Toughening of thick bonded interfaces through architected crack-arresting features

[Display omitted] •Crack-arresting features (CAF) are integrated into thick GFRP adhesive joints.•CAFs significantly enhance Mode I fracture and fatigue performance of thick joints.•In pristine joints, cracks always kink from the bondline into composite adherends.•Crack kinking introduces a significant Mode II component.•Thick DCB joint configuration exhibits high positive T-stress at the crack tip. This research investigates the application of additively manufactured crack-arresting features (CAFs), designed from tough and soft polymers, in enhancing the performance of thick glass fiber-reinforced polymer composite-epoxy adhesive joints found in wind turbine rotor blades. Mode I fracture and fatigue behaviors of these joints are assessed through double-cantilever beam experiments and compared against pristine joints. In pristine joints, cracks consistently deviate from the adhesive bondline into the composite adherend, causing a sudden increase in strain energy release rate. Finite element models based on linear elastic fracture mechanics are employed to provide insight into this behavior. Experimental results demonstrate that joints with architected CAFs achieved higher strain energy release rates, more stable failure mechanisms, and minimized damage to the composite adherend. Under fatigue loading, joints featuring tough CAF material exhibit slower fatigue crack growth compared to both pristine joints and those with soft CAF material.