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An Issue on a quite simple model while doing Time Dependent Analysis by using LMS and MBD

Posted 21 août 2019, 11:07 UTC−4 Version 5.3a 3 Replies

Leon Chan
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Hello,

This is a very simple model with only one block actually. But I have been struggling on this for quite a while.

When I disabled the Damper C1, it can pass the test. However, with the damper actived it showed an Error:

  • Feature: Time-Dependent Solver 1 (sol1/t1) Repeated error test failures. May have reached a singularity. Time : 0 Last time step is not converged.

Can anyone help me on this? The two models with my idea is as attached. Thank you in advance.

3 Replies Last Post 23 août 2019, 07:40 UTC−4
Pawan Soami COMSOL Employee

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Posted: 5 years ago 22 août 2019, 02:29 UTC−4

Dear Leon,

Try using Velocity node instead of Displacement node to prescribe the motion when you have a damper in parallel to a spring. This should resolve the problem.

Best regards,
Pawan Soami

Dear Leon, Try using Velocity node instead of Displacement node to prescribe the motion when you have a damper in parallel to a spring. This should resolve the problem. Best regards, Pawan Soami
Leon Chan
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Posted: 5 years ago 22 août 2019, 06:51 UTC−4

Dear Pawan,

Thank your response and the support!

Best wishes, Leon

Dear Pawan, Thank your response and the support! Best wishes, Leon
Leon Chan
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Posted: 5 years ago 23 août 2019, 07:40 UTC−4

Dear Leon,

Try using Velocity node instead of Displacement node to prescribe the motion when you have a damper in parallel to a spring. This should resolve the problem.

Best regards,
Pawan Soami

With the Velocity node instead of Displacement node, it works in the ‘Time Dependant Study’, but it does not work for the 'Eigenfrequency Study':

  • Feature: Eigenvalue Solver 1 (sol2/e1) Singular matrix.
  • Detail: There are 1 void equations (empty rows in matrix) for the variable comp1.lms.vel1_p1_u. at coordinates: (0,0,0), ...
>Dear Leon, > >Try using Velocity node instead of Displacement node to prescribe the motion when you have a damper in parallel to a spring. This should resolve the problem. > >Best regards, >Pawan Soami With the Velocity node instead of Displacement node, it works in the ‘Time Dependant Study’, but it does not work for the 'Eigenfrequency Study': - Feature: Eigenvalue Solver 1 (sol2/e1) Singular matrix. - Detail: There are 1 void equations (empty rows in matrix) for the variable comp1.lms.vel1_p1_u. at coordinates: (0,0,0), ...

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