How to validate obtained tangent matrix in isotropic linear hardening

[kushwah_dk]

Hi,

I have written a UMAT for isotropic linear hardening model for calculating tangent modulus matrix. Now I want to check that the obtained tangent matrix is correct or not, could you please help me by providing any suitable solved example?

 

[FEA way]

The best way to test UMAT subroutines is to run single-element tests, possibly in comparison with built-in material models available in Abaqus. You can find some examples in the Verification guide in Abaqus documentation.

 

[IceBreakerSours]

I am assuming you have an analytical expression for the tangent stiffness matrix. If not, then you may wish to consider using a symbolic math package for that purpose. Then, under simple BCs, predict what the results ought to be from the analytical expression and compare the prediction with simple numerical tests (single element and patch of elements).

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