Abstract
Ultrasonic joining is an alternative direct-assembly joining technology to produce through-the-thickness reinforced hybrid joints between surface-structured metals and unreinforced or fiber-reinforced thermoplastics. As a result, joint damage tolerance can be improved. This paper presents a preliminary evaluation on the influence of joining energy on the joint formation, microstructure and mechanical performance of Ti-6Al-4V-Polyetherimide hybrid joints. Process-related microstructural changes and mechanical performance of optimized were assessed. The ultimate lap shear force of hybrid joints was six times higher (1860 ± 260 N) than the non-reinforced reference joints (292 ± 7 N). A considerable increase of ten times in displacement at break for ultrasonic joints was also achieved in comparison to reference joints. This is an indication that joint damage tolerance was increased due to an efficient load transfer by pin interlocking between the metal and polymer parts. Initial joint failure was by bearing – a non-catastrophic failure type – while shearing of the metallic pins was responsible for the final parts’ separation during lap shear testing.
