New paper on PyTorch-t0-FORTRAN UMAT implementation of level set plasticity accepted by Mechanics of Materials

.Our collaborative research with Sandia National Laboratories on pyTorch-UMAT implementation for machine learning models has been accepted by Mechanics of Materials (See preprint [PDF]).
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This paper introduces a publicly available PyTorch-ABAQUS deep-learning framework of a family of plasticity models where the yield surface is implicitly represented by a scalar-valued function. Our goal is to introduce a practical framework that can be deployed for engineering analysis that employs a user-defined material subroutine (UMAT/VUMAT) for ABAQUS, which is written in FORTRAN (see below)




To accomplish this task while leveraging the back-propagation learning algorithm to speed up the neural-network training, we introduce an interface code where the weights and biases of the trained neural networks obtained via the PyTorch library can be automatically converted into a generic FORTRAN code that can be a part of the UMAT/VUMAT algorithm. To enable third-party validation, we purposely make all the data sets, source code used to train the neural-network-based constitutive models, and the trained models available in a public repository. See the link below:

https://github.com/hyoungsuksuh/ABAQUS_NN

A variety of options (see below) of NN architecture has been pre-trained (see below)..

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Benchmark material point simulations and finite element simulations in ABAQUS has been provided in the repository.  Please feel free to modify the codes and we would appreciate that if you can cite this paper if you use it for your own research. 

Note: we are actively developing this repository which may contain bugs. If you encounter a bug, please let us (Hyoung Suk Suh, h.suh@columbia.edu; WaiChing Sun, wsun@columbia.edu) know. Please cite our work if you use it for your own research. We hope that this small tool can encourage and help more researchers from the ABAQUS ecosystem to build their own neural network model. Thank you! 

Reference: 

• H.S. Suh, C. Kweon, B. Lester, S. Kramer, W.C. Sun, A publicly available e PyTorch-ABAQUS UMAT deep-learning framework for level-set plasticity, Mechanics of Materials, in press, 2023.