Analysis of the notch tip damage zone in biaxially oriented polypropylene

Abstract

AbstractThe circular notch tip damage zone in biaxially oriented polypropylene has been analyzed using a thickness correction to the elastic stress distribution for a sharp‐notched tension specimen. The size and shape of the damage zone as a function of applied stress followed a critical mean stress criterion, independent of specimen thickness. Also, the damage zone only grew while σ3 was greater than zero. Close observations of sections through the damage zone revealed that the circular zone, which consisted of many delamination crazes, had a distinctive pattern when viewed across the thickness difection. Large crazes grew into a triangular pattern with smaller crazes in between them. The shape developement of the triangular profile as well as the smaller crazes was explained using a stress‐redistribution argument. The growth path of the delamination crazes in the x‐z plane appeared to be in a direction perpendicular to the direction of σ3. © 1994 John Wiley & Sons, Inc.