A non-linear model for in-plane shear damage and failure of composite laminates

Composite material characterization is typically carried out by time-consuming and expensive experimental tests aimed at establishing strengths at both lamina and laminate levels. In this scenario, numerical analyses are valuable tools in order to reduce the number of tests and to gather, at the same time, knowledge about the complex interactions of the composite damage mechanisms. The paper presents a new constitutive model for the non-linear shear behavior of composite laminates, which has been implemented in an user-de ned Fortran routine (UMAT) to be used within ABAQUS non-linear FE code. A numerical model of the ASTM Standard V-notch specimen shear test has been developed in order to identify the key parameters of the non-linear shear constitutive model. This has been achieved by means of a systematic comparison of the numerical results with experimental data. Material anisotropy and the geometry of the notch have been found to cause the shear strain eld to be non-uniform in the notch section. This prevents a direct measure of the shear constitutive law parameters, which must be alternatively evaluated through an indirect procedure. A modi ed notch geometry, which mitigates strain non-uniformities, has been evaluated and assessed through numerical simulations.