CAE-based application for identification and verification of hyperelastic parameters

The main objective of this study is to develop a CAE-based application with a convenient GUI for identification and verification of material parameters for hyperelastic models available in the current release of the FE code ANSYS Mechanical APDL. This Windows application implements a two-step procedure: (1) fitting of experimental stress–strain curves provided by the user; (2) verification of the obtained material parameters by the solution of a modified benchmark problem. The application, which was developed using the Visual Basic.NET language, implements a two-way interaction with ANSYS as a single loop using the APDL script as input and text, graphical and video files as output. With this application, nine isotropic incompressible hyperelastic material models are compared by fitting them to the conventional Treloar’s experimental dataset (1944) for vulcanised rubber. A ranking of hyperelastic models is constructed according to model efficiency, which is estimated using fitting quality criteria. The model ranking is done based upon the complexity of their mathematical formulation and their ability to accurately reproduce the test data. Recent hyperelastic models (Extended Tube and Response Function) are found to be more efficient compared to conventional ones. The verification is done by the comparison of an analytical solution to an FEA result for the benchmark problem of a rubber cylinder under compression proposed by Lindley (1967). In the application, the classical formulation of the benchmark is improved mathematically to become valid for larger deformations. The wide applicability of the proposed two-step approach is confirmed using stress–strains curves for seven different formulations of natural rubber and seven different grades of synthetic rubber.