Reliability Analysis of Composite Laminates by Enumerating Significant Failure Modes

Abstract

In reliability analysis of laminated composite systems, there is a need for an efficient method to distinguish the significant failure modes from the great number of possible failure modes due to the variability in both strengths and loading. Two new concepts, Minimum Failure Load (ML) and Critical Failure Load (CL), are introduced in this paper to enumerate the significant failure modes. Here ML denotes the load level under which there is little-to-none chance a layer, which is defined as laminae with the same orientation, would fail; CL denotes the load level above which the layer will definitely fail. The Weibull distribution formulation for the uniaxial strengths of a layer, the Tsai-Hill failure criterion and Monte Carlo simulation are adopted to determine the values of ML and CL. All the significant failure modes can be enumerated by comparison the values of ML and CL between layers. It has been found that there are basically two groups of failure modes for axial loading and shear loading, respectively, which can be used for selecting the significant failure modes for general in-plane loading. The overall probability of failure and reliability for the laminate as a function of load are obtained by reliability analysis. The predicted failure sequences show good consistence with the experiment results.