Influence of the scarf angle value upon the micro-mechanical behavior of the scarf-joint bonded structure

In this work, we are presenting the experimental and theoretical analysis o f the influence of the scarf angle value (alpha) upon the micro-mechanical behavior of the scarf-joint bonded structure loaded in uniaxial tension. Th e specimens studied are made of mild steel for the adherends and of a epoxy resin for the adhesive. Unlike most studies which only take the ultimate s trength into consideration, we characterize the various stages of the adhes ive gradual damage and we consider the threshold of the first microcracks i nitiation (symbolized Fd) and the threshold of the start of flaw propagatio n (symbolized Fg) as the fundamental parameters. The Fd and Fg thresholds a re determined by two experimental methods used simultaneously : extensometr y with electrical strain gauges and acoustic emission. We have also compare d a part of our experimental results with some of the main existing theorie s in this domain in order to determine their fields of application.