The effect of transverse low-velocity pre-impact on the residual strength of Al/PEEK/CFRTP adhesive joints

• At relative bond lengths of 20/L and 25/L, it is safer to use CFRTP as the impact surface than Al as the impact surface. • At relative bond lengths of 35/L and 45/L, high and stable residual strengths are guaranteed for both CFRTP and Al as impact surfaces. However, in terms of cost savings, 35/L is a better choice. • The thermoplastic Al/PEEK/CFRTP has better impact resistance than the thermosetting FM94/Al joints. Due to their excellent impact resistance, high toughness, short forming time, and recyclability, carbon fiber-reinforced thermoplastic (CFRTP) composite materials can be blended and bonded with aluminum alloys (Al) to produce lighter structures with better impact resistance. In this study, the effects of impact energy (5, 10, 15, 20 J) and impact surface (CFRTP and Al) on Al/PEEK/CFRTP joints with different relative bond lengths (20/L, 25/L, 35/L, 45/L, where L is the length of the adherend) were explored through a combination of joint impact damage modes, energy absorption rates, residual strengths, and tensile fracture surfaces. The results showed that when the relative bond lengths were 20/L and 25/L, using CFRTP as the impact surface significantly reduced the residual strength loss of the joint. When the relative bond lengths were 35/L and 45/L, the influence of the impact surface on the joint was significantly reduced. A relative bond length of 35/L was the ideal choice for structural safety and cost savings.