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converting umat into vumat

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Posts: 11
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Joined: 15 years ago


I want to model granular material under cyclic loading and I want to use vumat in abaqus explicit. I have download a umat from [url][/url] and I want to convert it to vumat. can any one help me. because I do not have enough expertise to do this work.

I have attached the umat file and the paper that explains the granular material costitutive behavior.

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Converting UMAT into VUMAT is easy whereas converting VUMAT into UMAT needs relatively higher expertise.

Above is valid on theoretical grounds, resulting from the finite element techniques that exploit the subroutines, i.e. implicit and explicit.
For an explicit code you do not need a tangent, so you can kick DDSDDE out. Depending on your procedure you can even
simplify the return map and replace a closest point projection by a cutting plane. This could be all the story.

However ABAQUS people introduce additional conventional differences in between UMAT and VUMAT.
Some of these are senselessly created differences which has no aim. For instance the order of shear components.
There are some relatively understandable differences like VUMATs utilization of a corotational framework in all cases.

Good luck in your easy trip, since you have selected converting U to V.

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