A fracture angle based three-dimensional damage model for unidirectional fibre-reinforced plastics

Since the failure analysis of fibre-reinforced plastics is not limited to the first-ply failure, it is mandatory to use adequate damage models to simulate the failure process. The paper describes a damage model for three-dimensional stress states, which uses the crack orientation of the inter-fibre fracture (IFF). The fracture angle describes the crack orientation and can be obtained by using Puck's IFF criterion. The fracture angle enables the possibility to take the causal stress situation for the IFF into account. This means that each Young's or shear modulus has its own damage function, which depends on the stress state and the fracture angle. Therefore, the stress-strain extrapolation method of Schürmann and Weber for two dimensional stress states was advanced and modified for the three-dimensional stress space.