TRI-AXIAL FAILURE THEORIES FOR FIBRE REINFORCED COMPOSITES

摘要

Attempts have been made in this paper to apply some of the better-known failure criteria for polymer composites to predict the failure of a continuous fibre reinforced/epoxy unidirectional lamina subjected to a triaxial state of stress. The test data, against which these criteria have been assessed, were generated by applying longitudinal tensile and transverse compressive loads to the lamina, in the presence of superposed hydrostatic pressures up to a magnitude of 850MPa. Additional data were also obtained describing the compressive strength behaviour of the epoxy resin. The interaction coefficients in Tsai's criterion, which were established for 2D stresses, result in conservative predictions when applied to 3D loading situations. The concept employed by Puck's theory, which considers the angle of the action plane under pressure, was observed to be crucial in understanding the pressure dependency of the transverse compressive strength. It is thus concluded that some of the theories developed to predict failure under 2D loading situations can be applied to 3D with some degree of success, but that they require further validation and benchmarking.