Adhesion enhancement in Al/PMMA joints under dynamic loading: Effects of adhesive thickness and strain rate

Metal/polymer adhesive joints, valued for their high strength and lightweight properties in automotive components, are susceptible to debonding under dynamic loading, potentially compromising vehicle safety and reliability. The unclear evolution of bond strength with adhesive layer thickness (ALT) under dynamic loading necessitates further investigation to enhance bond strength. We systematically investigate the effects of the ALT and strain rate on the bond strength and reliability of aluminum (Al)/polymethyl methacrylate (PMMA) joints under dynamic loading. Using split Hopkinson pressure bar (SHPB) experiments and high-speed camera imaging, we observe that, contrary to the trend under quasi-static loading, the joints achieve maximum bond strength at a strain rate of ∼650 s −1 and the corresponding ALT of approximately 1.00 mm, which is 331.5% higher than that of the joints within a thinner ALT. The failure mechanisms of joints with different ALTs are revealed through a combination of experiment and simulation. Under the optimal ALT, the failure mechanism changes from interfacial failure to mixed failure due to the change of stress distribution. This study can provide valuable insights and theoretical foundations for the structural design and operational reliability of high-strength adhesive joints under dynamic loading.