Hi! I am trying to verify Abaqus VUMAT with simple examples so I wrote a VUMAT for orthotropic material and compare the result with Abaqus built-in material model (Elastic -> Engineering constants). The material constants are given in 1.png and 2.png. All other settings from part to mesh is identical. The stress distribution of build-in material model is in 3.png and the stress distribution of VUMAT is in 4.png. The discrepancy is not ignorable. The VUMAT code is also attached in this thread: https://www.researchgate.net/post/Why_VUMAT_for_elastic_material_gives_different_results_from_the_one_given_by_Abaqus_built-in_material_model

Is there anything that I miss in my code? Thanks.

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