem and if it can be eliminated. Anyone have similar experience or related information to share? Thanks, Keith Gallagher GE Aerospace

NH

Nelson Ho

Mon, Jan 8, 2024 9:00 PM

Hi Keith,

For thin walls you might be getting crazy distortions especially with
stress stiffening on.
Have you tried shell modeling what is considered non refined since I am
assuming you only need that for stiffness considerations.

With shells you’ll only have to worry about wastage and aspect ratios.
Jacobians would be inside out elements or hexes looking like triangles.
Also, it slims your model down from 10node tets to 4 node shells if you are
using first order hexes.

Thanks,
Nelson

On Mon, Jan 8, 2024 at 12:50 PM Gallagher, Keith (GE Aerospace, US) <
Keith.Gallagher@ge.com> wrote:

It's been quite some time since posting on this forum. Hoping others have
had some experience with an issue that we are having.

We are currently doing this particular work in Workbench 2022 R2. It
involves meshing sub-models with relatively thin walls and complex
geometry. Aggressive shape checking is turned on.

Workbench is able to generate a mesh, and the more refined regions of the
sub-model generate an acceptable, high quality mesh.

The problem occurs when trying to get a reasonable mesh on the rest of the
model. Element size in these regions is 40-50 mil for a part with a 20 mil
wall. Workbench is generating elements with negative jacobians in these
cases. The model will not solve, even with the workbench default of shape
checking being turned off.
The mesher also seems to iterate for a very long time, probably trying to
eliminate the bad elements, but eventually accepts the mesh.

It seems wholly unacceptable that workbench identifies this as a good
mesh, when in fact it will not successfully solve.

Manually going in with some local refinements eventually eliminates the
bad elements, but the resulting process is iterative and extremely time
consuming.

Simply making the whole model very refined is not an option due to the
resulting mesh size. So I am looking to figure out what might be causing
the problem and if it can be eliminated.

Anyone have similar experience or related information to share?

Thanks,
Keith Gallagher
GE Aerospace

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

Hi Keith, For thin walls you might be getting crazy distortions especially with stress stiffening on. Have you tried shell modeling what is considered non refined since I am assuming you only need that for stiffness considerations. With shells you’ll only have to worry about wastage and aspect ratios. Jacobians would be inside out elements or hexes looking like triangles. Also, it slims your model down from 10node tets to 4 node shells if you are using first order hexes. Thanks, Nelson On Mon, Jan 8, 2024 at 12:50 PM Gallagher, Keith (GE Aerospace, US) < Keith.Gallagher@ge.com> wrote: > It's been quite some time since posting on this forum. Hoping others have > had some experience with an issue that we are having. > > We are currently doing this particular work in Workbench 2022 R2. It > involves meshing sub-models with relatively thin walls and complex > geometry. Aggressive shape checking is turned on. > > Workbench is able to generate a mesh, and the more refined regions of the > sub-model generate an acceptable, high quality mesh. > > The problem occurs when trying to get a reasonable mesh on the rest of the > model. Element size in these regions is 40-50 mil for a part with a 20 mil > wall. Workbench is generating elements with negative jacobians in these > cases. The model will not solve, even with the workbench default of shape > checking being turned off. > The mesher also seems to iterate for a very long time, probably trying to > eliminate the bad elements, but eventually accepts the mesh. > > It seems wholly unacceptable that workbench identifies this as a good > mesh, when in fact it will not successfully solve. > > Manually going in with some local refinements eventually eliminates the > bad elements, but the resulting process is iterative and extremely time > consuming. > > Simply making the whole model very refined is not an option due to the > resulting mesh size. So I am looking to figure out what might be causing > the problem and if it can be eliminated. > > > Anyone have similar experience or related information to share? > > > Thanks, > Keith Gallagher > GE Aerospace > _______________________________________________ > 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 >

GK

Gallagher, Keith (GE Aerospace, US)

Mon, Jan 8, 2024 9:08 PM

Distortions are not the issue. Workbench is generating a bad mesh. It will not solve at all, just errors out right away.

Shells are not an option, unfortunately. These are intended to be detailed sub-models for local stress.

Keith Gallagher
GE Aerospace

-----Original Message-----
From: Nelson Ho nelsonho567@gmail.com
Sent: Monday, January 8, 2024 4:01 PM
To: XANSYS Mailing List Home xansys-temp@list.xansys.org
Subject: EXT: [Xansys] Re: Jacobian errors on tet elements in Workbench

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 Keith,

For thin walls you might be getting crazy distortions especially with stress stiffening on.
Have you tried shell modeling what is considered non refined since I am assuming you only need that for stiffness considerations.

With shells you’ll only have to worry about wastage and aspect ratios.
Jacobians would be inside out elements or hexes looking like triangles.
Also, it slims your model down from 10node tets to 4 node shells if you are using first order hexes.

Thanks,
Nelson

On Mon, Jan 8, 2024 at 12:50 PM Gallagher, Keith (GE Aerospace, US) < Keith.Gallagher@ge.com> wrote:

It's been quite some time since posting on this forum. Hoping others
have had some experience with an issue that we are having.

We are currently doing this particular work in Workbench 2022 R2. It
involves meshing sub-models with relatively thin walls and complex
geometry. Aggressive shape checking is turned on.

Workbench is able to generate a mesh, and the more refined regions of
the sub-model generate an acceptable, high quality mesh.

The problem occurs when trying to get a reasonable mesh on the rest of
the model. Element size in these regions is 40-50 mil for a part with
a 20 mil wall. Workbench is generating elements with negative
jacobians in these cases. The model will not solve, even with the
workbench default of shape checking being turned off.
The mesher also seems to iterate for a very long time, probably trying
to eliminate the bad elements, but eventually accepts the mesh.

It seems wholly unacceptable that workbench identifies this as a good
mesh, when in fact it will not successfully solve.

Manually going in with some local refinements eventually eliminates
the bad elements, but the resulting process is iterative and extremely
time consuming.

Simply making the whole model very refined is not an option due to the
resulting mesh size. So I am looking to figure out what might be
causing the problem and if it can be eliminated.

Anyone have similar experience or related information to share?

Thanks,
Keith Gallagher
GE Aerospace

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

Distortions are not the issue. Workbench is generating a bad mesh. It will not solve at all, just errors out right away. Shells are not an option, unfortunately. These are intended to be detailed sub-models for local stress. Keith Gallagher GE Aerospace -----Original Message----- From: Nelson Ho <nelsonho567@gmail.com> Sent: Monday, January 8, 2024 4:01 PM To: XANSYS Mailing List Home <xansys-temp@list.xansys.org> Subject: EXT: [Xansys] Re: Jacobian errors on tet elements in Workbench 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 Keith, For thin walls you might be getting crazy distortions especially with stress stiffening on. Have you tried shell modeling what is considered non refined since I am assuming you only need that for stiffness considerations. With shells you’ll only have to worry about wastage and aspect ratios. Jacobians would be inside out elements or hexes looking like triangles. Also, it slims your model down from 10node tets to 4 node shells if you are using first order hexes. Thanks, Nelson On Mon, Jan 8, 2024 at 12:50 PM Gallagher, Keith (GE Aerospace, US) < Keith.Gallagher@ge.com> wrote: > It's been quite some time since posting on this forum. Hoping others > have had some experience with an issue that we are having. > > We are currently doing this particular work in Workbench 2022 R2. It > involves meshing sub-models with relatively thin walls and complex > geometry. Aggressive shape checking is turned on. > > Workbench is able to generate a mesh, and the more refined regions of > the sub-model generate an acceptable, high quality mesh. > > The problem occurs when trying to get a reasonable mesh on the rest of > the model. Element size in these regions is 40-50 mil for a part with > a 20 mil wall. Workbench is generating elements with negative > jacobians in these cases. The model will not solve, even with the > workbench default of shape checking being turned off. > The mesher also seems to iterate for a very long time, probably trying > to eliminate the bad elements, but eventually accepts the mesh. > > It seems wholly unacceptable that workbench identifies this as a good > mesh, when in fact it will not successfully solve. > > Manually going in with some local refinements eventually eliminates > the bad elements, but the resulting process is iterative and extremely > time consuming. > > Simply making the whole model very refined is not an option due to the > resulting mesh size. So I am looking to figure out what might be > causing the problem and if it can be eliminated. > > > Anyone have similar experience or related information to share? > > > Thanks, > Keith Gallagher > GE Aerospace > _______________________________________________ > 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

NH

Nelson Ho

Mon, Jan 8, 2024 9:17 PM

Apply nonlinear mechanical settings
Curvature on instead of adaptive.
Set min sizing to something like 0.1”. Can iterate lower or higher based on
what is meshed.

Also, mid surface the plate and use that as a cutting surface to make the
part a two body flow through. That will force two elements through and face
sizing will be the only parameter you need to consider.

On Mon, Jan 8, 2024 at 1:09 PM Gallagher, Keith (GE Aerospace, US) <
Keith.Gallagher@ge.com> wrote:

Distortions are not the issue. Workbench is generating a bad mesh. It
will not solve at all, just errors out right away.

Shells are not an option, unfortunately. These are intended to be
detailed sub-models for local stress.

Keith Gallagher
GE Aerospace

-----Original Message-----
From: Nelson Ho nelsonho567@gmail.com
Sent: Monday, January 8, 2024 4:01 PM
To: XANSYS Mailing List Home xansys-temp@list.xansys.org
Subject: EXT: [Xansys] Re: Jacobian errors on tet elements in Workbench

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 Keith,

For thin walls you might be getting crazy distortions especially with
stress stiffening on.
Have you tried shell modeling what is considered non refined since I am
assuming you only need that for stiffness considerations.

With shells you’ll only have to worry about wastage and aspect ratios.
Jacobians would be inside out elements or hexes looking like triangles.
Also, it slims your model down from 10node tets to 4 node shells if you
are using first order hexes.