Global local modeling of melt pool dynamics and bead formation in laser bed powder fusion additive manufacturing using a multi-physics thermo-fluid simulation
Global local modeling of melt pool dynamics and bead formation in laser bed powder fusion additive manufacturing using a multi-physics thermo-fluid simulation
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DOI：
10.1007/s40964-022-00302-w
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发表时间：
2022-04-29
影响因子：
--
通讯作者：
Ladani, Leila
中科院分区：
文献类型：
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作者：
Ahsan, Faiyaz;Razmi, Jafar;Ladani, Leila
了解激光粉末床熔融（LPBF）增材制造的物理机制可以通过计算建模受益匪浅。LPBF使用激光热源熔化多层粉末颗粒，并根据CAD设计制造零件。本工作旨在评估Marangoni流，浮力和反冲压力的影响，以模拟熔池周围的流体流动与非高斯激光束，以模拟激光和粉末床之间的相互作用。据观察，由于表面张力梯度引起的两侧Marangoni对流，速度分布在最高温度点的两侧显示出两个峰。还基于佩克莱数、努塞尔数和马兰戈尼数进行了尺寸分析，以确定各种激光功率/扫描速度组合下的热传输模式。由于流体的剧烈流动和熔融区域周围的反冲压力，对流热流是较高能量输入下的主要传热形式，这也会产生与诸如孔隙等缺陷相关的小孔效应。计算模型也通过比较凝固珠几何形状与实验数据进行了验证。
Understanding the physical mechanism of laser-powder bed fusion (LPBF) additive manufacturing can benefit significantly through computational modeling. LPBF uses a laser heat source to melt a number of layer of powder particles and manufactures a part based on the CAD design. This work aims to assess the impact of Marangoni flow, buoyancy and recoil pressure to simulate the fluid flow around melt pool with a non-Gaussian laser beam to simulate the interaction between laser and powder bed. It was observed that velocity profile shows two peaks on either side of the highest temperature point owing to Marangoni convection on both sides due to gradient in surface tension. Dimensional analysis was also conducted based on Peclet number, Nusselt number and Marangoni number to determine the mode of heat transport at various laser power/scan speed combinations. Convective heat flow is the dominant form of heat transfer at higher energy input due to violent flow of the fluid and recoil pressure around the molten region, which can also create keyhole effect associated with defects such as porosities. The computational model was also validated by comparing solidified bead geometry with experimental data.