Abstract
Ultrasonic plastic welding is widely used for joining thermoplastic parts. The joining technique uses frictional heat and deformation heat generated by high frequency mechanical vibration to melt the plastics at the contact interface. To guarantee the successful welding, it is important to predict and evaluate dynamic behavior at the contact interface between plastic parts. In this paper, we investigate the effect of a driving frequency on dynamic behavior at the contact interface using dynamic contact analysis when an ultrasonic horn is driven at each of two different driving frequencies: 15 kHz or 19 kHz. In the contact analysis, to reproduce static pressure through the horn in the welding experiment, an upward force is applied to the fixture while sinusoidal displacement with the driving frequency is applied to the horn. The results show that the predicted dynamic behavior of the parts is in good agreement with the experimental results. From the analysis results, the relative displacement between the upper and lower parts and the elastic strain at the joint area for the 15 kHz driving frequency are larger than those for the 19 kHz. Furthermore, for the 15 kHz driving frequency, the collision phenomenon between the parts is observed. Consequently, the driving frequency significantly affects the dynamic behavior at the contact interface.
