The influence of adhesive reinforcement on the Mode-I fracture toughness of a bonded joint

The influence of adhesive reinforcement on the Mode-I fracture toughness of a double-cantilever beam specimen has been investigated. An analytical model based on Reissner's variational theorem, which has previously been shown accurately to predict stress fields and energy release rates for cracked laminates, was used to model the test specimen. A plane-strain model was developed and used to determine the energy release rates for mid-plane cracks in aluminum-adherend bonded specimens with varying amounts of reinforcement in the adhesive. The energy release rates determined from the present model, which was used to determine fracture toughness for specimens in a systematic experimental program, compared favorably to results of closed-form analyses from the literature. The amount of reinforcement in the adhesive layer has been shown to have a significant effect on the Mode-I adhesive fracture toughness and cracking behavior.