Modeling Functionally Graded Materials in ANSYS APDL

Abstract

Since its first implementation in the mid-eighties of the past century, Functionally Graded Materials (FGM) have been under heavy research in many directions including manufacturing techniques, modeling, and exploring possible applications. Numerous FGM models and analysis methods are continuously appended to the literature. Just like in the rest of the mechanical design field, the Finite Element Method (FEM) has been extensively used in the analysis of FGM, in addition to being a main validation tool for the other proposed methods. ANSYS has been one of the main general-purpose FEM packages that facilitate the use of FEM. However, no single publication is found exploring the modeling of FGM in ANSYS. This work does just that. It explores and compares the various techniques of modeling FGM in ANSYS using Mechanical APDL. The techniques explored here should be applicable in any other FEM package. APDL codes are provided for the various considered cases. Three main techniques of modeling FGM in ANSYS are presented, namely imposing fictive thermal load, stacking elements/layers, and using user-defined fields. Other advanced methods, that require recompiling the executable ANSYS.exe, are briefly mentioned. Various modeling techniques are implemented on a relatively long cuboid FGM part which is assumed under lateral load and supported at its far edge/s. The configuration of cuboid geometry and lateral load is intentionally considered to allow volume-, area-, and line-finite elements to be implemented. One dimensional continuous and discrete properties variation is considered. The presented modeling techniques of FGM are found equivalent in accuracy.