Quantitative investigation of gas flow, powder-gas interaction, and powder behavior under different ambient pressure levels in laser powder bed fusion
Quantitative investigation of gas flow, powder-gas interaction, and powder behavior under different ambient pressure levels in laser powder bed fusion
复制标题
DOI：
10.1016/j.ijmachtools.2021.103797
复制
发表时间：
2021-09-13
影响因子：
14
通讯作者：
Tan, Wenda
中科院分区：
文献类型：
--
作者：
Li, Xuxiao;Guo, Qilin;Tan, Wenda
激光粉末床熔融（LPBF）工艺中的粉末运动会导致成品中的缺陷和可变性问题。据报道，环境压力对粉末运动有显着的影响，但环境压力对气体流动，粉末-气体相互作用和粉末行为的物理效应没有定量的理解。在这项工作中，我们已经开发了第一个三维多物理场模型LPBF模拟熔池动力学，凹陷区的演变，气流结构，粉末运动在一个完全耦合的方式。该模型使第一个定量调查的气体流动，粉末-气体相互作用，并在LPBF粉末行为与不同的环境压力水平，所有这些都是难以测量的实验。模拟结果表明，一致的气体流动结构的所有不同的压力水平，但气体流动参数（温度，速度，雷诺数，和努森数）随环境压力的变化显着。四个粉末-气体相互作用模式被定义为颗粒周围的气体流动和颗粒上的气体诱导力，和相互作用模式，单独或集体，控制每个颗粒的运动。随着环境压力和气流参数的变化，四种模式对粉末运动的重要性不同，粉末的行为（温度、力、速度和喷射角）也不同。根据建模结果提出了一种新的粉末运动抑制策略。
The powder motion in laser powder bed fusion (LPBF) processes causes defect and variability issues in the built products. It has been reported that the ambient pressure has a significant influence on the powder motion, but the physical effects of the ambient pressure on the gas flow, powder-gas interaction, and powder behavior are not quantitatively understood. In this work, we have developed the first three-dimensional multiphysics model for LPBF to simulate the molten pool dynamics, depression zone evolution, gas flow structure, and powder motion in a fully coupled manner. The model enables the first quantitative investigation of the gas flow, powder-gas interaction, and powder behavior in LPBF with different ambient pressure levels, all of which are difficult to measure by experiments. The simulation results show a consistent gas flow structure for all different pressure levels, but the gas flow parameters (temperature, velocity, Reynolds number, and Knudsen number) vary significantly with the ambient pressure. Four powder-gas interaction modes are defined by the gas flow around the particle and the gas-induced forces on the particle, and the interaction modes, individually or collectively, control the motion of each particle. With the changes in the ambient pressure and the gas flow parameters, the significance of the four modes to the powder motion varies, and the powder behavior (temperature, force, velocity, and ejection angle) becomes different. A new strategy is proposed to mitigate the powder motion based on the modeling results.