Two- and Three-Dimensional Finite Element Analyses of Crack Fronts in a Multidirectional Composite ENF Specimen

Results are presented from a numerical investigation of the effect of the shape of the delamination front on energy release rate distribution in a laminated carbon fibre reinforced epoxy end-notched flexure test specimen. The deformation behaviour of the specimen has been computed by threedimensional nonlinear finite element analyses using a recently developed layered 3D-shell element. The distributions of the local mixed mode energy release rates along the initial straight and one measured curved delamination fronts have been determined by the virtual crack closure method. The dependency of computed total energy release rate as well as the individual mode contributions from the shape of the delamination front is discussed. By means of 2D models for which a delamination process element has been used, a curved front was iteratively determined along which the total energy release rate is constant. The shape of this front is in good agreement with experimentally observed front shapes.