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Simple impact simulation do not converge

Altair Forum User

Hi,

I am trying to learn how to realize an impact test with RADIOSS. I folowed this tutorial from Altair University: https://www.youtube.com/watch?v=aDeNhQFvqjE&t=304s

I folowed every steps of this video but my simulation seems not to converge... I stopped it after 30 minutes and here is the last iteration message:

568955877_Error99.9.PNG.4bfdd1db251e989a8a3f0c98c1ccb549.PNG

You can see that after 1715s I had an error of 99.9%, and the remaining time was increasing again and again (so the response couldn't converge)

Before running the test, I had no error in the model checker:

1837989501_Errorcheck.PNG.e3054743cc8060e0fd7f9705a572b0b2.PNG

And here is the picture of mu model:

1531121560_Droptestpic.PNG.67c16f88ea4700a1af2095ae116f3c19.PNG

I attached a file to this post which is the model i use for this simulation.

Thank you very much for the help. Quentin BERMOND

Unable to find an attachment - read this blog

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Altair Forum User

help？

Simon Križnik

Hi,

the shared model had some issues:

unit consistency: input units were defined as kg, m, s in the begin card, but initial velocity and material (steel?) had values more consistent with tonne, mm, s unit system
impactor with 34000 mm/s (122.4 km/h) initial velocity and 450 kg mass has too much initial kinetic energy for the plate to absorb
animation output frequency (ANIM/DT) was too low to capture deformations
contact was modified

The model is able to solve with failure plastic strain (EPS_p_max) defined. Without material fracture the model will fail to solve as the loading is so high the plate will undergo unrealistic deformations causing numerical difficulties.

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Altair Forum User

Thank you very much for the help, I will try to run this simulation during the week with the modifications you suggested. I would never have noticed these errors without you since these values are directly taken from the Altair Tutorial.

Best regards, Quentin