The fatigue behaviour of a glass-fabric-reinforced polyester resin under off-axis loading

Abstract

Off-axis strength tests were conducted on polyester resin laminates reinforced with a balanced plain-weave glass fabric (Tyglass Y449) under static tension and compression and zero-tension stress, zero-compression stress, and fully-reversed stress fatigue. In each case the onset of initial damage was observed as well as rupture of the specimens. The results were compared with a number of well-known failure theories for combined stresses. When the off-axis strengths were compared with curves computed from the failure theories, only those items which had additional constants evaluated from combined stress data appeared to fit the results satisfactorily. Further examination of the failure surfaces for the Tsai and Wu (1971) theory revealed that this fit was only local.