An open source two-dimensional (2D) thermal finite element (FE) model of the Directed Energy Deposition (DED) process is developed using the Python-based FEniCS framework. The model incrementally deposits material ahead of the laser focus point according to the geometry of the part. The laser heat energy is supplied by a Gaussian-distributed heat source while the phase change is represented by increased heat capacity around the solidus-liquidus temperature range. Experimental validation of the numerical model is performed by matching with the melt pool temperature measurements taken by a dual wavelength pyrometer during the build process of a box-shaped Ti--6Al--4V part with large geometrical voids. Effects of large geometrical voids on the melt pool shape and maximum melt pool temperature are examined. Both the numerical and experimental data show an increase in the melt pool size and temperature during deposition above large voids. The trailing edge of the melt pool's temperature profile obtained using the developed numerical model closely matches pyrometer measurements.

中文翻译：

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定向能量沉积的二维热有限元模型：匹配熔池温度曲线与高温计测量

使用基于 Python 的 FEniCS 框架开发了定向能量沉积 (DED) 过程的开源二维 (2D) 热有限元 (FE) 模型。该模型根据零件的几何形状在激光焦点前逐渐沉积材料。激光热能由高斯分布的热源提供，而相变表现为在固相-液相线温度范围内增加的热容量。数值模型的实验验证是通过与双波长高温计在具有大几何空隙的盒形 Ti--6Al--4V 零件的构建过程中进行的熔池温度测量相匹配来进行的。检查了大几何空隙对熔池形状和最大熔池温度的影响。数值和实验数据均显示在大空隙上方沉积期间熔池尺寸和温度增加。使用开发的数值模型获得的熔池温度曲线的后缘与高温计测量结果非常匹配。