On the Stress Triaxiality Sensitivity of High Density Polyethylene

The aim of this paper is to investigate the stress triaxiality effect on the yield stress for the high density polyethylene (hdpe). An experimental protocol has been established to get a wide range of stress triaxialities (negative and positive). Tensile tests, uniaxial compression and simple shear were performed on specimens with different geometries: notched round bar specimens with different curvature radii, cylindrical specimens and parallelepiped specimens respectively. Biaxial tests (combinations of tensile/compressive and shear loading) are also achieved on butterfly-shaped specimens using an Arcan apparatus in order to expand the stress triaxialities. The experimental results demonstrate that the yield stress depends on the stress triaxiality which is due to the hydrostatic stress influence.