The Experts below are selected from a list of 165 Experts worldwide ranked by ideXlab platform
Ramesh Raghavendra - One of the best experts on this subject based on the ideXlab platform.
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plastic anisotropy of additively manufactured maraging steel influence of the build orientation and heat treatments
Additive manufacturing, 2019Co-Authors: Barry Mooney, Kyriakos I Kourousis, Ramesh RaghavendraAbstract:Abstract This experimental study investigates the combined effect of the three primary Additive Manufacturing (AM) build orientations (0°, 45°, and 90°) and an extensive array of heat treatment plans on the plastic anisotropy of maraging steel 300 (MS1) fabricated on the EOSINT M280 Direct Metal Laser Sintering (DMLS) System. The alloy's microstructure, hardness, tensile properties and plastic strain behaviour have been examined for various strengthening heat-treatment plans to assess the influence of the time and temperature combinations on plastic anisotropy and mechanical properties (e.g. strength, ductility). A comprehensive visual representation of the material's overall mechanical properties, for all three AM build orientations, against the various heat treatment plans is offered through time – temperature contour maps. Considerable plastic anisotropy has been confirmed in the as-built condition, which can be reduced by aging heat-treatment, as verified in this study. However, it has identified that a degree of transverse strain anisotropy is likely to remain due to the AM alloy's fabrication history, a finding that has not been previously reported in the literature. Moreover, the heat treatment plan (6h at 490 °C) recommended by the DMLS System Manufacturer has been found not to be the optimal in terms of achieving high strength, hardness, ductility and low anisotropy for the MS1 material. With the use of the comprehensive experimental data collected and analysed in this study, and presented in the constructed contour maps, the alloy's heat treatment parameters (time, temperature) can be tailored to meet the desired strength/ductility/anisotropy design requirements, either for research or part production purposes.
Daniela Chrenko - One of the best experts on this subject based on the ideXlab platform.
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Energetic Macroscopic Representation Modeling and Control of a Low Temperature Fuel Cell System Fed by Hydrocarbons
2008Co-Authors: Daniela ChrenkoAbstract:Fuel cell Systems (FCS) are considered to be upcoming technology for electrical power generation. They can be used for portable, stationary and transportation applications. Fuel cells are run on hydrogen. Hydrogen can be produced either by electrolysis using electricity from renewable energy or by converting conventional hydrocarbons into a hydrogen rich gas. Among others, a FCS incorporates two main components, the fuel processing unit and the fuel cell stack. The use of hydrocarbon fueled FCS as auxiliary power units (APU) in transportation applications is a possible entry market for this technology that utilizes the existing infrastructure of fuel supply. Hydrocarbon fueled FCSs are complex multi-domain Systems combining aspects from various energetic regimes, like electro-chemical, electrical, pneumatical and thermal. These Systems work only in a narrow and well defined range of operation. Therefore, this application requires a well adapted System control to respect these constraints. Classical control structure development often requires the transfer function of the System. This can be difficult or even impossible to derive for complex Systems. Therefore, control structure development for complex multi-domain Systems is often based on empirical observation and experience. It is desireable to find an approach that allows the development of a control structure based on System description. Such an approach will simplify control structure development and ensure that the control structure is adapted to the System needs. Model based control structure design is an approach that can meet these demands. This thesis presents a complete model of a low temperature FCS fueled by commercial diesel, and is well adapted for model based control development. The studied FCS provides 25kW electric power, and at the same time the System waste heat is used for climatization. In chapter 2 several modeling methodologies are introduced. Each is evaluated to see if it can be used to model a complex multi-domain System and if it can be used for model based control structure development. Energetic Macroscopic Representation (EMR) is identified as the best adapted methodology and is applied to chemical reactions and mass transfer. In chapter 3 a model of the fuel processor is presented and implemented in Matlab/Simulink\texttrademark. To obtain a hydrogen rich gas, the supplied hydrocarbon has to be broken up. Subsequently, the gas has to be purified in order to avoid contamination of the fuel cell with sulfur and carbon monoxide. In chapter 4 a model of the fuel cell stack is presented. It takes into account the gas flows in the different layers, describing membrane humidification as well as the voltage supplied by the fuel cell. The model also takes into account the influence of the membrane humidity on the stack voltage. Among low temperature fuel cells, two technologies are available. The model is developed for the more common (Polymer Electrolyte Fuel Cell - PEFC), but the emerging technology (High Temperature Proton Exchange Membrane Fuel Cell - HTPEMFC) shows advantages with regard to System volume and heat use. Therefore, the models of the fuel processor and the fuel cell stack have been adapted to this emerging technology. The demonstrated adaptability underlines the advantage of using a modular modeling approach. The models are validated successfully against measurements, literature values and values supplied by System Manufacturer. To confirm that the model can be used for model based control development, the control structure with regard to the temperature and the mass flow control for the FCS is developed in chapter 5. It is shown that the control structure of the System can be obtained by block wise inversion of the model. This approach gives the control structure; the choice of the controllers and their parameterization is up to the developer. The application of control proves that, using EMR, it is possible to derive a control structure from the model of a complex multi domain System without the need to derive its transfer function. The presented work is accomplished in cooperation with the French national project GAPPAC from the PAN-H program of the French National Agency for Research (ANR). It gathers N-GHY, Airbus and Nexter as industrial partners and LMFA, Armines, IFFI, INRETS LTN and FCLAB Institute as research institutes.
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Energetic Macroscopic Representation Modeling and Control of a Low Temperature Fuel Cell System Fed by Hydrocarbons
2008Co-Authors: Daniela ChrenkoAbstract:Fuel cell Systems (FCS) are considered to be upcoming technology for electrical power generation. They can be used for portable, stationary and transportation applications. Fuel cells are run on hydrogen. Hydrogen can be produced either by electrolysis using electricity from renewable energy or by converting conventional hydrocarbons into a hydrogen rich gas. Among others, a FCS incorporates two main components, the fuel processing unit and the fuel cell stack. The use of hydrocarbon fueled FCS as auxiliary power units (APU) in transportation applications is a possible entry market for this technology that utilizes the existing infrastructure of fuel supply. Hydrocarbon fueled FCSs are complex multi-domain Systems combining aspects from various energetic regimes, like electro-chemical, electrical, pneumatical and thermal. These Systems work only in a narrow and well defined range of operation. Therefore, this application requires a well adapted System control to respect these constraints. Classical control structure development often requires the transfer function of the System. This can be difficult or even impossible to derive for complex Systems. Therefore, control structure development for complex multi-domain Systems is often based on empirical observation and experience. It is desireable to find an approach that allows the development of a control structure based on System description. Such an approach will simplify control structure development and ensure that the control structure is adapted to the System needs. Model based control structure design is an approach that can meet these demands. This thesis presents a complete model of a low temperature FCS fueled by commercial diesel, and is well adapted for model based control development. The studied FCS provides 25kW electric power, and at the same time the System waste heat is used for climatization. In chapter 2 several modeling methodologies are introduced. Each is evaluated to see if it can be used to model a complex multi-domain System and if it can be used for model based control structure development. Energetic Macroscopic Representation (EMR) is identified as the best adapted methodology and is applied to chemical reactions and mass transfer. In chapter 3 a model of the fuel processor is presented and implemented in Matlab/Simulink\texttrademark. To obtain a hydrogen rich gas, the supplied hydrocarbon has to be broken up. Subsequently, the gas has to be purified in order to avoid contamination of the fuel cell with sulfur and carbon monoxide. In chapter 4 a model of the fuel cell stack is presented. It takes into account the gas flows in the different layers, describing membrane humidification as well as the voltage supplied by the fuel cell. The model also takes into account the influence of the membrane humidity on the stack voltage. Among low temperature fuel cells, two technologies are available. The model is developed for the more common (Polymer Electrolyte Fuel Cell - PEFC), but the emerging technology (High Temperature Proton Exchange Membrane Fuel Cell - HTPEMFC) shows advantages with regard to System volume and heat use. Therefore, the models of the fuel processor and the fuel cell stack have been adapted to this emerging technology. The demonstrated adaptability underlines the advantage of using a modular modeling approach. The models are validated successfully against measurements, literature values and values supplied by System Manufacturer. To confirm that the model can be used for model based control development, the control structure with regard to the temperature and the mass flow control for the FCS is developed in chapter 5. It is shown that the control structure of the System can be obtained by block wise inversion of the model. This approach gives the control structure; the choice of the controllers and their parameterization is up to the developer. The application of control proves that, using EMR, it is possible to derive a control structure from the model of a complex multi domain System without the need to derive its transfer function. The presented work is accomplished in cooperation with the French national project GAPPAC from the PAN-H program of the French National Agency for Research (ANR). It gathers N-GHY, Airbus and Nexter as industrial partners and LMFA, Armines, IFFI, INRETS LTN and FCLAB Institute as research institutes.
Barry Mooney - One of the best experts on this subject based on the ideXlab platform.
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plastic anisotropy of additively manufactured maraging steel influence of the build orientation and heat treatments
Additive manufacturing, 2019Co-Authors: Barry Mooney, Kyriakos I Kourousis, Ramesh RaghavendraAbstract:Abstract This experimental study investigates the combined effect of the three primary Additive Manufacturing (AM) build orientations (0°, 45°, and 90°) and an extensive array of heat treatment plans on the plastic anisotropy of maraging steel 300 (MS1) fabricated on the EOSINT M280 Direct Metal Laser Sintering (DMLS) System. The alloy's microstructure, hardness, tensile properties and plastic strain behaviour have been examined for various strengthening heat-treatment plans to assess the influence of the time and temperature combinations on plastic anisotropy and mechanical properties (e.g. strength, ductility). A comprehensive visual representation of the material's overall mechanical properties, for all three AM build orientations, against the various heat treatment plans is offered through time – temperature contour maps. Considerable plastic anisotropy has been confirmed in the as-built condition, which can be reduced by aging heat-treatment, as verified in this study. However, it has identified that a degree of transverse strain anisotropy is likely to remain due to the AM alloy's fabrication history, a finding that has not been previously reported in the literature. Moreover, the heat treatment plan (6h at 490 °C) recommended by the DMLS System Manufacturer has been found not to be the optimal in terms of achieving high strength, hardness, ductility and low anisotropy for the MS1 material. With the use of the comprehensive experimental data collected and analysed in this study, and presented in the constructed contour maps, the alloy's heat treatment parameters (time, temperature) can be tailored to meet the desired strength/ductility/anisotropy design requirements, either for research or part production purposes.
Raghavendra Ramesh - One of the best experts on this subject based on the ideXlab platform.
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Plastic anisotropy of additively manufactured maraging steel: influence of the build orientation and heat treatments
'Elsevier BV', 2019Co-Authors: Mooney Barry, Kourousis Kyriakos, Raghavendra RameshAbstract:peer-reviewedThis experimental study investigates the combined effect of the three primary Additive Manufacturing (AM) build orientations (0°, 45°, and 90°) and an extensive array of heat treatment plans on the plastic anisotropy of maraging steel 300 (MS1) fabricated on the EOSINT M280 Direct Metal Laser Sintering (DMLS) System. The alloy's microstructure, hardness, tensile properties and plastic strain behaviour have been examined for various strengthening heat-treatment plans to assess the influence of the time and temperature combinations on plastic anisotropy and mechanical properties (e.g. strength, ductility). A comprehensive visual representation of the material's overall mechanical properties, for all three AM build orientations, against the various heat treatment plans is offered through time – temperature contour maps. Considerable plastic anisotropy has been confirmed in the as-built condition, which can be reduced by aging heat-treatment, as verified in this study. However, it has identified that a degree of transverse strain anisotropy is likely to remain due to the AM alloy's fabrication history, a finding that has not been previously reported in the literature. Moreover, the heat treatment plan (6h at 490 °C) recommended by the DMLS System Manufacturer has been found not to be the optimal in terms of achieving high strength, hardness, ductility and low anisotropy for the MS1 material. With the use of the comprehensive experimental data collected and analysed in this study, and presented in the constructed contour maps, the alloy's heat treatment parameters (time, temperature) can be tailored to meet the desired strength/ductility/anisotropy design requirements, either for research or part production purposes
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Plastic anisotropy of additively manufactured maraging steel: influence of the build orientation and heat treatments
Elsevier, 2019Co-Authors: Mooney Barry, Kourousis Kyriakos, Raghavendra RameshAbstract:peer-reviewedThe full text of this article will not be available in ULIR until the embargo expires on the 31/10/2020This experimental study investigates the combined effect of the three primary Additive Manufacturing (AM) build orientations (0°, 45°, and 90°) and an extensive array of heat treatment plans on the plastic anisotropy of maraging steel 300 (MS1) fabricated on the EOSINT M280 Direct Metal Laser Sintering (DMLS) System. The alloy's microstructure, hardness, tensile properties and plastic strain behaviour have been examined for various strengthening heat-treatment plans to assess the influence of the time and temperature combinations on plastic anisotropy and mechanical properties (e.g. strength, ductility). A comprehensive visual representation of the material's overall mechanical properties, for all three AM build orientations, against the various heat treatment plans is offered through time – temperature contour maps. Considerable plastic anisotropy has been confirmed in the as-built condition, which can be reduced by aging heat-treatment, as verified in this study. However, it has identified that a degree of transverse strain anisotropy is likely to remain due to the AM alloy's fabrication history, a finding that has not been previously reported in the literature. Moreover, the heat treatment plan (6h at 490 °C) recommended by the DMLS System Manufacturer has been found not to be the optimal in terms of achieving high strength, hardness, ductility and low anisotropy for the MS1 material. With the use of the comprehensive experimental data collected and analysed in this study, and presented in the constructed contour maps, the alloy's heat treatment parameters (time, temperature) can be tailored to meet the desired strength/ductility/anisotropy design requirements, either for research or part production purposes
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Plastic anisotropy of additively manufactured maraging steel: influence of the build orientation and heat treatments
Elsevier, 2019Co-Authors: Mooney Barry, Kourousis Kyriakos, Raghavendra RameshAbstract:The full text of this article will not be available in ULIR until the embargo expires on the 31/10/2020This experimental study investigates the combined effect of the three primary Additive Manufacturing (AM) build orientations (0°, 45°, and 90°) and an extensive array of heat treatment plans on the plastic anisotropy of maraging steel 300 (MS1) fabricated on the EOSINT M280 Direct Metal Laser Sintering (DMLS) System. The alloy\u27s microstructure, hardness, tensile properties and plastic strain behaviour have been examined for various strengthening heat-treatment plans to assess the influence of the time and temperature combinations on plastic anisotropy and mechanical properties (e.g. strength, ductility). A comprehensive visual representation of the material\u27s overall mechanical properties, for all three AM build orientations, against the various heat treatment plans is offered through time – temperature contour maps. Considerable plastic anisotropy has been confirmed in the as-built condition, which can be reduced by aging heat-treatment, as verified in this study. However, it has identified that a degree of transverse strain anisotropy is likely to remain due to the AM alloy\u27s fabrication history, a finding that has not been previously reported in the literature. Moreover, the heat treatment plan (6h at 490 °C) recommended by the DMLS System Manufacturer has been found not to be the optimal in terms of achieving high strength, hardness, ductility and low anisotropy for the MS1 material. With the use of the comprehensive experimental data collected and analysed in this study, and presented in the constructed contour maps, the alloy\u27s heat treatment parameters (time, temperature) can be tailored to meet the desired strength/ductility/anisotropy design requirements, either for research or part production purposes
Kyriakos I Kourousis - One of the best experts on this subject based on the ideXlab platform.
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plastic anisotropy of additively manufactured maraging steel influence of the build orientation and heat treatments
Additive manufacturing, 2019Co-Authors: Barry Mooney, Kyriakos I Kourousis, Ramesh RaghavendraAbstract:Abstract This experimental study investigates the combined effect of the three primary Additive Manufacturing (AM) build orientations (0°, 45°, and 90°) and an extensive array of heat treatment plans on the plastic anisotropy of maraging steel 300 (MS1) fabricated on the EOSINT M280 Direct Metal Laser Sintering (DMLS) System. The alloy's microstructure, hardness, tensile properties and plastic strain behaviour have been examined for various strengthening heat-treatment plans to assess the influence of the time and temperature combinations on plastic anisotropy and mechanical properties (e.g. strength, ductility). A comprehensive visual representation of the material's overall mechanical properties, for all three AM build orientations, against the various heat treatment plans is offered through time – temperature contour maps. Considerable plastic anisotropy has been confirmed in the as-built condition, which can be reduced by aging heat-treatment, as verified in this study. However, it has identified that a degree of transverse strain anisotropy is likely to remain due to the AM alloy's fabrication history, a finding that has not been previously reported in the literature. Moreover, the heat treatment plan (6h at 490 °C) recommended by the DMLS System Manufacturer has been found not to be the optimal in terms of achieving high strength, hardness, ductility and low anisotropy for the MS1 material. With the use of the comprehensive experimental data collected and analysed in this study, and presented in the constructed contour maps, the alloy's heat treatment parameters (time, temperature) can be tailored to meet the desired strength/ductility/anisotropy design requirements, either for research or part production purposes.
