搅拌摩擦点焊瞬态输入组合热源模型

Transient input combined heat source model of friction stir spot welding

为得出搅拌摩擦点焊瞬态温度场,依据摩擦学原理,建立了由均布面热源与双椭球体热源耦合的新型组合热源模型,并同时考虑搅拌针正压力与材料属性的瞬时变化。采用ABAQUS有限元软件对2 mm厚6061-T6铝合金板材搅拌摩擦点焊(FSSW)下压、停留、冷却三个阶段的温度场瞬态变化进行了数值模拟,并用焊接热循环测定实验验证了新型组合热源模型的准确性。研究了转速对于温度场的影响规律,并分析得出搅拌摩擦焊接不发生相变的机理为温度通过材料屈服应力的变化实现的负反馈调节。此新型热源模型为研究FSSW全过程温度瞬时变化及焊点成形提供了理论支持。

In order to obtain the transient temperature field of friction stir spot welding,according to the tribological principle,a new combined heat source model is established which is the coupling result of a uniform surface heat source and a double ellipsoid heat source,and the instantaneous changes of the positive pressure of the stirring needle and the material properties are considered. The ABAQUS finite element software was used to simulate the transient changes of temperature field of 2 mm thick 6061-T6 aluminum alloy sheet Friction Stir Spot Welding(FSSW) in three stages,including under pressure,remaining and cooling. The accuracy of the combined heat source model was verified by welding thermal cycle test. The effect of rotation speed on temperature field is studied. The analysis shows that the mechanism of the no phase change of the friction stir welding is the negative feedback adjustment of the temperature through the change of the yield stress of the material. This new heat source model provides theoretical support for studying the instantaneous temperature variation and solder joint forming of FSSW.