The finite-element （FE） model and the Rosenthal equation are used to study the thermal and microstructural phenomena in the laser powder-bed fusion of lnconel 718. A primary aim is to comprehend the advantages and d...The finite-element （FE） model and the Rosenthal equation are used to study the thermal and microstructural phenomena in the laser powder-bed fusion of lnconel 718. A primary aim is to comprehend the advantages and disadvantages of the Rosenthal equation （which provides an analytical alternative to FE analysis）, and to investigate the influence of underlying assumptions on estimated results. Various physical characteristics are compared among the FE model, Rosenthal equation, and experiments. The predicted melt pool shapes compared with reported experimental results from the literature show that both the FE model and the analytical （Rosenthal） equation provide a reasonably accurate estimation. At high heat input, under conditions leading to keyholing, the reported melt width is narrower than predicted by the analytical equation. Moreover, a sensitivity analysis based on choices of the absorptivity is performed, which shows that the Rosenthal approach is more sensitive to absorptivity, compared with the FE approach. The primary reason could be the effect of radiative and convective losses, which are assumed to be negligible in the Rosenthal equation. In addition, both methods predict a columnar solidification microstructure, which agrees well with experimental reports, and the primary dendrite arm spacing （PDAS） predicted with the two approaches is comparable with measurements.展开更多
The phenomena of a single bubble boiling process are studied with numerical modeling.The mass,momentum,energy and level set equations are solved using COMSOL and temperature field in time are analyzed,and reasonable r...The phenomena of a single bubble boiling process are studied with numerical modeling.The mass,momentum,energy and level set equations are solved using COMSOL and temperature field in time are analyzed,and reasonable results are obtained.The numeral model is validated by the empirical equation of Fritz and could be used for various applications.展开更多
基金support from the Royal Thai Government and the Bertucci Graduate Fellowship for this research. P. Chris Pistoriussupport from Early Stage Innovations under National Aeronautics and Space Administration (NASA)’s Space Technology Research Grants Program (NNX 17AD03G)
文摘The finite-element （FE） model and the Rosenthal equation are used to study the thermal and microstructural phenomena in the laser powder-bed fusion of lnconel 718. A primary aim is to comprehend the advantages and disadvantages of the Rosenthal equation （which provides an analytical alternative to FE analysis）, and to investigate the influence of underlying assumptions on estimated results. Various physical characteristics are compared among the FE model, Rosenthal equation, and experiments. The predicted melt pool shapes compared with reported experimental results from the literature show that both the FE model and the analytical （Rosenthal） equation provide a reasonably accurate estimation. At high heat input, under conditions leading to keyholing, the reported melt width is narrower than predicted by the analytical equation. Moreover, a sensitivity analysis based on choices of the absorptivity is performed, which shows that the Rosenthal approach is more sensitive to absorptivity, compared with the FE approach. The primary reason could be the effect of radiative and convective losses, which are assumed to be negligible in the Rosenthal equation. In addition, both methods predict a columnar solidification microstructure, which agrees well with experimental reports, and the primary dendrite arm spacing （PDAS） predicted with the two approaches is comparable with measurements.
文摘The phenomena of a single bubble boiling process are studied with numerical modeling.The mass,momentum,energy and level set equations are solved using COMSOL and temperature field in time are analyzed,and reasonable results are obtained.The numeral model is validated by the empirical equation of Fritz and could be used for various applications.
