They used the model for determination of melt pool size in single metallic

They used the model for determination of melt pool

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penetration Depth of laser was taken into account in defining the heat source. They used the model for determination of melt pool size in single metallic powder layer (material stainless steel 316L). They have shown that modelling results agree with the experimental data. The scanning pattern (striping format) is showing Figure2.3.6.6. Figure 2-22 (a) Finite element model (b) Pattern of scanning (Foroozmehr et al) (2016) ) Figure 2-23 Selective laser sintering process variables (L. Criales et al., 2016) The parameters of selective laser sintering are shown in Figure.2.3.6.7. Input parameters are essential to all models of the powder bed fusion and directed energy deposition process. Input parameters always contain a heat source. A moving heat source presents
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- 64 - laser with powder and profile shape. Besides, input parameters also contain the condition of powder (the geometry of powder, powder ‘s boundary conditions and powder‘s thermos characteristics). Besides the finite element method-based models have been mentioned. Several researchers have developed or invented other new models by using finite element method to simulate the process of sintering, such as Heat transfer, Material deposition/melt pool, Mechanical properties, Phase change. Some researchers have developed a number of models, which are used to simulate heating, solidification of materials, and melting during the process of powder bed fusion process (Mahesh Mani et al., 2015). According to Kolossov et al. (2003), the 3D heat transfer model of selective laser sintering (SLS) was used for temperature, specific heat, phase transformations, and powder thermal conductivity. This 3D thermal model is a numerical model. Based on this model, the formation of printed part and the temperature evolution can be simulated (Kolossov et al., 2003). The powder is treated as a continuous material in this model. When the heat source arrived at a certain area, the temperature distribution can be obtained. Kolossov et al. (2003) also have performed physical experiments and carried out temperature validation measurements with the help of an infra-red camera. However, they ignored the changes in density. Patil and Yadava (2007) have developed a finite element model for predicting the temperature filed in single powder birth of titanium during metal laser sintering process. They studied the effect of laser processing parameters such as laser powder, beam diameter, laser on-time, laser off- time, and hatch spacing in temperature distribution of a single metallic powder layer by using the finite element method-based model. The present teat transfer model can be used to analysis the effect of the bed density, Gaussian heat flux distribution of the heat source and the thermal conductivity (Patil and Yadava, 2007).
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- 65 - Similar 3D FEM modelling has also been done by Dong et al (2009) and Kolossov et al (2004). Toyserkani et al (2004) used 3D FEM to study the effects of laser pulse shaping on the sintering process. Hu and Kovacevic (2003) did 3D FEM modelling to explore thermal behavior of molten pool. Fan and Liou (2012) summarized numerical modelling of heat transfer and molten pool fluid dynamics in AM of titanium. Liu et al (2012) did a 3D FEM modelling of thermal evolution in SLS. What ‘s interesting is that it was done at
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  • Fall '15
  • Selective laser sintering, Particle size distribution, sintering, Additive manufacturing

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