Mode II fracture toughness of two-part acrylic-based adhesive in an adhesively bonded joint: end-notched flexure tests under static loading

This paper focuses on fracture toughness measured using end-notched flexure tests under Mode II static loading in aluminium alloy (5052-H34), glass fibre-reinforced polypropylene matrix composite (GF/PP) and carbon fibre-reinforced epoxy matrix composite (CF/EP) adherends bonded with DP8005 adhesive. Traction-separation relations are also presented using a cohesive zone model to estimate the fracture toughness under mixed-mode loading. The experimental results show that the fracture toughness values of the aluminium alloy, GF/PP and CF/EP specimens are 2398, 2474 and 2428Jm(-2), respectively. Fracture surface observations reveal that failure types for the aluminium alloy, GF/PP and CF/EP specimens are mainly cohesive. It can be concluded that Mode II fracture toughness shows a low degree of dependence on the different adherends bonded with an acrylic-based adhesive when cohesive failures are dominant. By assigning the experimental parameters in the failure criteria, the fracture toughness can be estimated under different mixed modal ratios.