Hi,

I gave up on the previous issue.

Here's a new one.  I take a 2D model with plane42's and convert them to 182's and I get this error....

*** ERROR ***                          CP =      9.531  TIME= 08:00:40
The length of kinematic record does not match the saved length
specifications.  Please send the data leading to this operation to
your technical support provider, as this will allow ANSYS, Inc to
improve the program.

Any idea what that means?

Thanks,

Dan Bohlen
Senior Engineer, Stress Analysis
Compliance Ambassador and Section Focal
GE Aerospace
1 Neumann Way
Evendale, OH  45215  USA

From: Chandra Sekaran chandra.sekaran@ansys.com
Sent: Tuesday, December 2, 2025 11:35 AM
To: Bohlen, Dan (GE Aerospace, US) dan.bohlen@geaerospace.com
Subject: SR 561574 modal analysis - pstres,on vs perturbation

You don't often get email from chandra.sekaran@ansys.commailto:chandra.sekaran@ansys.com. Learn why this is importanthttps://aka.ms/LearnAboutSenderIdentification
Hello Dan,

My name is Chandra Sekaran. I will help you with this support case. FYI I am a US citizen based out of Pittsburgh PA. I am trained at Ansys to deal with export controlled information.

I get different natural frequencies between "old school" modal and perturbation . Running a model back to back and getting 2X higher freq using antype modal-->solve versus perturbation method.

Can you confirm that by "old school" you mean a static run with pstres,on (small deflection linear) followed by modal with pstres,on?  Or is it something else?  Is the linear perturbation case using nlgeom,on?

Could we meet on secure Teams call to bring myself up to speed?

Thank you and best regards,

Chandra

Just spitballing here, but the default for Plane42 is to use bubble functions whereas the 182 elements use selective reduced integration to try and accomplish the same thing. Perhaps the kinematic length refers to the number of dof used to approximate displacements, which would be different for the two elements. Obviously if the code allows you to convert this should be taken care of automatically but...

Peter

From: Bohlen, Dan (GE Aerospace, US) via Xansys xansys-temp@list.xansys.org
Sent: Friday, December 5, 2025 7:03 AM
To: Chandra Sekaran
Cc: XANSYS Mailing List Home; Bohlen, Dan (GE Aerospace, US)
Subject: [Xansys] Re: SR 561574 modal analysis - pstres,on vs perturbation

Hi, I gave up on the previous issue. Here's a new one. I take a 2D model with plane42's and convert them to 182's and I get this error. . . . *** ERROR *** CP = 9. 531 TIME= 08: 00: 40 The length of kinematic record does not match the saved length
ZjQcmQRYFpfptBannerStart
External Email

ZjQcmQRYFpfptBannerEnd

Hi,

I gave up on the previous issue.

Here's a new one.  I take a 2D model with plane42's and convert them to 182's and I get this error....

*** ERROR ***                          CP =      9.531  TIME= 08:00:40
The length of kinematic record does not match the saved length
specifications.  Please send the data leading to this operation to
your technical support provider, as this will allow ANSYS, Inc to
improve the program.

Any idea what that means?

Thanks,

Dan Bohlen
Senior Engineer, Stress Analysis
Compliance Ambassador and Section Focal
GE Aerospace
1 Neumann Way
Evendale, OH  45215  USA

From: Chandra Sekaran chandra.sekaran@ansys.com
Sent: Tuesday, December 2, 2025 11:35 AM
To: Bohlen, Dan (GE Aerospace, US) dan.bohlen@geaerospace.com
Subject: SR 561574 modal analysis - pstres,on vs perturbation

You don't often get email from chandra.sekaran@ansys.commailto:chandra.sekaran@ansys.com. Learn why this is importanthttps://urldefense.com/v3/__https://aka.ms/LearnAboutSenderIdentification__;!!GNU8KkXDZlD12Q!5onK0TBat0yki2bEdI8ImRlUEBNjAh0wn-i4t8ZSQg-t97xfu8SlZz4cmYlTuKhP5cfp2WgczUQA78j6MPp4jLXYceo$[aka[.]ms]
Hello Dan,

My name is Chandra Sekaran. I will help you with this support case. FYI I am a US citizen based out of Pittsburgh PA. I am trained at Ansys to deal with export controlled information.

I get different natural frequencies between "old school" modal and perturbation . Running a model back to back and getting 2X higher freq using antype modal-->solve versus perturbation method.

Can you confirm that by "old school" you mean a static run with pstres,on (small deflection linear) followed by modal with pstres,on?  Or is it something else?  Is the linear perturbation case using nlgeom,on?

Could we meet on secure Teams call to bring myself up to speed?

Thank you and best regards,

Chandra

Xansys mailing list -- xansys-temp@list.xansys.org
To unsubscribe send an email to xansys-temp-leave@list.xansys.org
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Got an answer...makes sense.....why the error message doesn't give the user these clues....

Do you have any other element types present in the model? PLANE42 and PLANE182 do use different kinematic record lengths to store information. However, this message typically appears only if the element type is changed between load steps or in a restart analysis.
I have seen a similar error when a user converted SOLID45 to SOLID185, but still had some legacy SOLID5 (piezoelectric) elements in the model. Once those were also updated to SOLID225, the error disappeared. You may be running into something along those lines.

-----Original Message-----
From: Bohlen, Dan (GE Aerospace, US) via Xansys xansys-temp@list.xansys.org
Sent: Friday, December 5, 2025 8:03 AM
To: Chandra Sekaran chandra.sekaran@ansys.com
Cc: XANSYS Mailing List Home xansys-temp@list.xansys.org; Bohlen, Dan (GE Aerospace, US) dan.bohlen@geaerospace.com
Subject: EXT: [Xansys] Re: SR 561574 modal analysis - pstres,on vs perturbation

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Hi,

I gave up on the previous issue.

Here's a new one.  I take a 2D model with plane42's and convert them to 182's and I get this error....

*** ERROR ***                          CP =      9.531  TIME= 08:00:40
The length of kinematic record does not match the saved length specifications.  Please send the data leading to this operation to your technical support provider, as this will allow ANSYS, Inc to improve the program.

Any idea what that means?

Thanks,

Dan Bohlen
Senior Engineer, Stress Analysis
Compliance Ambassador and Section Focal
GE Aerospace
1 Neumann Way
Evendale, OH  45215  USA

From: Chandra Sekaran chandra.sekaran@ansys.com
Sent: Tuesday, December 2, 2025 11:35 AM
To: Bohlen, Dan (GE Aerospace, US) dan.bohlen@geaerospace.com
Subject: SR 561574 modal analysis - pstres,on vs perturbation

You don't often get email from chandra.sekaran@ansys.commailto:chandra.sekaran@ansys.com. Learn why this is importanthttps://aka.ms/LearnAboutSenderIdentification
Hello Dan,

My name is Chandra Sekaran. I will help you with this support case. FYI I am a US citizen based out of Pittsburgh PA. I am trained at Ansys to deal with export controlled information.

I get different natural frequencies between "old school" modal and perturbation . Running a model back to back and getting 2X higher freq using antype modal-->solve versus perturbation method.

Can you confirm that by "old school" you mean a static run with pstres,on (small deflection linear) followed by modal with pstres,on?  Or is it something else?  Is the linear perturbation case using nlgeom,on?

Could we meet on secure Teams call to bring myself up to speed?

Thank you and best regards,

Chandra

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

Our good friend, ChatGPT, gave me this when I asked him about the
difference between SOLVE and PSOLVE,Eigen commands when used in ANSYS Modal
Analysis. I hope it helps:

In ANSYS (APDL / Classic) modal analysis, these two commands serve
different purposes and act at different levels of the solution process:

SOLVE

What it does

SOLVE is the high-level command that tells ANSYS to:

1. Assemble the global matrices
   2. Call the appropriate solver
   3. Compute the requested results (here: eigenvalues and mode shapes)
   4. Store the results in the results file (.rst)

In modal analysis

When you issue:

ANTYPE,MODAL

MODOPT,LANB,10

SOLVE

ANSYS internally:

• Forms K (stiffness) and M (mass)
• Solves the eigenvalue problem
  ( \mathbf{K} - \omega^2 \mathbf{M} ) \boldsymbol{\phi} = 0
• Writes natural frequencies and mode shapes

Key point

SOLVE is the standard and recommended command for modal analysis.

PSOLVE,EIGEN

What it does

• PSOLVE is a lower-level / processor-level solver command
• PSOLVE,EIGEN explicitly calls the eigensolver only
• It bypasses much of the automated solution control done by SOLVE

Typical intent

• Used internally by ANSYS
• Used by advanced users for:
• Debugging
  • Custom solution sequences
  • Research-level control of solver stages

Limitations

• Does not perform the full solution sequence automatically
• Requires matrices and options to already be correctly set up
• Easier to misuse
• Not documented for routine user workflows

Key point

PSOLVE,EIGEN is not intended for normal modal analysis runs.

3. Practical Comparison

Aspect

SOLVE

PSOLVE,EIGEN

User level

Standard user

Advanced / internal

Automation

Full

Minimal

Recommended

✅ Yes

❌ No (unless expert)

Result handling

Automatic

Manual / limited

Typical usage

Modal, static, harmonic

Solver research / debugging

4. Which should

you

use?

For engineering modal analysis (including electronics packaging, solder
joints, etc.):

✅ Always use

SOLVE

❌ Do not use

PSOLVE,EIGEN

unless you fully understand ANSYS solver internals.

5. One-sentence takeaway

SOLVE is the correct, complete command for modal analysis, while
PSOLVE,EIGEN is a low-level eigensolver call mainly intended for internal
or expert use.

In ANSYS (APDL / Classic) modal analysis, these two commands serve
different purposes and act at different levels of the solution process:

SOLVE

What it does

• SOLVE is the high-level command that tells ANSYS to:
• 1. Assemble the global matrices
  2. Call the appropriate solver
  3. Compute the requested results (here: eigenvalues and mode shapes)
  4. Store the results in the results file (.rst)

In modal analysis

When you issue:

ANTYPE,MODAL

MODOPT,LANB,10

SOLVE

ANSYS internally:

• Forms K (stiffness) and M (mass)
• Solves the eigenvalue problem
  ( \mathbf{K} - \omega^2 \mathbf{M} ) \boldsymbol{\phi} = 0
• Writes natural frequencies and mode shapes

Key point

SOLVE is the standard and recommended command for modal analysis.

PSOLVE,EIGEN

What it does

• PSOLVE is a lower-level / processor-level solver command
• PSOLVE,EIGEN explicitly calls the eigensolver only
• It bypasses much of the automated solution control done by SOLVE

Typical intent

• Used internally by ANSYS
• Used by advanced users for:
• • Debugging
  • Custom solution sequences
  • Research-level control of solver stages

Limitations

• Does not perform the full solution sequence automatically
• Requires matrices and options to already be correctly set up
• Easier to misuse
• Not documented for routine user workflows

Key point

PSOLVE,EIGEN is not intended for normal modal analysis runs.

3. Practical Comparison

Aspect

SOLVE

PSOLVE,EIGEN

User level

Standard user

Advanced / internal

Automation

Full

Minimal

Recommended

✅ Yes

❌ No (unless expert)

Result handling

Automatic

Manual / limited

Typical usage

Modal, static, harmonic

Solver research / debugging

4. Which should

you

use?

For engineering modal analysis (including electronics packaging, solder
joints, etc.):

✅ Always use

SOLVE

❌ Do not use

PSOLVE,EIGEN

unless you fully understand ANSYS solver internals.

5. One-sentence takeaway

SOLVE is the correct, complete command for modal analysis, while
PSOLVE,EIGEN is a low-level eigensolver call mainly intended for internal
or expert use.