UMAT-to-VUMAT Conversion Code for Abaqus

This repository provides a UMAT-to-VUMAT conversion code that assists in migrating user material subroutines from Abaqus/Standard (UMAT) to Abaqus/Explicit (VUMAT). The code automates key interface and data-structure translations (e.g., stress/strain component ordering and state-variable handling) and generates a VUMAT-ready template. The conversion workflow is intended to reduce manual editing effort and common implementation errors when transferring constitutive models between implicit and explicit solvers.
The package includes the conversion scripts, parallel Fortran 90/95 (free-form) and Fortran 77 (fixed-form) source files, and brief usage notes.
The release is distributed under GNU GPL v2.0; portions of this release are derived from upstream GPLv2 code by Bienen et al. (2014); the original source is available at https://soilmodels.com/download/vumat_umatinterface-zip/
Users should verify the converted VUMAT against element-level benchmarks and problem-specific tests before production analyses.