EFFECTS OF FIBER AND INTERPHASE ON MATRIX-INITIATED TRANSVERSE FAILURE IN POLYMER COMPOSITES

Failure initiation in polymer-matrix composites loaded transverse to t he fibers is investigated by a numerical parametric study where the ef fects of constituent properties, interphase properties and thickness a ve examined. Failure initiation in the matrix only is studied, interfa cial debonding not being considered. Two modes of failure-yielding and cavitation-induced brittle failure-are examined. A criterion for the cavitation-induced brittle failure has been proposed previously and fa ilure prediction based on this criterion was found to agree with exper imental data for a glass-fiber-reinforced epoxy. The present study sho ws that the elastic modulus of fibers has a large effect on the stress and strain to failure initiation. A rubbery interphase material is fo und in most cases to have a beneficial effect. The site at which failu re initiates and the governing mode of failure initiation ave also aff ected by the fiber modulus and the interphase properties. (C) 1996 Els evier Science Limited