差速双轴肩搅拌摩擦焊温度场、应变场及流动特性数值模拟

Numerical simulation of temperature field,strain field and flow characteristics of differential bobbin tool friction stir welding

为研究差速双轴肩搅拌摩擦焊接过程中温度特性、应变分布与材料流动规律,基于DEFORM-3D软件,针对5 mm厚AZ91镁合金板材建立全热-力耦合模型。进行差速双轴肩搅拌摩擦焊数值仿真,分析与双轴肩搅拌摩擦焊的异同。结果表明,厚度方向的温度场,差速双轴肩搅拌摩擦焊上轴肩影响区的温度低于下轴肩影响区,呈近似“花瓶状”分布;水平方向上,后退侧温度高于前进侧;而在应变场分布上,差速双轴肩搅拌摩擦焊前进侧等效应变更高,与温度场分布规律相反;在材料流动特性方面,差速双轴肩搅拌摩擦焊前进侧材料流动性更活跃;沿厚度方向,差速双轴肩搅拌摩擦焊转速较高一侧的轴肩影响区更大,中部材料偏向轴肩转速高的一侧移动。

In order to study the temperature characteristics,strain distribution and material flow law during differential bobbin tool friction stir welding(DBT-FSW),an all-heat-force coupling model is established for the 5 mm thick AZ91 magnesium alloy plate based on deform-3D software to conduct numerical simulation of DBT-FSW and analyze the similarities and differences with bobbin tool friction stir welding.The results show that the temperature field of DBT-FSW in the direction of thickness shows an approximate"vase"distribution,while the temperature in the affected area of the upper shoulder is lower than that of the lower shoulder.In the horizontal direction,the temperature of DBT-FSW is higher on the retreating side than on the advancing side.As for the strain field distribution,the equivalent strain on the advancing side is higher,which is contrary to the law of temperature field distribution.In terms of material flow characteristics,the advancing side of DBT-FSW has more active material flow.In the direction of thickness of DBT-FSW,the influence area of the shaft shoulder on the side with higher rotation speed is larger,and the material in the middle part moves towards the side with higher rotation speed.