电场辅助焊接过程电热耦合场仿真

Numerical simulation of electrical-thermal coupling field of electric field assisted welding process

  • 摘要:
    目的 电场辅助也即脉冲电流辅助焊接(简称SPS焊接),是一种集电阻加热、等离子活化、电致扩散、热压为一体的多物理场高度耦合的连接方法,具有焊接时间短、温度低、变形小、连接质量优异等特点,应用潜力巨大。旨在研究焊接材料导电性、高温性能、接触界面电阻、模具形状、装样顺序等各方面影响因素对焊接产热、电流分布的影响规律。
    方法 文中采用MSC.MARC软件,探索SPS焊接电热耦合场有限元模拟算法,定量、动态分析了SPS焊接系统电场、温度场分布及焊件热循环,阐明了SPS焊接工艺机理,将数值预测结果与5A06铝合金SPS焊接工艺曲线进行了对比,验证了模型的准确性和计算精度。同时,研究了材料导电性、焊接装配对焊接系统电场和温度场的影响。
    结果 结果表明,电流优先从易导电通道流过,焊件界面接触电阻越大,流经其电流越小,电场和温度场存在耦合作用,主要产热位置变化引起焊件和模具温度不均匀性变化。当焊接材料导电性差异较大时,电场和温度场相对于焊接界面不再呈上下对称分布。
    结论 SPS焊接时,应从电场和温度场两个角度选择焊件装配方式。当系统整体电流密度更大,焊接界面温度更高,且高熔点材料温度比低熔点材料温度更高的状态同时达到时,是优先推荐的焊件装配方式。

     

    Abstract: Objective Electric field (pulse current) assisted welding, briefly SPS welding, is a multi-physical field coupling joining process that combines resistance heating, plasma activation, electric field assisted diffusion and hot pressure. It has promising wide applications owing to advantages of short time, low temperature, low deformation and good quality. The aim is to study influence of various factors such as conductivity of welding materials, high temperature performance, contact interface resistance, mold shape and loading sequence on welding heat production and current distribution. Methods In this paper, thermal/electrical coupled numerical model is established and finite element algorithm is presented based on MSC.MARC software. Temperature distribution, electric field of welding system, and thermal cycle of weldment are quantitatively and dynamically analyzed. Mechanisms of SPS welding process are elucidated. The numerical prediction results are compared with SPS welding process curve of 5A06 aluminum alloy, and validity and calculation precision of the model are verified. Furthermore, effect of electrical conductivity of material and welding assembly on electric field and temperature field of welding system are studied. Results The results show that current flows preferentially through conductive channels, and the greater contact resistance at the interface of weldment results in the smaller current flowing through it. There is a coupling effect between electric field and temperature field, and changes in the main heat generating location cause changes of temperature non-uniformity between weldment and mold. When electrical conductivity of welding materials varies greatly, electric field and temperature field no longer exhibit a symmetrical distribution relative to welding interface. Conclusion For SPS welding, assembly methods of weldment should be selected from two perspectives of electric field and temperature field. When the overall current density of the system is larger, temperature of welding interface is higher, and temperature of high melting point material is higher than that of low melting point material at the same time, which is preferred to recommend assembly method of weldment.

     

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