Experimental and numerical studies on AFRP-reinforced thin-walled tubes under axial impact loading

With the increase in global threats to infrastructure, from unforeseen events particularly in steel structures, there is a growing urgency to strengthen the impact resistance of steel elements. This research aimed to investigate the potential of using AFRP (Aramid Fiber Reinforced Polymer) to improve the energy absorption and crushing resistance of thin-walled circular hollow steel (CHS) tubes subjected to axial impact loads. Key aspects of the investigation include conducting a series of experiments to evaluate the impact of AFRP layer thickness, steel tube thickness, and impact velocity on structural performance. The performance metrics were characterized by analyzing impact force versus displacement, energy absorption capacity, peak crush load, and mean crush load. The results show that AFRP strengthening significantly enhances peak load capacity, energy dissipation, and impact force absorption compared to plain steel tubes. The AFRP-strengthened specimens exhibit higher specific energy absorption (SEA) and crushing force efficiency (CFE) compared to non-strengthened specimens, with peak force increasing by 18 % to 160 % for low external energy and 14 % to 190 % for high external energy. The threedimensional finite element (FE) model accurately predicts load-carrying capacity and AFRP failure, validated against experimental tests. This study provides quantitative evidence of the effectiveness of AFRP reinforcement in improving the crash performance of thin-walled tubes under axial impact loading, highlighting the potential for optimizing AFRP strengthening techniques in structural applications.