Defect Development in Multilayer Composites under Static Loads

Algorithms for taking account of the growth of damage in multilayer composites under static loads are studied. The most common defect in multilayer structures is a transverse crack in layers with a specific orientation relative to the applied load. Two types of defect are considered: transverse cracking of the layers without the formation of a complete transverse macrocrack; and the development of interlayer cracks in the vicinity of the transverse cracks. The times at which cracks appear in the transverse layer under the action of tensile loads are determined. Attention also focuses on the propagation of the cracks and the subsequent fracturing as the load increases. Failure of a composite with transverse reinforcement is seen between the fibers because the limiting deformation there is small in comparison with that along the fibers in materials with any structure. Detailed analysis of the failure of the binder between the fibers permits prediction of subsequent defect development.