Study On The Delamination Of Composite Laminates Under The Impact Of In-plane And Low-velocity Load

Fiber Reinforced Plastics (FRP) is widely used in aerospace industry, automobile area and civil engineering, owing to its excellent properties, such as high specific strength and modulus and its designability. But meanwhile, various problems come out during the application of FRP in the real engineering structure. Two important issuess are the failure of composites joints under bearing load and the delamination of composite laminates under low-velocity impact.One aim of this paper is to develop a method that combines Finite Element Analysis (FEA) and evolutionary algorithms in predicting and maximizing the delamination bearing strength of composite pin joints. First, based on three-dimensional contact analysis around the vicinity of pin joints, the delamination bearing strength of joints is predicted using the modified Ye-delamination criterion. Then, the maximization of the strength is studied. To overcome the disadvantage that the optimization algorithm incorporated in ANSYS is both sensitive to the initial value and liable to get involved in the local optimum, a global intelligent optimization algorithm-Particle Swarm Optimization(PSO) is used to optimize the delamination bearing strength. The optimum design variables and delamination bearing strength are achieved under the given constraint condition and the influence of pin diameter on the optimum delamination bearing strength is investigated. The method and results in this paper can offer beneficial reference to the design of composite pin joints in the practical engineering.In this paper, cohesive zone model is used to study the delamination of FMLs under low-velocity impact. The model owns two main advantages: one is that no initial crack is needed to be assumed; another is that there is no need to remesh the model during the crack propagation. First, to validate the cohesive zone model in dealing with delamination of composite laminates, the delamination simulation is carried out under the low-velocity impact and a relative good agreement is achieved with the experimental data. Next, the delamination of FMLs is investigated under low-velocity impact and the results are compared with that of composite laminates. What's more, the effects of stacking structures and metal ratios towards the delamination of fiber/metal laminates are studied.