The influence of the bevel angle on the micro-mechanical behaviour of bonded scarf joints

In this work, both experimental and theoretical analyses are presented of t he influence of the scarf angle (alpha) on the micro-mechanical behaviour o f a scarf-joint bonded structure loaded in uniaxial tension. The specimens studied were made of mild steel for the adherends and of an epoxy resin for the adhesive, This study not only considers the ultimate strength of the s pecimens, but also characterizes the various stages of the gradual adhesive damage and lakes into account the threshold for the initiation of the firs t microcracks and the threshold for the start of flaw propagation as the fu ndamental parameters. These thresholds were determined by two experimental methods used simultaneously: extensometry with electrical strain gauges, an d acoustic emission. Some of the experimental results are also compared wit h some theories that the authors have developed previously in this field, i n order to determine their limits of application.