A Model for the Compressive Failure of Composite Materials

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Abstract
A theoretical model for the failure of a fiber/ply due to compressive loading is developed. The formulation examines the case of a dilute solution composed of a single fiber/ply embedded in an infinite plane of matrix material. This work is based on a two-dimensional analysis of a fiber/ply with or without some initial imperfection. The model analyzes the transverse displacement of the fiber/ply and the corresponding effect on the stress state of the various phases. The solution allows the possibility of interfacial failure of the composite system, as well as microbuckling of the fiber. In the interfacial failure mode, the model allows interactive effects between shearing and debonding contribute to failure. The interfacial failure criteria is based on a combined stress failure criteria for the resultant stresses at the fiber/matrix interface. The analytical results for both the fiber and ply cases are compared to experimental data and generally show excellent agreement. The results show that buckling, especially for small imperfections, is a theoretical upper bound for failure. In addition, the results indicate that interface failure instability (IFI) occurs at much lower stresses than microbuckling for typical fiber reinforced polymers.