Interfacial Fracture Toughness Measurement and Improvement for Composite/metal Interfaces

Adhesive bonding is enlarging its application range as a practical method for the joining of dissimilar materials in automotives, aircrafts, microelectronics and medical devices industries replacing conventional joining techniques such as welding, bolting and riveting [1-5]. Especially for joining of fiber-reinforced polymer (FRP) composites to other structural materials such as metal, traditional joining techniques can be inapplicable or susceptible to damage. However, adhesive-bonding can be used for many types of adherend materials and does not cause property degradation, since machining for hole fabrication for riveting or melting-point heating for welding are not required. One of the predominant concerns for engineers in using adhesive bonding is to optimize the adhesion strength. Understanding adhesion mechanisms and theoretical investigation of the influence of each mechanism on adhesion strength can fundamentally allow us to reach the formation of strong and reliable adhesive joints. The purpose of the present work is to investigate the effects of loading mode and mechanical interlocking on the adhesion strength of metal-polymer interfaces. In order to link the microscopic adhesion phenomenon to the macroscopic adhesion strength of a bonded joint, fracture mechanics concept has been utilized, and adhesion strength is measured as the required energy for fracture, i.e. the interfacial toughness.