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http://hdl.handle.net/10985/9903
Modelling surface tension with smoothed particle hydrodynamics in reactive rotational moulding
HAMIDI, A; KHELLADI, Sofiane; ILLOUL, Lounès; SHIRINBAYAN, Mohammadali; BAKIR, Farid; TCHARKHTCHI, Abbas
Reactive Rotational Moulding (RRM) is the best process for producing large hollow plastic parts without weld lines. Constant quality in technical parts requires the process to be mastered by controlling on-line the main physical phenomena. However, the main drawback of RRM is poor control of the process due to the high number of influent parameters. In these conditions, the optimization of the process is quite complex. The aim of this work is to simulate the reactive fluid flow during RRM with Smoothed Particle Hydrodynamics (SPH) solver in two dimensions (2D) and three dimensions (3D) taking into account surface tension force. To implement this force, the interface is tracked explicitly using algorithm developed by Barecasco et al. (2013) and Terissa et al. (2013) and the reconstruction of curve or surface boundary by different interpolation or surface construction technique with Lagrangian interpolation and fitting circle methods in 2D and spherical regression in 3D, respectively.
Thu, 01 Jan 2015 00:00:00 GMThttp://hdl.handle.net/10985/99032015-01-01T00:00:00ZHAMIDI, AKHELLADI, SofianeILLOUL, LounèsSHIRINBAYAN, MohammadaliBAKIR, FaridTCHARKHTCHI, AbbasReactive Rotational Moulding (RRM) is the best process for producing large hollow plastic parts without weld lines. Constant quality in technical parts requires the process to be mastered by controlling on-line the main physical phenomena. However, the main drawback of RRM is poor control of the process due to the high number of influent parameters. In these conditions, the optimization of the process is quite complex. The aim of this work is to simulate the reactive fluid flow during RRM with Smoothed Particle Hydrodynamics (SPH) solver in two dimensions (2D) and three dimensions (3D) taking into account surface tension force. To implement this force, the interface is tracked explicitly using algorithm developed by Barecasco et al. (2013) and Terissa et al. (2013) and the reconstruction of curve or surface boundary by different interpolation or surface construction technique with Lagrangian interpolation and fitting circle methods in 2D and spherical regression in 3D, respectively.Shear-strain step response in linear regime of dilute suspensions of naturally bent carbon nanotubes
http://hdl.handle.net/10985/6800
Shear-strain step response in linear regime of dilute suspensions of naturally bent carbon nanotubes
CRUZ, Camilo; ILLOUL, Lounès; CHINESTA, Francisco; REGNIER, Gilles
Impressive enhancements of the storage modulus have been documented when low volume fractions of single wall carbon nanotubes (SWNTs) are added to a Newtonian solvent for obtaining dilute suspensions. The intrinsic bending dynamics of carbon nanotubes (CNTs) has been proposed to explain such elasticity. CNTs contain topological defects inducing naturally bent structures in absence of external forces and, hence, a semiflexible filament with a bent configuration at minimal internal-bending-energy is used for mimicking the structure of SWNTs in suspension. Previous continuous model is discretized as a non-freely jointed bead-rod chain with a naturally bent configuration for simulating the rheological behaviour after a shear-strain step in linear regime of SWNT dilute suspension by using a Brownian dynamics (BD) approach. In general, bead-rod chains exhibit an instantaneous relaxation after a high shear-strain step. Bending rigidity and number of constitutive rods are found to be determinant parameters in the internal-energy relaxation behaviour of non-freely jointed bead-rod chains in dilute solution. Proper comparisons between the BD simulation results and the experimental data for treated SWNT dilute suspensions confirm the consistency of the physical model mimicking the structure of a SWNT.
Sun, 01 Jan 2012 00:00:00 GMThttp://hdl.handle.net/10985/68002012-01-01T00:00:00ZCRUZ, CamiloILLOUL, LounèsCHINESTA, FranciscoREGNIER, GillesImpressive enhancements of the storage modulus have been documented when low volume fractions of single wall carbon nanotubes (SWNTs) are added to a Newtonian solvent for obtaining dilute suspensions. The intrinsic bending dynamics of carbon nanotubes (CNTs) has been proposed to explain such elasticity. CNTs contain topological defects inducing naturally bent structures in absence of external forces and, hence, a semiflexible filament with a bent configuration at minimal internal-bending-energy is used for mimicking the structure of SWNTs in suspension. Previous continuous model is discretized as a non-freely jointed bead-rod chain with a naturally bent configuration for simulating the rheological behaviour after a shear-strain step in linear regime of SWNT dilute suspension by using a Brownian dynamics (BD) approach. In general, bead-rod chains exhibit an instantaneous relaxation after a high shear-strain step. Bending rigidity and number of constitutive rods are found to be determinant parameters in the internal-energy relaxation behaviour of non-freely jointed bead-rod chains in dilute solution. Proper comparisons between the BD simulation results and the experimental data for treated SWNT dilute suspensions confirm the consistency of the physical model mimicking the structure of a SWNT.Effects of a bent structure on the linear viscoelastic response of diluted carbon nanotube suspensions
http://hdl.handle.net/10985/17960
Effects of a bent structure on the linear viscoelastic response of diluted carbon nanotube suspensions
CRUZ, Camilo; ILLOUL, Lounès; CHINESTA, Francisco; REGNIER, Gilles
Commonly isolated carbon nanotubes in suspension have been modelled as a perfectly straight structure. Nevertheless, single-wall carbon nanotubes (SWNTs) contain naturally side-wall defects and, in consequence, natural bent configurations. Hence, a semi-flexile filament model with a natural bent configuration was proposed to represent physically the SWNT structure. This continuous model was discretized as a non-freely jointed multi-bead-rod system with a natural bent configuration. Using a Brownian dynamics algorithm the dynamical mechanical contribution to the linear viscoelastic response of naturally bent SWNTs in dilute suspension was simulated. The dynamics of such system shows the apparition of new relaxation processes at intermediate frequencies characterized mainly by the activation of a mild elasticity. Storage modulus evolution at those intermediate frequencies strongly depends on the flexibility of the system, given by the rigidity constant of the bending potential and the number of constitutive rods.
Fri, 01 Jan 2010 00:00:00 GMThttp://hdl.handle.net/10985/179602010-01-01T00:00:00ZCRUZ, CamiloILLOUL, LounèsCHINESTA, FranciscoREGNIER, GillesCommonly isolated carbon nanotubes in suspension have been modelled as a perfectly straight structure. Nevertheless, single-wall carbon nanotubes (SWNTs) contain naturally side-wall defects and, in consequence, natural bent configurations. Hence, a semi-flexile filament model with a natural bent configuration was proposed to represent physically the SWNT structure. This continuous model was discretized as a non-freely jointed multi-bead-rod system with a natural bent configuration. Using a Brownian dynamics algorithm the dynamical mechanical contribution to the linear viscoelastic response of naturally bent SWNTs in dilute suspension was simulated. The dynamics of such system shows the apparition of new relaxation processes at intermediate frequencies characterized mainly by the activation of a mild elasticity. Storage modulus evolution at those intermediate frequencies strongly depends on the flexibility of the system, given by the rigidity constant of the bending potential and the number of constitutive rods.Phénomènes dynamiques en usinage : Prédiction de l’état géométrique des surfaces usinées
http://hdl.handle.net/10985/9952
Phénomènes dynamiques en usinage : Prédiction de l’état géométrique des surfaces usinées
COFFIGNAL, Gérard; DUCHEMIN, Jérôme; ILLOUL, Lounès; GENGEMBRE, Christophe; GUSKOV, Mikhail; LORONG, Philippe
Présentation concernant la modélisation des phénomènes dynamiques en usinage. Cette modélisation a pour particularité de permettre la prédiction de la géométrie des surfaces usinées (défauts de forme, d'ondulation) que la pièce soit considérée comme rigide ou flexible.
Tue, 01 Jan 2013 00:00:00 GMThttp://hdl.handle.net/10985/99522013-01-01T00:00:00ZCOFFIGNAL, GérardDUCHEMIN, JérômeILLOUL, LounèsGENGEMBRE, ChristopheGUSKOV, MikhailLORONG, PhilippePrésentation concernant la modélisation des phénomènes dynamiques en usinage. Cette modélisation a pour particularité de permettre la prédiction de la géométrie des surfaces usinées (défauts de forme, d'ondulation) que la pièce soit considérée comme rigide ou flexible.On some aspects of the CNEM implementation in 3D in order to simulate high speed machining or shearing
http://hdl.handle.net/10985/9871
On some aspects of the CNEM implementation in 3D in order to simulate high speed machining or shearing
ILLOUL, Lounès; LORONG, Philippe
his paper deals with the implementation in 3D of the constrained natural element method (CNEM) in order to simulate material forming involving large strains. The CNEM is a member of the large family of mesh-free methods, but is at the same time very close to the finite element method. The CNEM’s shape function is built using the constrained Voronoï diagram (the dual of the constrained Delaunay tessella- tion) associated with a domain defined by a set of nodes and a description of its border. The use of the CNEM involves three main steps. First, the constrained Voronoï diagram is built. Thus, for each node, a Voronoï cell is geometrically defined, with respect of the boundary of the domain. Then, the Sibson-type CNEM shape functions are computed. Finally, the discretization of a generic variational for- mulation is defined by invoking an ‘‘stabilized conforming nodal integration’’. In this work, we focus especially on the two last points. In order to compute the Sibson shape function, five algorithms are pre- sented, analyzed and compared, two of them are developed. For the integration task, a discretization strategy is proposed to handle domains with strong non-convexities. These approaches are validated on some 3D benchmarks in elasticity under the hypothesis of small transformations. The obtained results are compared with analytical solutions and with finite elements results. Finally, the 3D CNEM is applied for addressing two forming processes: high speed shearing and machining.
Sat, 01 Jan 2011 00:00:00 GMThttp://hdl.handle.net/10985/98712011-01-01T00:00:00ZILLOUL, LounèsLORONG, Philippehis paper deals with the implementation in 3D of the constrained natural element method (CNEM) in order to simulate material forming involving large strains. The CNEM is a member of the large family of mesh-free methods, but is at the same time very close to the finite element method. The CNEM’s shape function is built using the constrained Voronoï diagram (the dual of the constrained Delaunay tessella- tion) associated with a domain defined by a set of nodes and a description of its border. The use of the CNEM involves three main steps. First, the constrained Voronoï diagram is built. Thus, for each node, a Voronoï cell is geometrically defined, with respect of the boundary of the domain. Then, the Sibson-type CNEM shape functions are computed. Finally, the discretization of a generic variational for- mulation is defined by invoking an ‘‘stabilized conforming nodal integration’’. In this work, we focus especially on the two last points. In order to compute the Sibson shape function, five algorithms are pre- sented, analyzed and compared, two of them are developed. For the integration task, a discretization strategy is proposed to handle domains with strong non-convexities. These approaches are validated on some 3D benchmarks in elasticity under the hypothesis of small transformations. The obtained results are compared with analytical solutions and with finite elements results. Finally, the 3D CNEM is applied for addressing two forming processes: high speed shearing and machining.Modeling laser drilling in percussion regime using constraint natural element method
http://hdl.handle.net/10985/11714
Modeling laser drilling in percussion regime using constraint natural element method
GIRARDOT, Jérémie; ILLOUL, Lounès; SCHNEIDER, Matthieu; FAVIER, VERONIQUE; LORONG, Philippe; RANC, Nicolas
The laser drilling process is the main process used in machining procedures on aeronautic engines, especially in the cooling parts. The industrial problematic is to reduce geometrical deviations of the holes and defects during manufacturing. The interaction between a laser beam and an absorbent metallic matter in the laser drilling regime involves thermal and hydrodynamical phenomenon. Their role on the drilling is not yet completely understood and a realistic simulation of the process could contribute to a better understanding of these phenomenon. The simulation of such process induces strong numerical difficulties. This work presents a physical model combined with the use of the original Constraint Natural Element Method to simulate the laser drilling. The physical model includes solid/liquid and liquid/vapor phase transformations, the liquid ejection and the convective and conductive thermal exchanges. It is the first time that all these phenomena are included in a modelling and numerically solved in a 2D axisymmmetric problem. Simulations results predict most of measurements (hole geometry, velocity of the liquid ejection and laser drilling velocity) without adjusting any parameters
Sun, 01 Jan 2017 00:00:00 GMThttp://hdl.handle.net/10985/117142017-01-01T00:00:00ZGIRARDOT, JérémieILLOUL, LounèsSCHNEIDER, MatthieuFAVIER, VERONIQUELORONG, PhilippeRANC, NicolasThe laser drilling process is the main process used in machining procedures on aeronautic engines, especially in the cooling parts. The industrial problematic is to reduce geometrical deviations of the holes and defects during manufacturing. The interaction between a laser beam and an absorbent metallic matter in the laser drilling regime involves thermal and hydrodynamical phenomenon. Their role on the drilling is not yet completely understood and a realistic simulation of the process could contribute to a better understanding of these phenomenon. The simulation of such process induces strong numerical difficulties. This work presents a physical model combined with the use of the original Constraint Natural Element Method to simulate the laser drilling. The physical model includes solid/liquid and liquid/vapor phase transformations, the liquid ejection and the convective and conductive thermal exchanges. It is the first time that all these phenomena are included in a modelling and numerically solved in a 2D axisymmmetric problem. Simulations results predict most of measurements (hole geometry, velocity of the liquid ejection and laser drilling velocity) without adjusting any parametersProcédé de perçage par laser : Comparaison entre des données expérimentales et une simulation 2D basée sur la méthode CNEM
http://hdl.handle.net/10985/7637
Procédé de perçage par laser : Comparaison entre des données expérimentales et une simulation 2D basée sur la méthode CNEM
GIRARDOT, Jérémie; SCHNEIDER, Matthieu; ILLOUL, Lounès; BERTHE, Laurent; FAVIER, VERONIQUE; LORONG, Philippe; RANC, Nicolas
This work presents a numerical alternative for the laser drilling simulation problem. Using finite element method is difficult to simulate the hole propagation over time, especially because of moving boundaries due to a fast phase change and high thermal gradients. First, the physical process of the laser drilling and the modeling equations are clarified. Then a comparison between experimental data and simulation outputs regarding the laser peak power is investigated.
Tue, 01 Jan 2013 00:00:00 GMThttp://hdl.handle.net/10985/76372013-01-01T00:00:00ZGIRARDOT, JérémieSCHNEIDER, MatthieuILLOUL, LounèsBERTHE, LaurentFAVIER, VERONIQUELORONG, PhilippeRANC, NicolasThis work presents a numerical alternative for the laser drilling simulation problem. Using finite element method is difficult to simulate the hole propagation over time, especially because of moving boundaries due to a fast phase change and high thermal gradients. First, the physical process of the laser drilling and the modeling equations are clarified. Then a comparison between experimental data and simulation outputs regarding the laser peak power is investigated.Simulation numérique du perçage laser par la méthode C-NEM
http://hdl.handle.net/10985/9956
Simulation numérique du perçage laser par la méthode C-NEM
GIRARDOT, Jérémie; ILLOUL, Lounès; SCHNEIDER, Matthieu; BERTHE, Laurent; FAVIER, VERONIQUE; LORONG, Philippe; RANC, Nicolas
Ces travaux présentent une alternative numérique au problème de simulation du procédé de perçage par laser. L’utilisation des éléments finis pour modéliser la propagation du trou au cours du temps montre des limites face à un problème de frontières mobiles induit par un changement de phase rapide et des forts gradients thermiques. L’utilisation d’un code C-NEM a donc été testé avec comme objectif de résoudre ces difficultés numériques et d’utiliser le fort potentiel de cette méthode originale. Le principe physique du perçage laser sera rappelé et le modèle mathématique choisi pour le modéliser sera précisé. Un cas test de simulation a été réalisé avec les grandeurs physiques du fer pur afin de valider le choix du code C-NEM.
Sun, 01 Jan 2012 00:00:00 GMThttp://hdl.handle.net/10985/99562012-01-01T00:00:00ZGIRARDOT, JérémieILLOUL, LounèsSCHNEIDER, MatthieuBERTHE, LaurentFAVIER, VERONIQUELORONG, PhilippeRANC, NicolasCes travaux présentent une alternative numérique au problème de simulation du procédé de perçage par laser. L’utilisation des éléments finis pour modéliser la propagation du trou au cours du temps montre des limites face à un problème de frontières mobiles induit par un changement de phase rapide et des forts gradients thermiques. L’utilisation d’un code C-NEM a donc été testé avec comme objectif de résoudre ces difficultés numériques et d’utiliser le fort potentiel de cette méthode originale. Le principe physique du perçage laser sera rappelé et le modèle mathématique choisi pour le modéliser sera précisé. Un cas test de simulation a été réalisé avec les grandeurs physiques du fer pur afin de valider le choix du code C-NEM.Simulation of the laser drilling process with the Constraint Natural Element Method
http://hdl.handle.net/10985/9954
Simulation of the laser drilling process with the Constraint Natural Element Method
GIRARDOT, Jérémie; ILLOUL, Lounès; SCHNEIDER, Matthieu; BERTHE, Laurent; FAVIER, VERONIQUE; LORONG, Philippe; RANC, Nicolas
These works present a numerical alternative to the simulation of the laser drilling process. The use of the finite element method to modeling the hole creation during a laser pulse shows difficulties in front of a moving boundary problem. This moving boundary is induced by a fast phase transformation and also by high thermal gradient. The C-NEM (Constraint Natural Element Method) was tested in order to solve these numerical difficulties and to use the high potential of this original method. The physical interaction of the laser drilling will be reminded and the chosen mathematical model will be specified. A simulation was made with the data for pure iron in order to validate the numerical choice.
Sun, 01 Jan 2012 00:00:00 GMThttp://hdl.handle.net/10985/99542012-01-01T00:00:00ZGIRARDOT, JérémieILLOUL, LounèsSCHNEIDER, MatthieuBERTHE, LaurentFAVIER, VERONIQUELORONG, PhilippeRANC, NicolasThese works present a numerical alternative to the simulation of the laser drilling process. The use of the finite element method to modeling the hole creation during a laser pulse shows difficulties in front of a moving boundary problem. This moving boundary is induced by a fast phase transformation and also by high thermal gradient. The C-NEM (Constraint Natural Element Method) was tested in order to solve these numerical difficulties and to use the high potential of this original method. The physical interaction of the laser drilling will be reminded and the chosen mathematical model will be specified. A simulation was made with the data for pure iron in order to validate the numerical choice.Modeling laser drilling in percussion regime using constraint natural element method
http://hdl.handle.net/10985/10594
Modeling laser drilling in percussion regime using constraint natural element method
GIRARDOT, Jérémie; ILLOUL, Lounès; SCHNEIDER, Matthieu; FAVIER, VERONIQUE; LORONG, Philippe; RANC, Nicolas
The laser drilling process is the main process used in machining procedures on aeronautic engines, espe- cially in the cooling parts. The industrial problematic is to reduce geometrical deviations of the holes and defects dur- ing manufacturing. The interaction between a laser beam and an absorbent metallic matter in the laser drilling regime involves thermal and hydrodynamical phenomenon. Their role on the drilling is not yet completely understood and a realistic simulation of the process could contribute to a better understanding of these phenomenon. The simula- tion of such process induces strong numerical difficulties. This work presents a physical model combined with the use of the original Constraint Natural Element Method to simulate the laser drilling. The physical model includes solid/liquid and liquid/vapor phase transformations, the liq- uid ejection and the convective and conductive thermal exchanges. It is the first time that all these phenomena are included in a modelling and numerically solved in a 2D axisymmmetric problem. Simulations results predict most of measurements (hole geometry, velocity of the liquid ejection and laser drilling velocity) without adjusting any parameters.
Thu, 01 Jan 2015 00:00:00 GMThttp://hdl.handle.net/10985/105942015-01-01T00:00:00ZGIRARDOT, JérémieILLOUL, LounèsSCHNEIDER, MatthieuFAVIER, VERONIQUELORONG, PhilippeRANC, NicolasThe laser drilling process is the main process used in machining procedures on aeronautic engines, espe- cially in the cooling parts. The industrial problematic is to reduce geometrical deviations of the holes and defects dur- ing manufacturing. The interaction between a laser beam and an absorbent metallic matter in the laser drilling regime involves thermal and hydrodynamical phenomenon. Their role on the drilling is not yet completely understood and a realistic simulation of the process could contribute to a better understanding of these phenomenon. The simula- tion of such process induces strong numerical difficulties. This work presents a physical model combined with the use of the original Constraint Natural Element Method to simulate the laser drilling. The physical model includes solid/liquid and liquid/vapor phase transformations, the liq- uid ejection and the convective and conductive thermal exchanges. It is the first time that all these phenomena are included in a modelling and numerically solved in a 2D axisymmmetric problem. Simulations results predict most of measurements (hole geometry, velocity of the liquid ejection and laser drilling velocity) without adjusting any parameters.