Evaluation of variation in the mechanical properties of composite laminates using progressive failure analysis

In this paper, the performance of some glass/vinylester composite laminates was examined. Using 3D FE models for the specimens and progressive failure analysis of the models, an accurate simulation of the contact between the composite beam and the supports was implemented. Also the influence of material and geometric non-linearity on the flexural load carrying behavior of the beams was investigated. At the first, the tension experiments were conducted for observation of the progressive failure behavior in the composite laminates and verification of the failure model. In the following, by implementing the three-point-bending tests and then simulation of the composite beam specimens, varaition of the flexural modulus was investigated by the aid of comparing the load-deflection curves obtained by the experiments and the FE models. For prediction of the failure, the strain-based failure criteria were used rather than the stress-based failure criteria. Since the failure strains were identical for tensile and bending specimens, variation of the flexural modulus led in variation of the flexural strength. As variation of the flexural modulus was considered dependent on the performance of the polymeric phase of the composite laminates, this variation was attributed to the performance of the 90˚ layers.