Assessment of inverse procedures for the identification of hyperelastic material parameters

Abstract

This work aimed to implement and compare two competitive procedures for the identification of hyperelastic material parameters. Formerly, experimental tests have been conducted on fluorosilicone rubber specimens in equal-biaxial tension; the cruciform shaped-specimens underwent heterogeneous large strain distributions, which were captured by Digital Image Correlation technique; while load cells grabbed the force signals. The experimental data have been used in two different inverse techniques for material parameters estimation: the first method was based on "classic" FE model updating, which uses only the global quantities measured during the experiments (i.e. forces and boundary displacements) to define the error function to be minimized; the second method was still based on FE model updating, but experimentally determined strain fields was compared with the numerical ones in order to define a more adequate cost function; third technique was based on the Virtual Fields Method, which naturally takes into account the real strain distributions and permits to overcome the experimental difficulties represented by non-symmetry of the test/specimen, non-uniform boundary conditions, friction. The results of the three procedures are showed and compared in terms of accuracy, transferability, computational efficiency and practicability.