transient analysis does not converge for your model

Ali S.
Ali S. Altair Community Member
edited August 2023 in Community Q&A

Hello everybody,

i have a problem during the simulation. when i translate it to english he text is something like: transient analysis does not converge for your model

I tried to solve this problem by increasing the frequency in the property window of the analysis. because this was the suggestion from inspire.  I go up to 1000Hz but this did not help. The suggestions in the help center also did no help.

what does this failure mean? how can i solve it?

Can somebody help me?

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Answers

  • Scott Ziemba_21777
    Scott Ziemba_21777
    Altair Employee
    edited August 2023

    Hi Ali,

    It would be helpful if you provided more detail about the model.  Do you have motion contacts defined in the model? Do you have friction modeled on the contacts or on joints?  Is there an input? (disp, speed, accel?).... One or a combination of these features in your model can contribute to faults during the solve.  What is the model doing at the point of failure? Is there any visual indication of a conflict or binding of joint, etc.?

    The following is taken directly from the Inspire Help if you selected Help (or pressed F1) when the error appears:

    Transient Analysis Is Not Converging for Your Model

    Condition

    Integrator convergence problems detected during transient analysis of this model.

    Remedy

    • Try slowing down the rate of profile functions used on motors or actuators in your model by changing time values or magnitudes.
    • Try switching the Model Units from MKS to something else via File > Preferences > Inspire > Model Units.
    • Try increasing the Output rate in the Run Motion Analysis settings so you can better see what is happening right before the error occurs.
    • Enable (or disable) the controller for the motor or actuator to see whether or not it has an effect.
    • Try to simplify what is happening in your model by locking motors or actuators, or using rigid groups or grounding to temporarily prevent some parts of the model from moving.
    • Try changing the controller parameters (e.g. PID Gains) for the motor or actuator.
    • Try starting from an equilibrium position when running transient analysis.
    • Joint behavior may be too stiff, or not stiff enough. Try changing the magnitude of Motion Rates for flexible joint behavior.
    • Change the Solver settings on the Run Motion Analysis window (e.g. Maximum step size, Integrator tolerance).

     

    If, in the end, you are still having trouble with converging, please create a support ticket and send the model to Altair so the support team can help take a closer look.

    Regards,

    Scott Z

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