UMAT and VUMAT subroutines in Abaqus

UMAT and VUMAT subroutines in Abaqus, Define complex or unusual and novel material models that are not available by default in ABAQUS.

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).

In fact, this subroutine is used to define complex or unusual and novel material models that are not available by default in ABAQUS.

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.

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.