Experimental study and FEA on composite flush-repair laminates under shear load

Experimental study was conducted to investigate the failure mode and strength behavior of composite flush-repair laminates with blind damage under shear load, and the results were then compared with those from the experiments on virgin laminates without any damage. Experimental results show that composite flush-repair laminates can recover well under shear load, and the repaired laminates have the same post-buckling load-carrying capability as the virgin laminates. Furthermore, a finite element analysis (FEA) model of composite flush-repair laminates under shear load was proposed. In this model, 3D Hashin failure criteria was adopted to identify the damages of laminates on both patch and covering layers, and zero-thickness cohesive elements were used between layers to simulate inter-laminar damage. The failure modes obtained from the model conform to the experimental results. Though the failure loads obtained from theoretical simulation do not exactly match with those from experiment, the 15% maximum deviation can still meet the demand of engineering application, due to the complexity of the design and process of flush-repair. Therefore, the proposed FEA model is able to anticipate the failure mode and failure load of composite flush-repair laminates under shear load.