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Composite failure analysis problem (VUSDFLD)

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loyal979

Mechanical
Nov 6, 2018
47
Hi all,

I am simulating a tensile loading in ABAQUS/explicit for a notched composite plate. I have implemented my failure initiation in a user subroutine VUSDFLD. My failure equation is as follow: f = (S11/Xt)^2 where S11 is the stress from abaqus and Xt is the laminate tensile strength. The problem that I get is that the plate fails and my failure indicator has a value of 1 (for example: I check one element )which means that there is failure; however, when I look at the stress S11 of one element, where it should be failing, the stress is below the ultimate strength. Thus, I am just wondering why is it failing if the stress did not reach the ultimate strength? I was monitoring one element in each increment and the stress is increasing and that what should happen, but once failure happen the stress get reported by ABAQUS is not equal to or greater than the ultimate strength ( below the ultimate strength).
I have attached screen shot of my failure evaluation from my subroutine. Please share your thoughts and feedback on this issue. Thank you in advance!!
Capture_tx2cqs.jpg
 
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