Repairing Ultrasonic Welded Carbon Fiber-Reinforced Nylon 66 Composite

In this study, a method for repairing partially welded carbon fiber-reinforced nylon 66 composite joints with ultrasonic welding was developed. The method included positioning the ultrasonic horn and anvil proximate the weld, and applying an ultrasonic vibration at substantially the same location on the existing welds fabricated by introducing a separation of 0.7 mm (0.03 in.) between 4-mm- (0.16-in.-) thick carbon fiber-reinforced nylon 66 workpieces. Welding tests were performed and the welded joints were quasi-static tested and analyzed. It was found that the separation between the workpieces influenced the contact between them, and consequently resulted in variations in weld area and weld strength. The welds were repaired by applying the second ultrasonic vibration with the proper energy intensity under the same horn pressure. The application of a second ultrasonic vibration not only restored the joint strength but also decreased the scatter in strength of the welds. Microstructure analyses of the repaired welds revealed the main mechanism for repairing the ultrasonic welds was the increase in weld area caused by melting of the materials at the periphery of the existing weld between the workpieces. The application of the repair method would reduce the potential need to scrap the particular component assembly.