Investigating joint failure mechanisms in continuous ultrasonic welding of GF/PA۶ thermoplastic composites

Continuous ultrasonic welding is a new method for joining thermoplastic composites. In this process, ultrasonic vibrations are transmitted into the composite materials, generating sufficient heat through surface and intermolecular friction to melt the composite matrix. Simultaneously, pressure is applied, and two composite plates with a specific overlap are joined together. In this research, continuous welds with varying shear strength were obtained by adjusting the main process parameters, namely power, speed, and pressure. In each experiment, the failure mechanisms of the welds were investigated using microscopic images. The results show that in high-speed welding at a speed of ۳۰ mm/s, due to the shallow penetration and low uniformity of the resulting weld, the composite polymer matrix plays the primary role in the joint. Therefore, the dominant failure modes are matrix cracking and the presence of numerous voids. At a low welding speed of ۱۰ mm/s, sufficient heat supply at the interface of the plates results in a weld with high penetration, uniformity, and strength. Therefore, the dominant mechanisms of connection failure include fiber breakage, and local peeling of the layer in contact with the interface.

کلیدواژه ها:

Continuous ultrasonic welding ، thermoplastic composite ، Joint failure mechanisms ، Joining