激光快速成形过程中粉末与熔池交互作用的数值模拟

NUMERICAL SIMULATION OF INTERACTION BETWEEN METAL POWDER AND MELTING POOL DURING LASER RAPID FORMING

建立了描述激光快速成形过程中气／粉两相流送粉、粉末与熔池交互作用及激光熔覆成形温度场的联合模型．采用有限单元生死技术模拟了熔池形成和自由界面形状演化及熔覆层的沉积过程．根据界面温度与粉末粒子动量损失状况模拟了熔池对粒子的捕捉以及工件对粉末的反射,并采用Lagrangian粒子追踪模型实现了对粉末颗粒的跟踪．在此基础上,模拟了激光快速成形过程中316L不锈钢粉末,激光与熔池的交互作用过程．计算结果与实验结果吻合．

During LRF, the melting pool free surface serves as a moving window of laser power and powder mass input and a dynamic boundary of the LRF continuous growth domain, so the interaction between laser, powder and melting pool free surface is the basic problem that should be coped with in LRF process. The melting pool transient temperature field and gas/powder two phase fluid field numerical model are established. Using finite element birth and death technology, the growth of cladding layers and shape of melting pool free surface are simulated, and using Lagrangian particle tracking model and momentum loss （parallel and perpendicular） option, the interaction between melting pool free surface and powder such as capture and reflect was simulated. At last, the interaction between 316L stainless steel powder, laser and melting pool free surface was calculated, and the numerical result is in agreement with that of the experiment.