Fully coupled thermomechanical simulation of friction stir welding of aluminum 6061-T6 alloy T-joint
Fully coupled thermomechanical simulation of friction stir welding of aluminum 6061-T6 alloy T-joint
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DOI：
10.1016/j.jmapro.2019.06.030
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发表时间：
2019-09-01
影响因子：
6.2
通讯作者：
Salloomi, Kareem N.
中科院分区：
文献类型：
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作者：
Salloomi, Kareem N.
目前的研究使用有限元方法对铝 6061-T6 合金 T 型接头类型的搅拌摩擦焊 (FSW) 过程进行全耦合热机械模拟。分析模拟考虑了 FSW 过程的三个步骤，包括：插入、停留和移动阶段。评估了温度历史、通过 FSW 阶段产生的相关应力和应变、工具反作用力以及能量耗散的时间依赖性。为了克服纯拉格朗日和欧拉描述的缺点，使用任意拉格朗日欧拉 (ALE) 公式、自适应网格划分和质量缩放技术来改进搅拌摩擦焊接过程的序列建模。具有非线性摩擦系数的库仑摩擦定律用于模拟工具和 T 形接头配置之间的接触。为了验证数值结果，构建了一个实验装置来执行 T 形接头的 FSW。同时，在前进侧采用嵌入式热电偶测量焊缝附近的温度。整个模拟研究获得的结果表明，温度在 T 型接头宽度上对称分布，并且在切入阶段后，焊接搅拌区的温度轮廓显示出高梯度，呈 V 型形状。数值和实验温度结果之间具有良好的相关性，峰值略有变化。 von-Mises 值的结果表明，在切入过程中，随着工具的前进，最大应力已从蒙皮部分逐渐移至纵梁部分。与后退侧相比，前进侧的塑性应变值较高。此外，热量产生计算表明，摩擦耗散能是产生成功 FSW 所需的大部分热量的原因。
The current study executes a fully coupled thermomechanical simulation of friction stir welding (FSW) process of aluminum 6061-T6 alloy T-joint type using finite element method. The analysis simulation accounts for the three steps of the FSW process which includes: plunging, dwelling, and moving stages. The temperature history, associated stresses and strains generated through the FSW phases, tool reaction force, and time-dependence of the energy dissipation were evaluated. To overcome the shortcomings of purely Lagrangian and Eulerian descriptions, Arbitrary Lagrangian Eulerian (ALE) formulation, adaptive meshing, and the mass scaling were used as techniques to improve sequence modeling of the friction stir welding process. Coulomb's friction law with nonlinear friction coefficient was used to model contact between the tool and T-joint configuration. To verify the numerical results, an experimental setup was constructed to carry out the FSW of a T-joint. Meanwhile, embedded thermocouples were used in the advancing side to measure temperature close to the welding line. The results obtained throughout the simulation study showed that the temperature was symmetrically distributed across the T-joint width, and the temperature contour displayed a high gradient in the weld stirring zone with a V type shape after the plunge stage. Good correlation between numerical and experimental temperature results was obtained with a little shift in the peak value. The results of von-Mises value showed that the maximum stress has been moved from the skin part gradually into the stringer part with the advancement of the tool during plunging. The plastic strain value was higher on the advancing side in comparison with the retreating side. Moreover, the heat generation calculation showed that the frictional dissipation energy was responsible for generating most of the heat needed to obtain a successful FSW.