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Assign fiber orientation in UMAT

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Joined: 7 years ago

Dear all,

I am working on reproducing the Holzapfel-Gasser-Ogden form of fiber-reinforced anisotropic material model, with the UMAT in abaqus.

With a simple proof-of-concept model, I am currently using solution-dependent variables (statev in umat, or depvar in inp file keyword) to record fiber orientations. I initialize them at the 1st increment of the model, based on the coordinates.

However, I wonder where there is a standard way to do it, e.g. access the material orientation defined using *orientation keyword. This would be much scalable than my current quick-and-dirty way of doing it.

Any comments would be appreciated. Thanks!

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Posts: 2
New Member
Joined: 5 years ago


I am also trying to do the same you doing. I wrote a subroutine which works fine without *Orientation turned on. With *Orientation the program dies after few increments. Any suggestion? Is anything I need to include when material direction is defined with respect to local coordinate system?


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