激光快速成形金属薄壁零件的三维瞬态温度场数值模拟

Numerical simulation of 3 D transient temperature field in thin-wall metal parts fabricated by laser direct deposition

利用ANSYS有限元软件中的'生死单元'技术,建立了与激光快速成形过程一致的三维瞬态薄壁零件温度场计算模型。通过该计算模型,可以掌握成形过程中薄壁零件温度场随时间的变化规律。计算结果表明,金属薄壁零件中,与x方向温度梯度相比,y方向温度梯度占绝对优势,因此在薄壁零件冷却过程中,热量散失主要方向为y方向。激光功率越高,y方向温度梯度也越大,因此形成的枝晶组织就越细长。

By using 'birth and death' element technology of the ANSYS software, the FEM model simulating the real process of the metal thin wall fabricated by laser direct deposition was established to calculate the 3 D transient temperature field in the thinwall metal part. The temperature field at different time in the thinwall metal part can be understood by the FEM model. The calculated results show that, the temperature gradient along y direction within the metal thin wall is absolutely predominant compared with the temperature gradient along x direction, thus heat dissipates mainly along y direction during deposition. The higher the laser power, the greater the temperature gradient along y direction of thinwall metal part, therefore the finer the dendrites.