【摘要】 将搅拌摩擦焊接过程中材料的流动看作是层流、粘性、非牛顿流体绕过旋转的搅拌头探针,并基于流体力学理论,建立了三维搅拌摩擦焊缝金属塑性流动的数值分析模型。提出了一种联合粘度场、速度场对焊接区域进行划分的方法:搅拌头周围的η0(材料粘度值)内易流动区域对应于焊核,η0外围与η1粘度带之间的区域对应于TMAZ区。三维模拟中材料的垂直方向流动与“标记嵌入技术”流变可视化试验结果吻合较好:靠近探针的区域内,回撤边中下部的材料向上运动,前进边中下部材料向下运动。焊接速度过高,搅拌头轴肩与探针过渡处的易流动区容易发生材料的分离运动,实际焊接中在此处容易产生空洞缺陷。更多还原

【Abstract】 A three-dimensional friction stir welding(FSW) process model is developed based on fluid mechanics. The material transport in the welding process is regarded as a laminar, viscous and non-Newtonian liquid flows past a rotating pin. A criterion to divide the weld zone is given on the basis of cooperation of velocity field and viscosity field. That is, theη0-easy-flow-zone existed near the tool pin is corresponded to the weld nugget zone, the area between theη0-easy-flow-zone andη1-viscosity-band is corresponding to TMAZ. Results of the simulation show that the material in the middle part of the weld flows vertically. In the retreating side the material is pushed up and in the advancing side the material is pushed down. Material flow visualization experiments of marker insert technology are used to validate the simulated results. The experimental images can agree well with the simulated results. Under higher welding speeds, material separated motion can be seen in the shoulder-pin transition part, and an actual welding defect of void is observed at the same position in the weld seam.更多还原