An efficient ERR-Cohesive method for the modelling of delamination propagation with large elements

The accurate modelling of delamination propagation is necessary to numerically assess the behaviour of layered materials during failure. Many available methods present computational limitations for large structures. Conventional cohesive zone modelling implies using a fine mesh, typically smaller than 1.0 mm, since several elements are needed inside the fracture process zone. This article presents an ERR-Cohesive method to model delamination in elements larger than the fracture process zone. The crack propagation is determined with an estimation of the energy release rate by means of the virtual crack closure technique. To progressively open the crack along the element length, a nodal cohesive law is introduced. The novel cohesive formulation allows to smoothly release the interface while dissipating the appropriate amount of energy. Accurate results have been obtained in double cantilever beam, end-notched flexure and mixed-mode bending tests with regular and irregular meshes for element lengths from 2 mm to 8 mm.