A crystal plasticity phenomenological model to capture the non-linear shear response of carbon fibre reinforced composites

A hardening response is often observed for shear-dominated large deformation of Carbon Fibre Reinforced Plastics (CFRP). This non-linear response is often modelled by fitting a strain hardening lawagainst experimental stress-strain curves. Inspired by a crystal plasticity framework, a phenomenologicalmodel is developed to capture matrix shearing and fibre rotation of CFRP under finite strain. Thisphenomenological model is first verified by simple shear and transverse compression tests, followed bycomprehensive validations against measured stress-strain responses of unidirectional (UD) and cross-plycomposite laminates subjected to quasi-static loading. The analytical and finite element predictions ofCFRP lamina under simple shear loading confirm that the initial yielding is governed by the shear yieldstrength of the matrix, while the hardening behaviour is dependent on the modulus and rotation of thecarbon fibres. This model accurately predicts the non-linear behaviour of CFRP under off-axis loadingwithout the need of an empirical curve-fitted strain hardening law.