ABSTRACT
Covering up several loading conditions with a unique experimental set-up is simpler and allows to observe coupling between different strain states. Two principal types of multiaxial tests exist: biaxial tests with cross-shaped specimens (Rivlin & Saunders 1951, Blatz & Ko 1962, Treloar 1948, Kawabata et al. 1981, Becker 1967), and tension or compression combined with torsion using cylindrical specimens (Rivlin & Saunders 1951, Haupt & Sedlan 2001, Mars & Fatemi 2004, Suphadon et al. 2009). Few contributions have been found about tension/torsion tests, and those existing are mainly related to fatigue studies. In this case, the major requirement of the specimen is to present a stress concentration zone. As regards behavior characterization, the existence of a zone of interest in which the analytical solution for the mechanical problem is known takes precedence. The analytical solution of an infinite cylinder submitted to tension and torsion is known, but the specimen cannot be perfectly cylindrical since an effective interface with the testing machine has to be ensured. A compromise has to be found between
1 INTRODUCTION
Due to the weight of the engine and various perturbations from the road, an engine mount in service undergoes several complex loading conditions. The nonlinear elastic behavior of this elastomer part is commonly modeled by non-linear hyperelastic constitutive equations. Qualities required for a constitutive model are a small number of material parameters, a cover of the largest range of strain and being based on few simple tests (Steinmann et al. 2012). It was already highlighted that an identification of constitutive equations based on only uniaxial tension experiments fails to accurately predict others loading conditions (Seibert & Schöche 2000, Boyce & Arruda 2000, Attard & Hunt 2004, Marckmann & Verron 2006). In order to overcome these poor predictions, identifications are often enriched with several homogeneous experimental tests: compression or equibiaxial tests, pure shear, simple shear. Nevertheless, running all these tests is not an easy task since it requires different specimens and set-ups.
