Behavior of Adhesively Bonded Steel Double Hat-Section Components under Axial Quasi-Static and Impact Loading 2016-01-0395

An attractive strategy for joining metallic as well as non-metallic substrates through adhesive bonding. This technique of joining also offers the functionality for joining dissimilar materials. However, doubts are often expressed on the ability of such joints to perform on par with other mechanical fastening methodologies such as welding, riveting, etc. In the current study, adhesively-bonded single lap shear (SLS), double lap shear (DLS) and T-peel joints are studied initially under quasi-static loading using substrates made of a grade of mild steel and an epoxy-based adhesive of a renowned make (Huntsman). Additionally, single lap shear joints comprised of a single spot weld are tested under quasi-static loading. The shear strengths of adhesively-bonded SLS joints and spot-welded SLS joints are found to be similar. An important consideration in the deployment of adhesively bonded joints in automotive body structures would be the performance of such joints under impact loading. Due to the brittle nature of adhesively-bonded joints as compared to conventional joining techniques especially welding, the viability of such joints for meeting vehicle crashworthiness requirements has been suspect. In the current study, with the aid of the same steel sheet metal and adhesive used in the joint coupon tests, the performance of adhesively bonded double hat-sections components is compared with that of conventional spot-welded double hat-section components under axial quasi-static loading and impact loading in an instrumented drop-weight test set-up. It is noticed that although nearly complete separation of adhesively bonded flanges resulted in impact tests, these components never-the-less performed admirably well in terms of crash metrics such as mean load and energy-absorption capability. It is also shown that for a combination of discontinuous adhesive bonding and sparse spot-welds with double the pitch of conventional spot-welds, not only the crash performance in terms of the metrics mentioned is assured, but the fear of premature collapse due to complete separation of purely adhesively bonded flanges is avoided.