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

Abstract

In this work, both experimental and theoretical analyses are presented of the influence of the scarf angle (α) on the micro-mechanical behaviour of 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 specimens, but also characterizes the various stages of the gradual adhesive damage and takes into account the threshold for the initiation of the first microcracks and the threshold for the start of flaw propagation as the fundamental parameters. These thresholds were determined by two experimental methods used simultaneously: extensometry with electrical strain gauges, and acoustic emission. Some of the experimental results are also compared with some theories that the authors have developed previously in this field, in order to determine their limits of application.