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Gérard Degallaix - One of the best experts on this subject based on the ideXlab platform.
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coupling between friction physical mechanisms and transient Thermal Phenomena involved in pad disc contact during railway braking
Wear, 2007Co-Authors: Annelise Cristolbulthe, Yannick Desplanques, Gérard DegallaixAbstract:During railway braking, friction dissipates high energy, leading to transient and localized Thermal Phenomena such as hot bands and hot spots. These Thermal Phenomena interact with third-body flows and friction mechanisms activated in the contact. To provide information on the transient character of these physical mechanisms, severe stop-braking conditions are reproduced on a specially designed braking tribometer. Thermal Phenomena observed by infrared thermography on the disc-track are characterised and correlated to the evolution of the friction coefficient. In view to studying the coupling between Thermal Phenomena and friction mechanisms, rubbing surfaces are observed and analysed at typical stages of braking in correlation with the corresponding disc-track thermograms. The results show how third-body flows, resulting from the waviness distortion of the disc, feed the contact and lead to the formation of the third-body in the form of flat plates that stabilize the friction coefficient.
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Coupling between friction physical mechanisms and transient Thermal Phenomena involved in pad–disc contact during railway braking
Wear, 2007Co-Authors: Anne-lise Cristol-bulthé, Yannick Desplanques, Gérard DegallaixAbstract:During railway braking, friction dissipates high energy, leading to transient and localized Thermal Phenomena such as hot bands and hot spots. These Thermal Phenomena interact with third-body flows and friction mechanisms activated in the contact. To provide information on the transient character of these physical mechanisms, severe stop-braking conditions are reproduced on a specially designed braking tribometer. Thermal Phenomena observed by infrared thermography on the disc-track are characterised and correlated to the evolution of the friction coefficient. In view to studying the coupling between Thermal Phenomena and friction mechanisms, rubbing surfaces are observed and analysed at typical stages of braking in correlation with the corresponding disc-track thermograms. The results show how third-body flows, resulting from the waviness distortion of the disc, feed the contact and lead to the formation of the third-body in the form of flat plates that stabilize the friction coefficient.
Marcin Kubiak - One of the best experts on this subject based on the ideXlab platform.
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Comprehensive model of Thermal Phenomena and phase transformations in laser welding process
Computers & Structures, 2016Co-Authors: Marcin Kubiak, Wiesława PiekarskaAbstract:Prediction of fusion zone and heat affected zone geometry in laser welding process.Estimation of structural composition of the laser welded joint.Considering austenitization temperatures changing with heating rates.Determining the impact of latent heats on the temperature field.Comparison of predicted characteristic zones of joints with experimental results. This paper concerns computational modelling of Thermal Phenomena and phase transformations in solid state in laser welding process. The analysis is performed on the basis of numerical solution into continuum mechanics governing equations as well as classic Johnson-Mehl-Avrami (JMA) and Koistinen-Marburger (KM) kinetics models with continuous heating transformation (CHT) and continuous cooling transformation (CCT) diagrams of S460 steel. The influence of latent heats on temperature distributions is analysed. Obtained results include temperature field, melted material velocity field in the fusion zone and structure composition of welded joint. Calculations are partially verified by experimental data.
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NUMERICAL MODELLING OF Thermal Phenomena IN Yb:YAG LASER WELDING PROCESS
Journal of Applied Mathematics and Computational Mechanics, 2014Co-Authors: Wiesława Piekarska, T. Domański, Marcin Kubiak, Zbigniew Saternus, Sebastian Stano, Michail V. Radcenko, Sergiej G. IvanovAbstract:This paper concerns numerical modelling of the Yb:YAG laser beam welding process. Numerical algorithms are developed for the analysis of Thermal Phenomena in a laser welded joint taking into account the motion of the liquid material in the welding pool. The model describing the laser beam heat source power distribution is developed on the basis of the kriging method. The heat source model uses the real laser beam profile obtained from experimental measurements of the beam emitted from a Trumpf D70 laser head performed on UFF100 analyzer. On the basis of developed numerical algorithms computer simulations of a Yb:YAG laser beam welding are carried out used to analyze the influence of the Thermal load model on the shape and size of the weld.
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three dimensional model for numerical analysis of Thermal Phenomena in laser arc hybrid welding process
International Journal of Heat and Mass Transfer, 2011Co-Authors: Wiesława Piekarska, Marcin KubiakAbstract:Abstract This paper describes mathematical and numerical models of Thermal Phenomena developed for computational analysis of the laser–arc hybrid welding process. The mathematical and numerical models were established to estimate temperature field and velocity field of melted material in the welding pool. Different heat source power distribution models for electric arc and laser beam, latent heat of fusion and latent heat of evaporation as well as buoyancy and liquid material flow through a porous medium were taken into consideration in the computational model. The results of computer simulation of laser–arc hybrid welding process, including temperature field and melted material velocity field, are presented in this study. The correctness of elaborated models is verified by experimental results.
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Three-dimensional model for numerical analysis of Thermal Phenomena in laser–arc hybrid welding process
International Journal of Heat and Mass Transfer, 2011Co-Authors: Wiesława Piekarska, Marcin KubiakAbstract:Abstract This paper describes mathematical and numerical models of Thermal Phenomena developed for computational analysis of the laser–arc hybrid welding process. The mathematical and numerical models were established to estimate temperature field and velocity field of melted material in the welding pool. Different heat source power distribution models for electric arc and laser beam, latent heat of fusion and latent heat of evaporation as well as buoyancy and liquid material flow through a porous medium were taken into consideration in the computational model. The results of computer simulation of laser–arc hybrid welding process, including temperature field and melted material velocity field, are presented in this study. The correctness of elaborated models is verified by experimental results.
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Numerical modelling of Thermal Phenomena in laser beam and hybrid welding processes using Abaqus FEA
Archives of Foundry Engineering, 2011Co-Authors: Wiesława Piekarska, Marcin Kubiak, Zbigniew SaternusAbstract:This paper concerns numerical analysis of Thermal Phenomena accompanying laser beam and laser-arc hybrid welding processes. Temperature field was obtained on the basis of the solution into energy conservation equation with Fourier law using finite element method. ABAQUS/Standard solver was used for calculations. Electric arc and laser beam heat sources were described respectively by “double ellipsoidal” heat source and Gaussian distribution with assumption of linear decrease of heat source power intensity with material penetration deep. Heat source movement along welded plate was obtained using DFLUX subroutine. Thermo-physical parameters dependant on temperature as well as latent heat of fusion were taken into account in FE analysis. The results of calculations include temperature field in rectangular elements butt welded by a single laser beam and hybrid laser-arc technique.
Wiesława Piekarska - One of the best experts on this subject based on the ideXlab platform.
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Comprehensive model of Thermal Phenomena and phase transformations in laser welding process
Computers & Structures, 2016Co-Authors: Marcin Kubiak, Wiesława PiekarskaAbstract:Prediction of fusion zone and heat affected zone geometry in laser welding process.Estimation of structural composition of the laser welded joint.Considering austenitization temperatures changing with heating rates.Determining the impact of latent heats on the temperature field.Comparison of predicted characteristic zones of joints with experimental results. This paper concerns computational modelling of Thermal Phenomena and phase transformations in solid state in laser welding process. The analysis is performed on the basis of numerical solution into continuum mechanics governing equations as well as classic Johnson-Mehl-Avrami (JMA) and Koistinen-Marburger (KM) kinetics models with continuous heating transformation (CHT) and continuous cooling transformation (CCT) diagrams of S460 steel. The influence of latent heats on temperature distributions is analysed. Obtained results include temperature field, melted material velocity field in the fusion zone and structure composition of welded joint. Calculations are partially verified by experimental data.
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NUMERICAL MODELLING OF Thermal Phenomena IN Yb:YAG LASER WELDING PROCESS
Journal of Applied Mathematics and Computational Mechanics, 2014Co-Authors: Wiesława Piekarska, T. Domański, Marcin Kubiak, Zbigniew Saternus, Sebastian Stano, Michail V. Radcenko, Sergiej G. IvanovAbstract:This paper concerns numerical modelling of the Yb:YAG laser beam welding process. Numerical algorithms are developed for the analysis of Thermal Phenomena in a laser welded joint taking into account the motion of the liquid material in the welding pool. The model describing the laser beam heat source power distribution is developed on the basis of the kriging method. The heat source model uses the real laser beam profile obtained from experimental measurements of the beam emitted from a Trumpf D70 laser head performed on UFF100 analyzer. On the basis of developed numerical algorithms computer simulations of a Yb:YAG laser beam welding are carried out used to analyze the influence of the Thermal load model on the shape and size of the weld.
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three dimensional model for numerical analysis of Thermal Phenomena in laser arc hybrid welding process
International Journal of Heat and Mass Transfer, 2011Co-Authors: Wiesława Piekarska, Marcin KubiakAbstract:Abstract This paper describes mathematical and numerical models of Thermal Phenomena developed for computational analysis of the laser–arc hybrid welding process. The mathematical and numerical models were established to estimate temperature field and velocity field of melted material in the welding pool. Different heat source power distribution models for electric arc and laser beam, latent heat of fusion and latent heat of evaporation as well as buoyancy and liquid material flow through a porous medium were taken into consideration in the computational model. The results of computer simulation of laser–arc hybrid welding process, including temperature field and melted material velocity field, are presented in this study. The correctness of elaborated models is verified by experimental results.
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Three-dimensional model for numerical analysis of Thermal Phenomena in laser–arc hybrid welding process
International Journal of Heat and Mass Transfer, 2011Co-Authors: Wiesława Piekarska, Marcin KubiakAbstract:Abstract This paper describes mathematical and numerical models of Thermal Phenomena developed for computational analysis of the laser–arc hybrid welding process. The mathematical and numerical models were established to estimate temperature field and velocity field of melted material in the welding pool. Different heat source power distribution models for electric arc and laser beam, latent heat of fusion and latent heat of evaporation as well as buoyancy and liquid material flow through a porous medium were taken into consideration in the computational model. The results of computer simulation of laser–arc hybrid welding process, including temperature field and melted material velocity field, are presented in this study. The correctness of elaborated models is verified by experimental results.
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Numerical modelling of Thermal Phenomena in laser beam and hybrid welding processes using Abaqus FEA
Archives of Foundry Engineering, 2011Co-Authors: Wiesława Piekarska, Marcin Kubiak, Zbigniew SaternusAbstract:This paper concerns numerical analysis of Thermal Phenomena accompanying laser beam and laser-arc hybrid welding processes. Temperature field was obtained on the basis of the solution into energy conservation equation with Fourier law using finite element method. ABAQUS/Standard solver was used for calculations. Electric arc and laser beam heat sources were described respectively by “double ellipsoidal” heat source and Gaussian distribution with assumption of linear decrease of heat source power intensity with material penetration deep. Heat source movement along welded plate was obtained using DFLUX subroutine. Thermo-physical parameters dependant on temperature as well as latent heat of fusion were taken into account in FE analysis. The results of calculations include temperature field in rectangular elements butt welded by a single laser beam and hybrid laser-arc technique.
G Brunetti - One of the best experts on this subject based on the ideXlab platform.
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cluster mergers and non Thermal Phenomena a statistical magneto turbulent model
Monthly Notices of the Royal Astronomical Society, 2005Co-Authors: Rossella Cassano, G BrunettiAbstract:There is now firm evidence that the intracluster medium (ICM) consists of a mixture of hot plasma, magnetic fields and relativistic particles. The most important evidence for non-Thermal Phenomena in galaxy clusters comes from the spectacular synchrotron radio emission diffused over Mpc scales observed in a growing number of massive clusters and, more recently, in the hard X-ray tails detected in a few cases in excess of the Thermal bremsstrahlung spectrum. A promising possibility to explain giant radio haloes is given by the presence of relativistic electrons reaccelerated by some kind of turbulence generated in the cluster volume during merger events. With the aim of investigating the connection between Thermal and non-Thermal properties of the ICM, in this paper we develop a statistical magneto-turbulent model which describes in a self-consistent way the evolution of the Thermal ICM and that of the non-Thermal emission from clusters. Making use of the extended Press-Schechter formalism, we follow cluster mergers and estimate the injection rate of the fluid turbulence generated during these energetic events. We then calculate the evolution of the spectrum of the relativistic electrons in the ICM during the cluster life by taking into account both the electron acceleration due to the merger-driven turbulence and the relevant energy losses of the electrons. We end up with a synthetic population of galaxy clusters for which the evolution of the ICM and of the non-Thermal spectrum emitted by the accelerated electrons is calculated. The generation of detectable non-Thermal radio and hard X-ray emission in the simulated clusters is found to be possible during major merger events for reliable values of the model parameters. In addition the occurrence of radio haloes as a function of the mass of the parent clusters is calculated and compared with observations. In this case it is found that the model expectations are in good agreement with observations: radio haloes are found in about 30 per cent of the more massive clusters in our synthetic population (M ≥ 1.8 x 10 15 M ○. ) and in about 4 per cent of the intermediate massive clusters (9 x 10 14 < M < 1.8 × 10 15 M ○. ), while the radio halo phenomenon is found to be extremely rare in the case of the smaller clusters.
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cluster mergers and non Thermal Phenomena a statistical magneto turbulent model
Journal of the Korean Astronomical Society, 2004Co-Authors: R Cassano, G BrunettiAbstract:With the aim to investigate the statistical properties and the connection between Thermal and non-Thermal properties of the ICM in galaxy clusters, we have developed a statistical magneto-turbulent model which describes, at the same time, the evolution of the Thermal and non-Thermal emission from galaxy clusters. In particular, starting from the cosmological evolution of clusters, we follow cluster. mergers, calculate the spectrum of the magnetosonic waves generated in the ICM during these mergers, the evolution of relativistic electrons and the resulting synchrotron and Inverse Compton spectra. We show that the broad band (radio and hard x-ray) non-Thermal spectral properties of galaxy clusters can be well accounted for by our model for viable values of the parameters (here we adopt a EdS cosmology).
Yannick Desplanques - One of the best experts on this subject based on the ideXlab platform.
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coupling between friction physical mechanisms and transient Thermal Phenomena involved in pad disc contact during railway braking
Wear, 2007Co-Authors: Annelise Cristolbulthe, Yannick Desplanques, Gérard DegallaixAbstract:During railway braking, friction dissipates high energy, leading to transient and localized Thermal Phenomena such as hot bands and hot spots. These Thermal Phenomena interact with third-body flows and friction mechanisms activated in the contact. To provide information on the transient character of these physical mechanisms, severe stop-braking conditions are reproduced on a specially designed braking tribometer. Thermal Phenomena observed by infrared thermography on the disc-track are characterised and correlated to the evolution of the friction coefficient. In view to studying the coupling between Thermal Phenomena and friction mechanisms, rubbing surfaces are observed and analysed at typical stages of braking in correlation with the corresponding disc-track thermograms. The results show how third-body flows, resulting from the waviness distortion of the disc, feed the contact and lead to the formation of the third-body in the form of flat plates that stabilize the friction coefficient.
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Coupling between friction physical mechanisms and transient Thermal Phenomena involved in pad–disc contact during railway braking
Wear, 2007Co-Authors: Anne-lise Cristol-bulthé, Yannick Desplanques, Gérard DegallaixAbstract:During railway braking, friction dissipates high energy, leading to transient and localized Thermal Phenomena such as hot bands and hot spots. These Thermal Phenomena interact with third-body flows and friction mechanisms activated in the contact. To provide information on the transient character of these physical mechanisms, severe stop-braking conditions are reproduced on a specially designed braking tribometer. Thermal Phenomena observed by infrared thermography on the disc-track are characterised and correlated to the evolution of the friction coefficient. In view to studying the coupling between Thermal Phenomena and friction mechanisms, rubbing surfaces are observed and analysed at typical stages of braking in correlation with the corresponding disc-track thermograms. The results show how third-body flows, resulting from the waviness distortion of the disc, feed the contact and lead to the formation of the third-body in the form of flat plates that stabilize the friction coefficient.
