Void growth and damage ahead of a crack in pressure-sensitive dilatant polymers

The deformation of amorphous polymers is highly sensitive to hydrostatic pressure and the plastic flow is non-volume preserving. Failure of these materials is often preceded by the formation of small crack-like defects known as crazes, bridged by the fibrils of the polymer. In this work, a population of discrete voids is placed ahead of a crack within a boundary layer configuration to study the effects of pressure-sensitivity a and plastic dilatancy β on void growth and damage in polymeric materials. Results show that high pressure-sensitivity significantly increases both the intensity and spatial extent of damage, which could promote crazing. These effects can be compounded as the deviation from the associated flow rule, |β- α|, increases. This study offers some evidence of pressure-sensitivity and plastic dilatancy as the major contributing parameters to the formation and growth of microporous crazing zones in polymers.