6061-T6铝合金搅拌摩擦焊温度场的数值模型和参数影响分析
Numerical Model and Influence Analysis of Parameters for Temperature Field in Friction Stir Welding of 6061-T6 Aluminum Alloy

针对带圆柱搅拌针的搅拌头，推导了一种搅拌摩擦焊热源模型的一般表达式，按照滑动摩擦、粘着摩擦和混合滑动摩擦与粘着摩擦3种机制计算其中的摩擦应力，得到3种热源模型。采用ABAQUS软件，通过子程序实现热源模型并进行加载，建立了12.7 mm厚6061-T6铝合金板的搅拌摩擦焊温度场数值模型。数值模拟结果与实验结果的对比表明：基于粘着摩擦和混合滑动摩擦与粘着摩擦的模型能较好地预测温度场，两者给出的焊接稳态温度场基本一致，而基于滑动摩擦的模型预测的温度场偏高。通过改变模型参数的取值，系统地研究了边界条件、预热时间、焊接参数、搅拌头结构尺寸对温度场、产热功率和搅拌头所受力矩的影响，得到一系列规律和指标。
A general expression is derived to describe heat generation in friction stir welding (FSW) by a tool with cylindrical pin. Three heat source models are obtained by calculating frictional stresses in the expression according to sling friction, sticking friction and the combination of them, respectively. In ABAQUS, these heat source models are implemented in subroutines to apply loads, and a model for simulating the temperature field of FSW of 12.7 mm-thick 6061-T6 aluminum alloy plate is established. The numerical analysis results are compared with the experimental. It is found that heat source models based on sticking friction and combination of sliding and sticking friction can well predict temperature field and nearly produces the same results for steady state of welding, while the model based on sliding friction gives higher temperature than the experimental. By varying relevant parameters of the model, influences of boundary conditions, preheating time, welding parameters and structural parameters of the tool are systematically studied. A number of rules and indices are obtained