{"id":462007,"date":"2026-07-30T13:42:00","date_gmt":"2026-07-30T13:42:00","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/what-does-the-push-forward-subroutine-do\/"},"modified":"2026-07-30T13:42:00","modified_gmt":"2026-07-30T13:42:00","slug":"what-does-the-push-forward-subroutine-do","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/what-does-the-push-forward-subroutine-do\/","title":{"rendered":"What does the Push Forward Subroutine do?"},"content":{"rendered":"

<p>I am working on implementing a user defined hyperelastic material which needs a push forward operation. I saw the push_forward_2s(), I’m using the scalar version for now, in Manual 1 Appendix A. However, it does not describe in sufficient detail for me to understand what this function does. <\/p><p>Detailed questions:<\/p><\/p>\n

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  1. What stress is this function expecting as input? First Piola-Kirchhoff? Second Piola-Kirchoff? Something else? <\/li>\n
  2. Does it account for the change in volume from the reference to the current configuration with 1\/detF or do I need to handle that outside of this subroutine? <\/li>\n
  3. What stress is the ouptut from this function? I am assuming Cauchy but I would like confirmation.<\/li>\n<\/ol>\n

    <p>I have implemented my own push forward code in the user-defined material to go from the second PK stress to Cauchy stress using the well known equation sig = 1\/detF * F * 2PK * F^T. However, the results do not match. It is also possible I have made a mistake in my code but the push forward is relatively straight-forward. <\/p><p>Thanks in advance.<\/p><\/p>\n","protected":false},"template":"","class_list":["post-462007","topic","type-topic","status-publish","hentry","topic-tag-material-model","topic-tag-user-defined-1","topic-tag-user-defined-function-1"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t