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A Model for Predicting Damage in Graphite/Epoxy Laminated Composites Resulting from Low-Velocity Point Impact

An investigation was performed to study the impact damage of graphite/epoxy laminated composites caused by a low-velocity foreign object. The impact damage in terms of matrix cracking and delaminations resulting from a point-nose impac tor was the primary concern. A model was developed for predicting the initiation of the damage and the extent of the final damage as a function of material properties, laminate configuration and the impactor's mass. The model consists of a stress analysis and a failure analysis. A transient dynamic finite element analysis was adopted for calculating the stresses and strains inside the composites during impact resulting from a point-nose im pactor. Failure criteria were proposed for predicting the initial intraply matrix cracking and the size of the interface delaminations in the composites. Experiments were also per formed to verify the model and the computer simulations. The predictions agreed fairly well with the test data.