Damaging processes in polypropylene compound: Experiment and modeling

The aim of this paper is to present a procedure of construction of constitutive equations within the framework of Continuum Mechanics. The main focus of our effort is to introduce the geometric change at a high level of strain and the damage which are generally developed in simple tests (tension, shear) of polymeric materials such as polypropylene compounds or copolymers (PP). High-resolution strain-mapping techniques are employed to determine the surface strain fields and, consequently, a measurement of the volume change. A phenomenological model based upon experimental observations was developed to reproduce the main behavior, e.g., the stress strain curves, including the volume change and their consequences. State Variables are defined and related to their evolution in relation with the state laws. The identification of the resulting model was made by reproducing the data issued from basic tests (Tension, Iosipescu Shear).