双轴肩搅拌摩擦焊接头温度场和流场数值模拟分析

目的 研究铝合金双轴肩搅拌摩擦焊接头温度场和流场规律。方法 以2024铝合金为研究对象，借助FLUENT软件，综合考虑了温度和应变速率对铝合金粘度的影响，采用修正的本构模型，分析了典型双轴肩搅拌摩擦焊接条件下接头温度和速度特征。结果 搅拌头边缘，应变速率较大，接近1000 s-1；温度场呈现出对称的哑铃状分布，最高温度为751 K，达到2024铝合金熔点的83%；前进侧温度大于后退侧温度，前进侧温度为640 K左右，后退侧为600 K左右；双轴肩摩擦焊材料流动速度大于常规焊，前进侧速度大于后退侧速度，前进侧轴肩作用区域大于后退侧；前进侧轴肩作用区域延伸至板材中间，造成带状不连续缺陷。结论 CFD软件Fluent可以较为准确地分析双轴肩搅拌摩擦焊的温度场和流场，可为搅拌工具的优化提供依据。

Numerical Simulation of Temperature and Fluid Flow Field during Bobbin-Tool FSW

The paper aims to study the rule of temperature field and flow field of the bobbin-tool friction stir welding. With 2024 aluminum alloy as the study object, the effect of temperature and strain rate on viscosity was considered by virtue of FLUENT software. A modified constitutive model was used to analyze the typical temperature and velocity characteristics of bobbin-tool shoulder friction stir welding. The results showed that the strain rate was the large at the edge of the tool, which was close to 1000 s-1. The temperature field showed a symmetrical dumbbell-shaped distribution with a maximum temperature of 751 K, which was 83% of the melting point of the 2024 aluminum alloy. The temperature on the advancing side was greater than that of the retreating side. The advancing side temperature was about 640 K, and that of the retreating side was about 600 K. The speed of bobbin-tool friction stir welding was greater than that of conventional welding. The speed of the advancing side was greater than that of the retreating side. The shoulder affected zone of the advancing side was larger than that of the backward side. The shoulder action area of the advancing side extended to the middle of the sheet, causing a Band Pattern defect. CFD software-Fluent can accurately analyze the temperature field and flow field of bobbin-tool friction stir welding. It can provide basis for optimization of stirring tools.