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 ( Kc) determined. For a unidirectional fabric reinforcement with the crack positioned parallel to the fibres Kc did not depend on crack length. For chopped strand mat and balanced weave fabric reinforcement Kc increased with crack length. Using an equivalent yield stress corrected values of K c independent of crack length were determined. Using the corrected Kc values the failure of specimens containing a circular hole was predicted with reasonable accuracy.