基于生死单元的激光熔覆温度场数值模拟

Numerical simulation on temperature field of laser cladding based on birth-death element method

计算了不同激光功率条件下粉末粒子到达基体前的温升情况,并将粉末粒子到达基体前的温度作为初始条件,采用生死单元法对单道和多道激光熔覆温度场进行了研究.利用熔池尺寸和形貌,验证了模型的可靠性.结果表明,粉末粒子温升和激光功率呈线性关系,单道熔覆层的温度变化呈一个锯齿状,升温过程近似呈直线上升,降温曲线近似呈双曲线的一支,而多道熔覆过程中,温度场呈后拖的偏椭圆状.节点上的热循环经过逐渐增大的峰值,峰值温度最终趋于稳态.

The temperature increase of powder particles was computed with different laser power as the main parameter,and it was used as an initial condition in analyzing temperature field of both single and multiple laser cladding with birth-death element method.The reliability of the model was verified by the dimension and morphology of the molten pool.The temperature of particles increases linearly with laser power being increased.The temperature curve of single clad shows a sawtooth type,in which the temperature increases linearly and decreases as half of a hyperbolic curve.The temperature field of multiple cladding shows a backward dragged ellipse.The thermal cycle of every node goes though some several incremental peaks and tends to a stable state in the end.