Hello Scholars!
I'm implementing a user-defined material subroutine in LS Dyna. I intend to build a rate dependent model, so I have to use strain rate as a variable in my model.
I'm currently using UMAT 41 (the scalar version). I tried to use rate=eps(i)/dt1 as the strain rate in the code, but after issuing a print statement for rate, I see NaN for rate value. Can anybody tell me how to use strain rate in a scalar version or do I essentially need to use a vectorized version of the UMATs to use strain rate?
Thanks in advance
What is the value of dt1?
Sometimes, if the value of dt1 nearly 0.0001 secs, the divergent (eps(i)/0 = infinity) occurred, that's why ''not a number (NaN)'' was shown there.
I am also facing similar types of problems.
Hello Atik Sarraz !
dt1 is the current time step size and is a variable calculated by LS Dyna and provided to the subroutine. Maybe it is the problem that you have mentioned.
Not sure if I should move on to vectorized UMATs. I am trying one now anyways.
A bit complex to understand since I'm new to the business
Incremental time steps should set carefully, although i am running a code written for impact cases, but divergence could be occurred if the value could not be checked carefully....divergence also depends of mesh density....btw best of luck
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