Experimental and numerical study of polypropylene behavior using an hyper-visco-hysteresis constitutive law

The aim of this paper is to study the mechanical behavior of three copolymer polypropylene (PP) and to use a non usual phenomenological three-dimensional hyper-visco-hysteresis (HVH) model. This model is introduced in the finite element computation software, called HEREZH++ [1]. This behavior law is particularly adapted to model cyclic loading, loading/unloading and complex loading (non-radial). Experimental tests of monotonic tension, cyclic loading–unloading and relaxation tests at various strain rates and variable levels of strain are carried out on three grades of PP molded specimens. The results obtained from these tests enabled us to identify the HVH model parameters by a least squares minimization method. The constitutive model seems to be adequateness to describe the stress–strain evolution of the studied polymers under various mechanical loadings such as the loading–unloading and the torsion tests.