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Papers by Andre Giordimaina
John Wiley & Sons, Inc. eBooks, Feb 3, 2016
In order to increase the powder bed production rates, the laser power and diameter are increased ... more In order to increase the powder bed production rates, the laser power and diameter are increased enabling faster scanning, thicker powder layers and wider hatches. These parameters however interact in a very complex manner: For example increasing the laser power may lead to significant evaporation of the molten metal. Increasing the scan speed may lead to reduced melting and lack of fusion of the powder particles. Combining higher scanning speeds with increased layer thickness enhances lack of fusion even more. Larger beam diameters reduce the energy density and hence impose limitations to scan speeds. Physics based modelling has the potential to shed light into how these competing phenomena interact and can accelerate fine tuning build parameters to achieve design goals. Models resolving the heat source powder interaction and describing the melt pool and solidification processes could not be formally validated using experimental data due to the extreme severity of the processing environment. In an effort to verify models describing melt pool behavior the results of two different algorithms are compared: Lattice Boltzmann and Finite Volume Computational Fluid Dynamics. Both codes were developed separately by two different and independent teams. A reference benchmark is defined with corresponding operation conditions. The physical assumptions are aligned as far as possible. The melt pool characteristics and the thermal cycles are compared.
One of the most important ingredients in a numerical model of Additive Manufacturing (AM) is a he... more One of the most important ingredients in a numerical model of Additive Manufacturing (AM) is a heat transfer model. On its own this is challenging enough as conductive, convective and radiative heat transfer mechanisms are all important, coupled with liquid/solid phase changes. For metals and alloys the process is also inherently multiscale – a perennial problem in materials science. Furthermore, heat transfer is only the first step to predict different phenomena of interest including metallurgical microstructure, defects and thermal stresses to name a few. This paper briefly touches on several of these areas, all of which merit concerted effort by the modelling community.
TMS 2016 145th Annual Meeting & Exhibition, 2016
In order to increase the powder bed production rates, the laser power and diameter are increased ... more In order to increase the powder bed production rates, the laser power and diameter are increased enabling faster scanning, thicker powder layers and wider hatches. These parameters however interact in a very complex manner: For example increasing the laser power may lead to significant evaporation of the molten metal. Increasing the scan speed may lead to reduced melting and lack of fusion of the powder particles. Combining higher scanning speeds with increased layer thickness enhances lack of fusion even more. Larger beam diameters reduce the energy density and hence impose limitations to scan speeds. Physics based modelling has the potential to shed light into how these competing phenomena interact and can accelerate fine tuning build parameters to achieve design goals. Models resolving the heat source powder interaction and describing the melt pool and solidification processes could not be formally validated using experimental data due to the extreme severity of the processing environment. In an effort to verify models describing melt pool behavior the results of two different algorithms are compared: Lattice Boltzmann and Finite Volume Computational Fluid Dynamics. Both codes were developed separately by two different and independent teams. A reference benchmark is defined with corresponding operation conditions. The physical assumptions are aligned as far as possible. The melt pool characteristics and the thermal cycles are compared.
John Wiley & Sons, Inc. eBooks, Feb 3, 2016
In order to increase the powder bed production rates, the laser power and diameter are increased ... more In order to increase the powder bed production rates, the laser power and diameter are increased enabling faster scanning, thicker powder layers and wider hatches. These parameters however interact in a very complex manner: For example increasing the laser power may lead to significant evaporation of the molten metal. Increasing the scan speed may lead to reduced melting and lack of fusion of the powder particles. Combining higher scanning speeds with increased layer thickness enhances lack of fusion even more. Larger beam diameters reduce the energy density and hence impose limitations to scan speeds. Physics based modelling has the potential to shed light into how these competing phenomena interact and can accelerate fine tuning build parameters to achieve design goals. Models resolving the heat source powder interaction and describing the melt pool and solidification processes could not be formally validated using experimental data due to the extreme severity of the processing environment. In an effort to verify models describing melt pool behavior the results of two different algorithms are compared: Lattice Boltzmann and Finite Volume Computational Fluid Dynamics. Both codes were developed separately by two different and independent teams. A reference benchmark is defined with corresponding operation conditions. The physical assumptions are aligned as far as possible. The melt pool characteristics and the thermal cycles are compared.
One of the most important ingredients in a numerical model of Additive Manufacturing (AM) is a he... more One of the most important ingredients in a numerical model of Additive Manufacturing (AM) is a heat transfer model. On its own this is challenging enough as conductive, convective and radiative heat transfer mechanisms are all important, coupled with liquid/solid phase changes. For metals and alloys the process is also inherently multiscale – a perennial problem in materials science. Furthermore, heat transfer is only the first step to predict different phenomena of interest including metallurgical microstructure, defects and thermal stresses to name a few. This paper briefly touches on several of these areas, all of which merit concerted effort by the modelling community.
TMS 2016 145th Annual Meeting & Exhibition, 2016
In order to increase the powder bed production rates, the laser power and diameter are increased ... more In order to increase the powder bed production rates, the laser power and diameter are increased enabling faster scanning, thicker powder layers and wider hatches. These parameters however interact in a very complex manner: For example increasing the laser power may lead to significant evaporation of the molten metal. Increasing the scan speed may lead to reduced melting and lack of fusion of the powder particles. Combining higher scanning speeds with increased layer thickness enhances lack of fusion even more. Larger beam diameters reduce the energy density and hence impose limitations to scan speeds. Physics based modelling has the potential to shed light into how these competing phenomena interact and can accelerate fine tuning build parameters to achieve design goals. Models resolving the heat source powder interaction and describing the melt pool and solidification processes could not be formally validated using experimental data due to the extreme severity of the processing environment. In an effort to verify models describing melt pool behavior the results of two different algorithms are compared: Lattice Boltzmann and Finite Volume Computational Fluid Dynamics. Both codes were developed separately by two different and independent teams. A reference benchmark is defined with corresponding operation conditions. The physical assumptions are aligned as far as possible. The melt pool characteristics and the thermal cycles are compared.