Behavior of Adhesively Bonded Steel Double-Hat Section Components under Lateral Impact Loading

Recent experimental studies on the behavior of adhesively-bonded steel double-hat section components under axial impact loading have produced encouraging results in terms of load-displacement response and energy absorption when compared to traditional spot-welded hat- sections. However, it appears that extremely limited study has been carried out on the behavior of such components under transverse impact loading keeping in mind applications such as automotive body structures subject to lateral/side impact. In the present work, lateral impact studies have been carried out in a drop-weight test set-up on adhesively-bonded steel double-hat section components and the performance of such components has been compared against their conventional spot-welded and hybrid counterparts. It is clarified that hybrid components in the present context refer to adhesively-bonded hat-sections with a few spot welds only aimed at preventing catastrophic flange separations. For gaining confidence on experimental responses, steel tubes of square cross-section have at first been subjected to transverse impact tests. Good correlation has been found between experimentally determined peak and mean loads for a square-section steel tube and those predicted numerically. The performance of adhesively-bonded components under lateral impact is found to degrade somewhat compared to conventional spot-welded hat-sections in terms of mean loads sustained, although not alarmingly for the current test conditions. It is, however, noted that flange separation observed in purely adhesively-bonded hat-sections can be an issue in terms of erosion in confidence on structural integrity of such members which can be restored by adding sparse spot-welds to adhesively-bonded flanges as also shown in the current study.