Behavior of PVC and HDPE under highly triaxial stress states: An experimental and numerical study

Abstract

This paper addresses the deformation of axisymmetric tensile bars, made of mineral-filled PVC and HDPE, with and without pre-machined notch. The purpose of the study is both to investigate the mechanical behavior under various stress triaxialities, induced by different notch radii, and the capabilities of a phenomenological constitutive model. The yield stress and the plastic dilation have been chosen as the key response parameters from the tests in order to evaluate the yield function and the flow potential of the constitutive model. It is found that the yield stress and the plastic dilation of the mineral-filled PVC are highly sensitive to hydrostatic pressure. The yield stress of the HDPE hardly changes, while the plastic dilation increases with increasing stress triaxiality. The experimentally observed plastic dilation of both materials is related to void growth. The constitutive model reproduces force–displacement relationships for both materials with reasonable accuracy. However, the numerical simulations underestimate the plastic dilation for high stress triaxialities.