An experimental investigation of the effect of interface adhesion on the fracture characteristics of a brittle-ductile layered material

The effect of interface adhesion on the failure characteristics of brittle-ductile layered material was experimentally investigated. Single-edge-notched fracture specimens were prepared by bonding two Homalite-100 layers to a thin aluminum layer using three different types of adhesives. The specimens were loaded under three-point bending and photoelasticity was used for full-field observation of the failure process. Fracture tests revealed two competing modes of failure: delamination along the Homalite-aluminum interface, and crack re-initiation in the Homalite layer across the reinforcing aluminum layer. The failure modes were directly influenced by the characteristics of the adhesive bond. Maximum load retention and energy dissipation capability during the fracture process was observed for a urethane based adhesive that formed an interfacial bond that was resistant to delamination, and additionally exhibited low modulus and large strain-to-failure, thereby suppressing crack re-initiation.