Infrared-thermography measurement of temperature distribution in carbon fiber–reinforced polypropylene during ultrasonic welding

Abstract

Herein, the temperature distribution during ultrasonic welding of carbon fiber–reinforced polypropylene (CF/PP) was investigated. The temperature distribution was assessed using a thermographic camera that specifically targeted the lateral aspect of the welded section of the adherend in the lap joint. In addition, single lap shear tests were performed on the resulting welded joints. The welding experiments confirmed that the amplitude of the sonotrode impacts both the temperature distribution during welding and the quality of the joint, eventually affecting the mode of failure. By applying the half-width method to the measured temperature distribution in the thickness direction of the adherend, we assessed the spread of the high-temperature region centered on the welding interface. In this study, at a small amplitude (36 μm), the half-width of the maximum temperature showed approximately twice higher slope than at other amplitudes, indicating a wider high-temperature range even at the same interface temperature.