Introduction to UMAT Subroutine (VUMAT)
During the process of solving each problem, ABAQUS uses a specific program to relate the strain to the stress (the material model). So, If we can not use the material model in ABAQUS/CAE, the user should write the subroutine format known to ABAQUS as UMAT subroutine (in standard solver) or VUMAT subroutine (in explicit solver).
Indeed, this tutorial package contains basic principles and concepts along with practical examples to get acquainted with this subroutine. In the other words, the ultimate goal of this tutorial is to give the user the ability to write UMAT subroutine and VUMAT subroutine to define the mechanical behavior of materials and introduce them to the ABAQUS software. See full information about what you are learning in the drop-down menu by clicking here.
You can find a demo of this package on our channel on YouTube.
Moreover, the general description of how to write a subroutine is available in the article titled “Start Writing a Subroutine in Abaqus: Basics and Recommendations “. You may also like this article to begin writing your own UMAT: Start Writing Your First UMAT in Abaqus
Advanced UMAT Subroutine (VUMAT Subroutine)
The advanced UMAT subroutine training package examines complex behaviors such as the dependence of material behavior on temperature and nonlinear behaviors such as plasticity and damage. Firstly, we explain damage in non-metallic materials such as composites and adhesives, which have completely different elastic behavior. To help the user to write subroutines for different materials. You can see the description of each of the workshops as follows.
Workshop 1: Writing advanced UMAT Subroutine for Non-Isothermal Elasticity
When the elastic behavior of material becomes temperature-dependent, the elastic equations for calculating strain and stress will be different. In this workshop, the process of obtaining these temperature-dependent equations is first explained. In the following, the complete equations used in Subroutine are visible and we explain the implementation of the subroutine line by line in Fortran.