扫描方式对激光金属沉积成形过程热应力的影响

EFFECTS OF SCANNING METHODS ON THERMAL STRESS DURING LASER METAL DEPOSITION SHAPING

为改善金属试样的成形质量,降低沉积过程的热应力,研究不同扫描方式下激光金属沉积成形过程中热应力的动态分布规律具有非常重要的意义。根据有限元中的'单元生死'技术,通过ANSYS参数化设计语言(ANSYS parametric design language,APDL)编程研究了沿长边平行往复、沿短边平行往复以及层间正交变向平行往复等填充扫描方式对整个成形过程热应力的影响,详细探讨了各种扫描方式下Von Mises热应力、x方向热应力、y方向热应力以及z方向热应力的动态分布规律,并分析热应力产生和分布的原因。在与模拟过程相同的条件下,实际成形试验所得结果与模拟结果吻合较好。

In order to improve the quality of samples and decrease the stress during process, it is of great importance to study the dynamic distribution regularities of thermal stress during laser metal deposition shaping （LMDS） process. According to the ＂element life and death＂ technique of finite element method （FEM）, detailed three-dimensional multi-track and multi-layer numerical simulations for LMDS are conducted by using ANSYS parametric design language （APDL）. In those simulations, the effects of long edge, short edge and direction orthogonal changing in different layers reciprocating scanning to thermal stress during whole metal cladding process are studied, the dynamic distributions of Von Mises, x-directional, y-directional and z-directional thermal stresses under different scanning way are researched, the generation and distribution regularities of thermal stress are also discussed. Using the same process parameters, the simulation results show good agreement with the features of samples which fabricated by LMDS.