磁脉冲焊接飞管变形过程数值模拟

Numerical simulation of flyer tube deformation during magnetic pulse welding

建立了管-管磁脉冲焊接飞管变形过程的有限元-边界元分析3D模型,利用ANSYS/LS-DYNA软件的电磁场-结构场-温度场耦合求解方法,分析了管端搭接位置和放电电流频率对飞管变形规律的影响。研究结果表明,管-管磁脉冲焊接飞管变形过程可分为3个阶段,即初始阶段、均匀缩径阶段和冲击接触变形阶段。当飞管的端部外伸出集磁器工作区时,飞管的外端(未变形的金属)对均匀缩径变形区金属的影响主要是形成大的碰撞角度、减小碰撞速度。飞管管端适当缩进集磁器工作区可使飞管上的电磁力呈梯度分布,有利于碰撞角度的形成,实现焊接的效果。温度分布结果表明,磁脉冲焊接界面温升应是多因素的综合结果,飞管的宏观塑性变形功和涡电流的焦耳热并不是实现磁脉冲焊接界面结合的唯一热源。在放电能量一定的条件下,提高放电电流频率,有利于缩短初始阶段时间,提高接触碰撞速度。

A 3D finite element and boundary element analysis model was established to simulate the flyer tube deformation during magnetic pulse welding of tube-to-tube.Based on the coupled electromagnetism-structure-temperature solver of the ANSYS/LS-DYNA software,the effects of lap position and discharging current frequency on the deformation behavior of the flyer tube were investigated.The research results show that the deformation process can be divided into three stages,namely,initial stage,uniform compression stage and collision stage.The main influence of the undeformed metal of the flyer tube on the uniform compression deformation zone is to generate a large collision angle and reduce the collision velocity,while the end of the flyer tube exceeds the work zone of the field shaper.Electromagnetic force applied on the flyer tube has a gradient distribution in the case of that the end of the flyer tube is appropriately retracted into the work zone of the field shaper,which is favorable to the generation of collision angle and achieve welding effect.The temperature distribution results show that the temperature rise in the magnetic pulse welding interface is attributed to a comprehensive result of multiple factors.The work of macroscopic plastic deformation of the flyer tube and the joule heat of the eddy current are not the only heat source for the bonding of magnetic pulse welding interface.Increasing the discharging current frequency is beneficial to shorten duration of the initial stage and increase the contact collision velocity under the condition that the discharge energy keeps constant.