Model not running with no load collectors.

Altair Forum User
Altair Forum User
Altair Employee
edited October 2020 in Community Q&A

Hi Experts,

 

I'm conducting some simulation runs on my model with advanced mass scaling and the results are not stable so in order of further investigation I have intentionally removed all the load collectors present in the model just to verify the scenario of mass scaling when there is absolutely no movement in the model and also no residual forces caused due to BCS or any of the pre loaded elements. Strangely the model is running and generating no output... I am really surprised by the phenomenon. However I tried the same scenario i.e, model with no load collectors and using constant time step /DT/NODA/CST on the model... and the model is responding I mean I could successfully run the model with no errors. My question is why does the model leading to an error when AMS is employed on it ?? Even though there is no dynamic activity assigned to the model.. 

 

Thanks for your support in advance..

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited July 2017

    Hi Raghav,

    As you know, time step is dependent on the length of element and speed of sound, which is again related to both material modulus and density that controls speed of sound. So, as you applied /DT/NODA the run was completed easily with time step control. 

    There can be various reasons that can cause /AMS to diverge.If the target time step provided is much higher it can lead to such a situation.

    I just tried in a simple model, no loads and bc's, with these three cases (no time step control, with /DT/NODA and /AMS) and all the three ran successfully. 

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