Development of python script to alter the face numbering of C3D8 elements in ABAQUS

Abstract

The finite element method (FEM) is a numerical technique to solve a partial differential equation. The commercially available software package ABAQUS is very popular in academia as well as industries to analyze engineering problems using FEM. Advanced constitutive theories for materials require the implementation of new elements in the software package ABAQUS. In Abaqus, the essential boundary conditions such as displacement or temperature boundary conditions are taken care of by the software, whereas the natural boundary conditions such as force and flux boundary conditions need to be implemented in the user element (UEL) subroutine. For this, purpose, the information the surfaces of a particular element must be available in the element subroutine. It must be mentioned that ABAQUS does not provide the information on surfaces at the element level, therefore it becomes mandatory for the user to number the element surfaces compatible with the implementation of the element subroutine. If a uniform mesh is created within ABAQUS itself, the face numbering is uniform and can be altered as per requirement. However, controlling face numbering is impossible if the mesh is imported from some other tool or has transition elements. Therefore, the node numbers must be altered to make them compatible with the implementation of UEL before running the analysis. In a three-dimensional element, the face numbering can be altered by changing the element connectivity. In this project, a python script is developed to change the face numbering of brick elements before running the simulations in ABAQUS. The algorithm employed in the script is explained with clear illustrations. Three methods have been deployed to select the faces of a part instance for which the face numbering is to be made uniform.