Plasticity Effect On The Mechanical Behavior Of An Amorphous Polymer

In the process of forming solid materials, the plastic instability phenomena often control the appearance and performance of the finished product. The study of these phenomena is therefore of great scientific and technological importance. Polymers materials, for example, polyvinyl chloride (PVC) are frequently used in the pipelines, which require details that are more serious, it is therefore essential to understand the mechanisms of plastic instability in order to know how to control them.And for this, the true stress-strain response under large plastic deformation was investigated in different stress triaxiality frameworks. A particular attention was given on the volumetric strain evolution and the damage. The effect of stress triaxiality on the fracture strain was also examined. In the second part of this paper, an elasto-viscoplastic behaviour model is presented, with non associated plasticity, damage and coalescence, which represents the observed behaviours of a PVC material under different triaxialities and for three initial void shapes. We can conclude that the mechanical behavior of PVC is very marked by the effect of the stresse triaxiality as evidenced by the volumetric deformation levels reached. It is a damaged elasto-plastic behavior.