The effects of matrix and interface on damage in CRP cross-ply laminates

A study has been made of the transverse cracking behavior of a series of cr oss-ply laminates with different matrices, fiber coatings (sizes) and fiber volume fractions. On the basis of unpublished results, a correlation was a ssumed between material effects on leakage pressure in pressure vessels of given stacking sequence and transverse cracking behavior in cross-ply lamin ates. Mechanisms for crack initiation and growth were studied by optical mi croscopy. The strain ai the onset of transverse cracking, epsilon(TOS), inc reased and the slope, K. of the curve of crack density as a function of str ain decreased as the G(IC) of the matrix increased. Improved fiber/matrix a dhesion and lower fiber content had similar effects. The properties of poly ester-based composites were usually inferior to those of vinylester composi tes as a consequence of pre-existing debonds and subcritical cracks resulti ng from microlevel curing stresses. From observations of failure mechanisms one may infer that proof testing of pipes or pressure vessels will increas e the extent of subcritical damage in the material. (C) 2000 Elsevier Scien ce Ltd. All rights reserved.