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Indexed by:会议论文

Date of Publication:2018-01-01

Included Journals:CPCI-S

Volume:76

Page Number:89-93

Key Words:Ultrasonic welding; Dynamics; Nonlinear contact model; Harmonic balance method

Abstract:Ultrasonic welding is a widely used industrial technique whereby high-frequency ultrasonic vibrations are locally applied to two or more workpieces being held together under pressure to create first heat and ultimately a solid-state weld. In the welding process, stick, slip and separation occur at the interfaces between adjacent workpieces. Thus, friction forces create a strongly nonlinear process. In addition, since several material properties are temperature dependent, the structural dynamics and the heat transfer are highly coupled. The time scale for the dynamics of the temperature field is much slower than the time scale for the mechanical vibrations. Therefore, structural vibrations reach their steady-state very quickly compared to the thermal field, and material properties can be considered to vary only quasi-statically when analyzing the vibratory motion. Consequently, we decouple the welding process into steady-state structural vibrations and transient heat conduction. In this study, a new methodology is proposed to predict the friction forces by introducing a nonlinear contact model and simulate the coupled thermal-mechanical interaction. Mixed programming of MATLAB and ANYSYS is developed with a harmonic balance method and finite elements which is able to solve the nonlinear problem and speed up the calculation significantly compared to traditional time-marching approaches. The results obtained in this study provide new understanding of ultrasonic welding from the standpoint of nonlinear dynamics. (C) 2018 The Authors. Published by Elsevier B.V.