Thermally Induced Transverse Cracking in Graphite-Epoxy Cross-Ply Laminates

Abstract

Thermally induced transverse cracking in T300/5208 graphite-epoxy cross-ply laminates was investigated experimentally and theoretically. The six laminate configura tions studied were: [0/90 3 ] s , [0 2 /90 2 ] s , [0 3 /90] s , [90/0 3 ] s , [90 2 /0 2 ] s , and [90 3 /0] s . The thermal load required to initiate transverse cracking was determined experimentally and compared to theoretical prediction. Experimental results for the accumulation of transverse cracks, under cyclic thermal loading between —250°F and 250°F for up to 500 thermal cycles, are presented. The calculated in situ transverse lamina strength was deter mined to be at least 1.9 times the unidirectional lamina transverse tensile strength. All laminate configurations exhibited an increase in crack density with increasing thermal cycles.