Abstract: On the basis of the natural rule that the stress carried by a material cannot surpass its strength, the authors hypothesize that a composite exhibites equivalent elastic-plastic insitu behavior and present a method based on linear finite element analysis (FEA) to simulate the gradual failure process and notched strength of a composite laminate with a central hole. In this simulation, considering the scatter of the material in practical structure, the material properties of each element are randomly distributed. Hashin failure criteria are adopted to determine the failure states of the material in the elements, and the elastic constants of the failed material are degraded according to their failure patterns. The strength of five kinds of Eglass/epoxy composite laminates with a central hole is tested by experiment, and, on condition of no separate consideration of the delamination effects, their predicted strengths are found to agree well with the experimental results. Compared with traditional strength prediction methods based on FEA, the current method avoides artificial determination of the reduction factor of failed material.

Key words: composites, laminates, central hole, in-situ properties, finite element analysis, gradual failure