Reinforcing Effect by Carbon Fibers for Energy Director on Ultrasonic Spot Welding of Woven-CF/PPS Laminates

Abstract

This study aims to reveal the ultrasonic spot welding behavior and joining strength of carbon fiber reinforced thermoplastics (CFRTP) using carbon fiber reinforced energy director. The materials used for spot welding are woven carbon fiber reinforced poly phenylene sulfide (woven-CF/PPS) laminates and energy director consisting of spread carbon fiber and PPS polymer. The ultrasonic oscillator for the ultrasonic spot welding process has an oscillation frequency of 40 kHz and a maximum output of 600 W. The welding load and push-in amount of ultrasonic horn during welding process were precisely controlled by using an electric servo press machine. The effects of welding load and carbon fiber volume fraction in energy director on ultrasonic welding behavior and actual tensile shear strength were investigated to reveal the welding behaviour. The welding load and push-in amount of the ultrasonic horn was measured by a data logger. The welding part was evaluated by image analysis and cross-sectional observation using microscope. From the experimental results, it was revealed that the carbon fiber volume fraction in the energy director was significantly affects the ultrasonic welding behavior. According to the results of single lap tensile shear test, it was found that the actual tensile shear strength was increased by the addition of spread carbon fiber.