Development of a maximum entropy approach for the thermomecanical modelling of the rotary friction welding process

A multi-physics modelling of rotary friction welding process based on a Maximum Entropy approach is proposed. This approach will be able to solve coupled thermomechanical problems. Because strains are very high locally around the welded area, the remeshing time in a classical finite element method is very important. The use of this meshless method should reduce simulations time and the numerical diffusion phenomena

Material Constitutive Behavior Identification at High Strain Rates Using a Direct-Impact Hopkinson Device

Modern numerical simulation techniques allow nowadays obtaining accurate solutions of magnetic pulse and electrohydraulic forming/welding processes. However, one major difficulty persists: the identification of material constitutive equations behavior at levels of high strain rates reached by these processes, and which varies between 103 and 105 s-1. To address this challenge, a direct-impact Hopkinson system was developed at ECN. It permits to perform dynamic tests at very high strain rates exceeding the range of the traditional Split Hopkinson Pressure Bars and hence enable us to identify constitutive models for a wide range of strain rates. The alloy used to test this device was Ti-6Al-4V. Strain rates up to 2.5×103 s-1 were attained

Simulation de l'écoulement des pâtes cimentaires par un modèle diphasique

La modélisation de l'écoulement des pâtes cimentaires est un problème difficile car le matériau a non seulement un comportement rhéologique complexe mais il peut également présenter des hétérogénéités induites par l'écoulement. L'apparition de ces hétérogénéités résulte de la filtration de phases fluides au travers de phases solides et peut conduire au blocage de l'écoulement. Pour modéliser l'écoulement d'un tel matériau il est nécessaire de prendre en compte la présence d'au moins deux phases. Dans notre modélisation nous considérons que les deux phases sont continues et admettent un comportement rhéologique en loi de puissance. Le couplage entre les deux phases est pris en compte au moyen d'une loi de Darcy généralisée à un fluide en loi de puissance. Le modèle est résolu par la méthode des éléments finis et validé dans le cas d'un test d'écrasement. Nous montrons que ces simulations permettent d'établir des diagrammes d'ouvrabilité des pâtes cimentaires

Un Modéle Thermodynamique de Fluide Electro-Rhéologique

none3G. NAPOLI; DROUOT R; RACINEUX GNapoli, Gaetano; Drouot, R; Racineux, G

Development of a maximum entropy approach for the thermomecanical modelling of the rotary friction welding process

A multi-physics modelling of rotary friction welding process based on a Maximum Entropy approach is proposed. This approach will be able to solve coupled thermomechanical problems. Because strains are very high locally around the welded area, the remeshing time in a classical finite element method is very important. The use of this meshless method should reduce simulations time and the numerical diffusion phenomena

Modélisation du comportement électromécanique des suspensions électrorhéologiques en traction-compression

none3G. NAPOLI; DROUOT R; RACINEUX GNapoli, Gaetano; Drouot, R; Racineux, G

Continuum Modelling of Electrorheological Fluids

none3DROUOT R; G. NAPOLI; RACINEUX GDrouot, R; Napoli, Gaetano; Racineux, G

Annales de la Fondation Louis de Broglie

RÉSUMÉ. Les déchargesélectriques effectuées avec des fils de titane dans de l'eau créent des monopôles magnétiques. Ceux-ci sont visibles directement ou indirectement par leur action sur des plaques photographiques ou dans les poudres issues des tirs. Ce sont ces effets directs et indirects qui sont passés en revue ici ABSTRACT: Electrical explosions of a titanium wire in water create magnetic monopoles. They are seen directly or indirectly by their effects on photographic plates or by properties of powders resulting from the electrical discharge. These direct and indirect effects are reviewed. We report here results obtained from the trials done at Ecole Centrale de Nantes, comparing with the result of experiments conducted by L. Urutskoev. To be close to his work, our electrical discharges were performed on titanium wires in water. The discharge causes the creation of a plasma and a shock wave, and hence the device is installed within a metal enclosure (Stainless steel /Aluminum) to avoid radiation effects. The device is protected from the discharge by having a polyurethane insulation. This insulation has been covered with a 2 mm layer of Teflon for security measures. The only metal present within this metal enclosure is the Ti40, a high quality titanium. This setup was explained in a previous report of our work [1]. The results must be regarded as partial, provisional. They may be increased if the necessary improvements can be made. However, these results seem sufficiently important from a scientific point of view for us to present them. Direct observation of magnetic monopoles and their traces on film are reported in [2], in this article, we describe our other results