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Abstract

The fracture energy dissipated by a crack growing in a composite material can be in°uenced by di®erent material parameters which are a®ected by the manufacturing process. In case of brittle composite materials, failure mechanisms like debonding of the matrix-¯ber interface or ¯ber breakage can result in crack de°ection and hence in the improvement of the damage tolerance of the material. While some material parameters a®ect dissipative processes during crack growth, others in°uence the crack path. Concerning simulations of crack growth the cohesive element method provides a framework to model the fracture considering strength, sti®ness and failure energy in an integrated manner. The combination of the usual variational formulation of the elasticity problem with the Discontinous Galerkin (DG) method allows to insert cohesive elements between continuous elements wherever fracture is to be expected. Thereby one cohesive element is just opened if the stress measured at the sides of that element exceeds the known value of critical stress of the considered material. So using the DG method allows to keep the calculation e®ort low while the crack may develop quite freely. Our aim is to investigate the in°uence of di®erent cohesive zone parameters and di®erent geometries on the fracture path and energy dissipation to ¯nd optimal conditions for energy dissipation and mechanical stability of the microstructure.