An investigation of the ultrasonic joining process parameters effect on the mechanical properties of metal-composite hybrid joints

The ultrasonic joining process was recently introduced as an alternative concept to join through-the-thickness reinforced metal-composite hybrid structures. In this work, the investigation of joining process parameters effect on the joint mechanical performance of Ti-6Al-4V-glass-fiber-reinforced polyetherimide overlap joints was carried out by Box-Behnken design of experiments. The individual and combined effects of joining energy, sonotrode oscillation amplitude, and joining pressure on the ultimate lap shear force were elucidated by response surfaces method and analysis of variance. As a result of this study, a set of optimized joining parameters were obtained to produce joints with high ultimate lap shear force. The obtained reliable reduced model (R2 = 82%) displays a major influence of joining energy (25.3%) and sonotrode oscillation amplitude (21.2%) on the joint mechanical performance. Two-way interaction response surfaces were used to support strategies to optimize the maximum ultimate lap shear force. By comparing the optimized joint condition produced in this work with previously published results an improvement of 79% in ultimate lap shear force was attained, thereby, proving the potential of the proposed process optimization procedure.