Studies on the failure analysis of composite materials with manufacturing defects

Abstract

A strategy is discussed for the cost reduction of composite structures by allowing manufacturing defects while satisfying the performance requirements. To implement the strategy, cost/performance trade-offs must be made. These trade-offs require a proper assessment of the effect of defects on the performance-limiting conditions, such as the loss of required stiffness and/or strength. For illustration, two failure modes in composite laminates are considered: the delamination fracture and the progressive ply cracking under quasi-static loading. In the first case, the manufacturing-induced defects are treated directly by examining their effects on the energy release rate, while in the second case, the defects are taken into account indirectly via their influence on the statistics of local failure.