Accelerating environmental ageing effects of adhesively bonded aluminium joints by using smaller bonding areas

In all areas of application, adhesive joints are exposed to environmental conditions, which can weaken the joint. To verify the functionality of the joints for a certain service life, accelerated ageing tests are used. To assess the mechanical performance of aged joints, single lap joints (SLJ) are often used. The influence of various geometries of SLJ on the strength and stress behaviour is known. The various ageing processes in bonded joints are not yet sufficiently known. Thus, the influence of the specimen geometry on the ageing behaviour cannot be reliably estimated and is therefore investigated in this work. SLJ with different geometries made of an AlMgSi alloy and a one-component epoxy-hybrid adhesive were artificially aged. T dimensions of the SLJ were varied in width, overlap length, adhesive thickness or joint design. Similar ageing results were seen in a significant shorter time with narrower samples or shorter overlap length. A SLJ with a bonding area of 6.3 mm x 6.3 mm was derived from these results. After 4-5 weeks of ageing, this shows comparable results to the standard test SLJ after 8 weeks. This allows to speed up industrial ageing tests nearly by factor two without changing ageing mechanisms.