Mixed-Mode Cohesive Damage Model Applied to the Simulation of the Mechanical Behaviour of Laminated Composite Adhesive Joints

Abstract

A study of the mechanical behaviour of laminated composite adhesive joints is presented in this paper. The study consists of both numerical simulations and experimental tests. It concentrates on single lap-shear joints made of carbon–epoxy laminated composites and an epoxy adhesive. The main objective is to verify the adequacy of cohesive damage models for the strength prediction of bonded joints. These models are attractive in modelling fracture problems since they do not require the definition of an initial crack and they model damage propagation without any user intervention. A mixed-mode cohesive damage model is used to simulate damage onset and growth in the adhesive layer. The model is an extension of pure mode (I and II) trapezoidal cohesive damage models. The trapezoidal shape in the constitutive law is more valid when ductile adhesives are used. The mixed-mode model requires a complete characterization of the cohesive parameters in pure modes, determined with an inverse method. Tensile tests are performed for joints with different overlap lengths. It is shown that the numerical simulations represent with a reasonable accuracy the mechanical behaviour of the joints tested.