Experimental Investigations of the Disbond Stopping Capability of a Novel Epoxy-Thermoplastic Bondline Architecture for Composite Joints

Abstract

A novel bondline architecture for bonded composite joints is presented. By implementing a distinct rather ductile thermoplastic phase, a physical barrier for growing disbonds is obtained and thus a more fail-safe design, respectively. Furthermore, the joint is established by using two different joining technologies, namely adhesive bonding and thermoset composite welding. A possible manufacturing technique is briefly described and assessed by means of Double Cantilever Beam (DCB) and Single Lap Shear (SLS) tests. The thermoplastic phase constrains disbonds by posing a physical barrier through a discrete change of materials. Thus, a significant increase against crack propagation is observed for DCB tests. However, visual examinations of the transition zone between both adhesive materials disclose sensitivity to a thickness mismatch between both materials leading to adhesion deficiencies in the vicinity of the thermoplast.