Void growth in calciumcarbonate filled PVC

Abstract

SIMLab has in recent years been developing a constitutive material model for polymer materials. Polymersoften experience volume change during plastic deformation, which is often related to damage in the material, such as micro cracks and void development. A disadvantage with the material model is that it does notcapture the volume change or the damage correctly.

This thesis presents an investigation of void growth in calcium carbonate filled polyvinyl chloride. Themacroscopic behavior of the material was tested by uniaxial tensile testing, where digital image correlationwas applied to measure the strain fields on the surface of the test specimen.

The microscopic void growth in each test specimen was analyzed in a scanning electron microscope and processed by image analysis. The void development was researched and compared with the macroscopic behavior of the material gathered from the mechanical testing. The volume strain from the mechanical testing was compared to the volume strain based on the void size observed in the micrographs.

In this study various assumptions for the shape of the voids and the particles in the material has been investigated in relation to the volume strain. This study shows that void growth as measured from micrographs is correlated with the observed volume strains from the mechanical testing.