Many additive manufacturing (AM) technologies rely on powder feedstock, which is fused to form the final part either by melting or by chemical binding with subsequent sintering. In both cases, process stability and resulting part quality depend on dynamic interactions between powder particles and a fluid phase, i.e., molten metal or liquid binder. The present work proposes a versatile computational modeling framework for simulating such coupled microfluid-powder dynamics problems involving thermo-capillary flow and reversible phase transitions. In particular, a liquid and a gas phase are interacting with a solid phase that consists of a substrate and mobile powder particles while simultaneously considering temperature-dependent surface tension and wetting effects. In case of laser-metal interactions, the effect of rapid evaporation is incorporated through additional mechanical and thermal interface fluxes. All phase domains are spatially discretized using smoothed particle hydrodynamics. The method's Lagrangian nature is beneficial in the context of dynamically changing interface topologies. Special care is taken in the formulation of phase transitions, which is crucial for the robustness of the computational scheme. While the underlying model equations are of a very general nature, the proposed framework is especially suitable for the mesoscale modeling of various AM processes. To this end, the generality and robustness of the computational modeling framework is demonstrated by several application-motivated examples representing the specific AM processes binder jetting, material jetting, directed energy deposition, and powder bed fusion. Among others, it is shown how the dynamic impact of droplets in binder jetting or the evaporation-induced recoil pressure in powder bed fusion leads to powder motion, distortion of the powder packing structure, and powder particle ejection.
翻译:许多添加剂制造(AM)技术依靠粉末原料,粉末原料通过熔化或化学结合和随后的交接而成最后部分,在这两种情况下,过程稳定性和由此产生的部分质量取决于粉末粒子和液体相位(即熔化金属或液体粘合器)之间的动态互动。目前的工作提出一个多功能的计算模型框架,用于模拟这种结合的微流和可逆的相粉剂动态问题。特别是,液态和气相与一个由基底和移动粉粒组成的固态阶段相互作用,同时考虑温度依赖的表面紧张和湿效应。在激光-金属相位和液体相位的相互作用中,快速蒸发的效果是通过额外的机械和热接口通量。所有阶段都使用平滑的粒子流体流体流和可逆相向流体变化。在动态直流的界面结构变化中,特别注意液体和气压转变的形成过程,这对温度调和移动粉质的温度变化至关重要,而对温度的温度调和运动其他的温度调和湿性作用,在计算方法中,对于计算结果的稳定性结构的稳定性结构结构中,特别的稳定性的稳定性分析显示,在一般的稳定性结构结构中,其底压结构中,其底压结构结构结构结构是显示,在一般的底压结构结构结构中显示的伸缩压是。