An efficient model of mixed-mode delamination in laminated composites including bridging mechanisms

A refined model is developed to analyse delamination in composite laminates accounting for bridging stresses at crack faces. The analysis adopts a first-order shear deformable layer-wise kinematics for the laminate and an interface model simulating mixed-mode fracture in the presence of a bridged delamination. A penalised interface simulates adhesion between layers and provides energy release rates through its strain energy density while a two-parameter softening interface with a limit displacement models bridging stresses. Delamination evolution analysis is performed by solving the non-linear boundary value problem resulting from a stress analysis coupled with opportune propagation conditions. Numerical examples are presented for composite laminates subjected to both pure mode and mixed-mode loading conditions and the results are compared with those obtained adopting classic delamination models. Analytical formulae for energy release rate evaluation are also proposed to carry out an investigation of the main factors governing accuracy in predicting delamination growth. The proposed approach captures important effects which are not included in classic delamination models. The accuracy of the model is assessed by comparisons with 2D finite element results obtained by using delamination interface elements. The finite element model agrees well with results obtained by using the proposed approach.