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李雯, 刘其鹏, 高月华, 楚锡华, 张昭, 王振军. 基于离散元法的SLM刮刀倾角对粉末铺展行为的影响研究. 力学学报, 2024, 56(3): 773-783. DOI: 10.6052/0459-1879-23-462
引用本文: 李雯, 刘其鹏, 高月华, 楚锡华, 张昭, 王振军. 基于离散元法的SLM刮刀倾角对粉末铺展行为的影响研究. 力学学报, 2024, 56(3): 773-783. DOI: 10.6052/0459-1879-23-462
Li Wen, Liu Qipeng, Gao Yuehua, Chu Xihua, Zhang Zhao, Wang Zhenjun. Investigation into SLM blade inclination effect on powder spreading behavior based on discrete element method. Chinese Journal of Theoretical and Applied Mechanics, 2024, 56(3): 773-783. DOI: 10.6052/0459-1879-23-462
Citation: Li Wen, Liu Qipeng, Gao Yuehua, Chu Xihua, Zhang Zhao, Wang Zhenjun. Investigation into SLM blade inclination effect on powder spreading behavior based on discrete element method. Chinese Journal of Theoretical and Applied Mechanics, 2024, 56(3): 773-783. DOI: 10.6052/0459-1879-23-462

基于离散元法的SLM刮刀倾角对粉末铺展行为的影响研究

INVESTIGATION INTO SLM BLADE INCLINATION EFFECT ON POWDER SPREADING BEHAVIOR BASED ON DISCRETE ELEMENT METHOD

  • 摘要: 刮刀倾角对选区激光熔化过程粉末铺展行为有重要影响. 基于离散元法建立铺粉数值模型, 对不同刮刀倾角的铺粉过程及粉层质量进行模拟研究. 针对不同的刮刀倾角, 提出一个量化指标对粉层铺展的致密度和均匀性进行综合评估, 获得刮刀倾角对粉层质量的影响规律. 根据颗粒分布及运动特征将粉堆颗粒体系划分为底层区、斜坡区、刮刀影响区和内部区4个区域. 针对各区域进行铺粉过程动力学机理的深入研究, 包括颗粒运动轨迹和速度场、刮刀前方剪切带、颗粒间力链分布及演化等. 研究发现: 刮刀倾角小于0时, 颗粒体系难以形成完整的环流运动, 剪切带较小, 流向沉积层的颗粒较少, 颗粒间强力链较少, 刮刀间隙前方易形成力拱导致颗粒堵塞, 进而形成空斑使得沉积层的致密度和均匀性较低. 刮刀倾角大于0时, 颗粒体系的环流运动较充分, 剪切带较大, 流向沉积层的颗粒增多, 随倾角增大强力链增多, 刮刀压实作用增强, 有利于沉积层致密度和均匀性的提高. 本研究为优化工艺参数、提高粉层沉积质量提供了理论基础.

     

    Abstract: The blade inclination plays a significant role on the powder spreading behavior during the selective laser melting process. In this paper, a discrete element numerical model is established to investigate the powder spreading process and quality with different blade inclination angles. A quantitative indicator was proposed for different blade inclination angles to comprehensively evaluate the packing density and uniformity of the powder layer and the influence law of blade inclination on deposition quality is obtained. Based on the particle distribution and motion characteristics, the particle heap is divided into four zones including bottom layer zone, slope zone, blade influence zone, and internal zone. The powder spreading dynamic mechanism is comprehensively analyzed for the four regions, including particle trajectories and velocity fields, the shear band in front of the blade, and the distribution and evolution of inter-particle forces. It is found that when the inclination angle is less than zero, it is difficult for the particle heap to form a complete circulating flow, the shear band is relatively small, fewer particles flow towards the deposition layer, the packing density of powder layer decreases, fewer strong force chains between particles form, and force arches are easily formed in front of the blade gap, leading to particle jamming and the formation of voids. Therefore, the density and uniformity of deposition layer are poor. When the angle is greater than zero, the circulating movement of particle system is adequate, the shear band is larger, and more particles flow to the deposition layer, and the packing density of powder layer increases. As the inclination angle increases, the strong force chains increase, and the compaction effect of the blade is enhanced, which is beneficial for improving the density and uniformity of the deposition layer. This study provides a theoretical reference for the process parameter optimization and powder bed quality improvement.

     

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