Critical Stress Intensity Factors Applied to Glass Reinforced Polyester Resin

Abstract

Geometrically similar double edge-notched fracture toughness speci mens of glass reinforced polyester resin were tested and the critical stress intensity factor ( K c ) determined. For a unidirectional fabric reinforcement with the crack positioned parallel to the fibres K c did not depend on crack length. For chopped strand mat and balanced weave fabric reinforcement K c increased with crack length. Using an equivalent yield stress corrected values of K c independent of crack length were determined. Using the corrected K c values the failure of specimens containing a circular hole was predicted with reasonable accuracy.