A conservative level set method on unstructured meshes for modeling multiphase thermo-fluid flow in additive manufacturing processes
A conservative level set method on unstructured meshes for modeling multiphase thermo-fluid flow in additive manufacturing processes
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DOI：
10.1016/j.cma.2020.113348
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发表时间：
2020-12-01
影响因子：
7.2
通讯作者：
Wagner, Gregory J.
中科院分区：
文献类型：
--
作者：
Lin, Stephen;Gan, Zhengtao;Wagner, Gregory J.
增材制造 (AM) 是一种新兴技术，它使用局部热源将沉积的粉末材料逐层熔合在一起，以创建任意复杂的几何形状。这项技术本质上是一个多物理场问题，涉及流体流动、传热、自由表面、激光-材料相互作用以及包括固体、液体和气体在内的材料相的同时演化。多物理场和多相模型通常用于通过高保真度模拟来了解驱动增材制造工艺的主要物理场，解析单个粉末在熔化到基材上时的情况。然而，这些类型的高保真度模型不适用于模拟定向能量沉积（DED）过程，其中粉末通过喷嘴通过环境蒸汽输送到基材上，然后熔化。本文提出了一种用于模拟 DED 过程的新型多相热流体配方。漫射水平集公式与纳维-斯托克斯、能量守恒和辐射传输方程相结合，使我们能够对复杂的自由表面、流体流动、热和激光相互作用演化进行建模。此外，我们的配方使我们能够解析增材制造工艺过程中的蒸汽流场及其对沉积材料的影响。通过与文献解决方案和实验基准进行比较来评估我们提出的方法的准确性。然后，我们提出的公式用于对简单的 DED 过程进行建模，使我们能够可视化粉末颗粒夹带进入熔池的情况。该过程阐明了可将粉末驱入熔池的主要物理力及其对 DED 过程中熔池演变的影响。 (C) 2020 Elsevier B.V. 保留所有权利。
Additive manufacturing (AM) is an emerging technology that fuses deposited powder materials together layer-by-layer using a localized heat source to create an arbitrarily complex geometry. This technology is an inherently multiphysics problem, involving the simultaneous evolution of fluid flow, heat transfer, free surface, laser-material interaction and material phases including solid, liquid and gas. Multiphysics and multiphase models are typically used to understand the dominant physics driving AM processes through high fidelity simulations resolving the individual powders as they melt onto the substrate. However, these types of high fidelity models have not been applicable to modeling directed energy deposition (DED) process, where powders are delivered through the ambient vapor onto the substrate by a nozzle and subsequently fused. This paper presents a novel multiphase thermo-fluid formulation for modeling DED processes. A diffuse level set formulation coupled with the Navier-Stokes, energy conservation and radiative transport equation allows us to model complex free surface, fluid flow, thermal and laser interaction evolution. In addition, our formulation enables us to resolve the vapor flow field and its effect on deposited material during AM processes. The accuracy of our proposed method is assessed by comparing with literature solutions and experimental benchmarks. Our proposed formulation is then used to model simple DED processes that enable us to visualize the entrainment of powder particles into the melt pool. This process elucidates the dominant physical forces that can drive powders into the melt pool as well as their effect on the melt pool evolution within DED processes. (C) 2020 Elsevier B.V. All rights reserved.