Finite element modelling of bending of CFRP laminates: multiple delaminations

Carbon fibre-reinforced polymer (CFRP) composites are widely used in aerospace, automotive and construction structures thanks to their high specific strength and stiffness. They can also be used in various products in sports industry. Such products can be exposed to different in-service conditions such as large bending deformation and multiple impacts. In contrast to more traditional homogeneous structural materials like metals and alloys, composites demonstrate multiple modes of damage and fracture due to their heterogeneity and microstructure. Damage evolution affects both their in-service properties and performance that can deteriorate with time. These failure modes need adequate means of analysis and investigation, the major approaches being experimental characterisation and numerical simulations. This research deals with a deformation behaviour and damage in composite laminates due to quasi-static bending. Experimental tests are carried out to characterise the behaviour of a woven CFRP material under large-deflection bending. Two-dimensional finite element (FE) models are implemented in the commercial code Abaqus/Explicit. A series of simulations is performed to study the deformation behaviour and damage in CFRP for cases of high-deflection bending. Single and multiple layers of bilinear cohesive-zone elements are employed to model the onset and progression of inter-ply delamination process. Numerical simulations show that damage initiation and growth are sensitive to a mesh size of cohesive-zone elements. Top and bottom layers of a laminate experience mode-I failure whereas central layers exhibit a mode-II failure behaviour. The obtained results of simulations are in agreement with experimental data.