Experimental studies on adhesively-bonded scarf joints: influence of natural ageing on progressive damage

This work characterizes the effects of natural ageing on the micro-mechanical behaviour of two adhesively-bonded scarf joints. The samples studied are made of XC18-type steel with different scarf angles (33 and 6°) and the adhesive is an epoxy resin. Contrary to most experimental studies which determine the strength of bonded joints in terms of their failure load, in this study sensitive strain gauges have been used to measure progressive damage of the adhesive joints. The results show that the damage is closely linked to the mechanical and geometrical properties of the test joints and that ageing increases the load thresholds of the first microcracks initiation and the ultimate failure of both adhesively bonded scarf joints.