Cu-Al异种金属超声焊接过程模拟

利用有限元方法建立了Cu-Al超声焊三维热—力耦合模型. 热源包括摩擦热和塑性变形热，其热流密度与焊接不同阶段材料的振幅相关. 焊接过程超声变软影响温度场分布、应力、应变场和齿的嵌入，模拟合理考虑了铜、铝超声变软的数学模型. 模拟结果表明，铜和铝的块体温度均低于熔点，最高温度出现在焊头与铜板的接触面中心；Cu-Al连接界面最高温度出现在焊接区域中心处. 同时也模拟了齿的嵌入，焊接过程中焊头齿完全嵌入铜表面，但底座齿并未完全嵌入铝中. 与热电偶测温和焊接截面形貌对比验证表明，模拟结果与实际基本吻合，较好地模拟了超声变软、热和力三者之间的作用.

Modeling of ultrasonic metal welding of Cu-Al joints

A 3-D thermal-mechanical coupled finite element model of ultrasonic metal welding of dissimilar alloys is developed. The friction heat flux and the deformation heat flux are related to different level of coupon’s vibration amplitude. The effects of ultrasonic softening on temperature distribution, stress distribution and tool indentation depths are included in the analysis of the welding process. The results show that the bulk temperature is lower than the melting temperature of the metals, the maximum temperature occurred at the center of the contact interface between the sonotrode tip and the upper copper specimen and the peak level of the welding interface temperature occurred at the center area. It is also shown that the sonotrode tip completely sinks into copper in welding, while the anvil tip’s indentation depths do not reach its maximum. The proposed model is validated and verified by comparing with welding cross section and a point temperature using experimental physical test. The presented model is capable of predicting and explaining the relationship between ultrasound soften, mechanical field and thermal field during welding process.