Qualification of a robotized Friction Stir Welding System

This paper presents an experimental methodology to determine a Friction Stir Welding (FSW) means of production based on the experimental study of the tool / material mechanical interactions generated during the welding operation. These two stages have been identified as being characteristic for the qualification of a FSW equipment. This paper presents the experimental results of the parametric study done on the plunging and welding phases. Ranges of forces and torques diagrams were established according to the processing parameters, in order to qualify a means of production and select the process parameters allowing the operation on the available FSW equipment

Product design-Process selection-Process planning Integration based on Modelling and Simulation

As a solution for traditional design process having many drawbacks in the manufacturing process, the integration of Product design-Process selection-Process planning is carried out in the early design phase. The technological, economic, and logistic parameters are taken into account simultaneously as well as manufacturing constraints being integrated into the product design. As a consequence, the most feasible alternative with regard to the product’s detailed design is extracted satisfying the product’s functional requirements. Subsequently, a couple of conceptual process plans are proposed relied on manufacturing processes being preliminarily selected in the conceptual design phase. Virtual manufacturing is employed under CAM software to simulate fabrication process of the potential process plans. Ultimately, the most suitable process plan for fabricating the part is recommended based upon a multi-criteria analysis as a resolution for decision making

Determining the ability of a high payload robot to perform FSW applications

This paper presents an experimental methodology to determine a Friction Stir Welding (FSW) means of production based on the experimental study of the tool / material mechanical interactions generated during the welding operation. These two stages have been identified as being characteristic for the qualification of a FSW equipment. This paper presents the experimental results of the parametric study done on the plunging and welding phases. Ranges of forces and torques diagrams were established according to the processing parameters, in order to qualify a means of production and to select the processing parameters allowing the operation on the available FSW equipment

Feasibility and effect of in-home physical exercise training delivered via telehealth before bariatric surgery

Abstract : Optimal physical activity (PA) interventions are needed to increase PA in individuals with severe obesity, and optimize the results of bariatric surgery (BS). The aim of this study was to assess the feasibility and effect of in-home Pre-Surgical Exercise Training delivered via telehealth (TelePreSET) in subjects awaiting BS. Six women following the TelePreSET were compared to the women from a previous study (12 performing the PreSET in a gymnasium and 11 receiving usual care). In-home TelePreSET (12-weeks of endurance and strength training) was supervised twice weekly using videoconferencing. Physical fitness, quality of life, exercise beliefs, anthropometric measures, and telehealth perception were assessed before and after 12-weeks. Satisfaction was evaluated with questionnaires at the end of the intervention. The TelePreSET participants attended 96 % of the exercise sessions, and were very satisfied by the TelePreSET. The baseline telehealth perception score was high, and increased significantly after the intervention. The TelePreSET group significantly increased their physical fitness compared to the usual care group. No significant change was noted in other outcomes. The TelePreSET is feasible and seems effective to improve the physical fitness of women awaiting BS. Further studies will confirm beneficial effects of this innovative mode of delivery

Methodology for qualifying a Friction Stir Welding equipment

The objective of this research work is the industrialization of the friction stir welding process in order to provide tools to industrials to select and qualify a machine for their FSW applications. This paper presents a methodology to determine the Friction Stir Welding equipment adequate to an application. The adequate equipment can be every machine that can perform friction stir welds. This paper presents a short review, based on literature survey, of the existing friction stir welding equipments. Then, the methodology developed is presented. It is based on the studying of the interactions between the tool and the workpiece

FSW : UN PROCEDE DE SOUDAGE POUR LES ALLIAGES D’ALUMINIUM DE FONDERIE

L’étude présentée concerne la réalisation d’un démonstrateur mettant en évidence le potentiel du procédé de soudage par friction malaxage ( FSW) pour la reconception et la réalisation de pièce en alliages d’aluminium de fonderie. Le potentiel du FSW vient en grande partie du fait que la matière n’atteint pas la fusion lors de l’élaboration de la soudure. Ceci permet notamment de souder des alliages sensibles à la fissuration à chaud et de réaliser des assemblages hétérogènes. La reconception du produit doit tenir compte des contraintes du FSW. Ces dernières ont été identifiées et correspondent à la nécessité de contenir la matière lors du malaxage. Ceci se traduit par une contrainte d’accessibilité de l’outil à la soudure, de celle d’une enclume à l’envers de la soudure et à la présence de matière en épaisseur suffisante autour du pion. Une autre contrainte vient des efforts générés lors du soudage. Les géométries conçues doivent permettre la réalisation d’un montage de soudage supportant les efforts de soudage. L’étude particulière de l’une des soudures du démonstrateur a permis de mettre en évidence la relative tolérance du FSW au défaut de mise en position des pièces à souder et de suivi de trajectoire

Fast pyrolysis of Miscanthus x Giganteus in an IR heated reactor

International audienceIntensive research on Miscanthus x Giganteus (MG), a large perennial grass, has been achieved in the last ten years because of its known advantages for farmers (high yield, low input, perennial crop, easy harvesting…) [refs 1,2,3,4]. MG is often considered as a good candidate to produce renewable energy. As lignocellulosic feedstock, MG could also serve to produce chemicals. This approach is far less present in the literature. Because logistics costs could affect the attractiveness of MG, pyrolysis is an interesting technology for energy densification [ref 4]. Therefore the present work describes the pyrolysis of Miscanthus x Giganteus. It is well know that pyrolysis products are solids, liquids and gas. Low residence time, enhanced by high heating rates and high flow rates, favors the production of liquids. A temperature range between 450 and 550°C is also recommended to limit gas formation. A new pyrolysis apparatus designed to achieve fast pyrolysis via infrared heating and low residence time is described. Process conditions are varied for temperature, particle size, N 2 flow rate and preheating effect. Pyrolysis temperature should be the most influential parameter upon the yield and properties of bio-oil. Tests are performed at different levels of power and duration. Temperature is measured in the border and in the center of the reactor because of the presence of radial gradients. The highest bio-oil yield and corresponding temperature profiles are presented. The effect of process conditions on bio-oil yield is assessed. The bio-oil composition is analyzed by GCMS. The results are compared with a direct analysis of MG by Py-GCMS. The bio char is characterized in terms of calorific value with respect to the raw MG High Heating Value (HHV). Furthermore, on the one hand the outlet gas composition is analyzed by online infrared spectroscopy which gives an indication of potential use as secondary source of energy. On the other hand the porosity of the bio-solid products is estimated by BET low-temperature adsorption method for further valorization purpose of pyrolysis products. Highlights: 1) New experimental results on Miscanthus x Giganteus pyrolysis are presented. 2) Characterization of every product thus resource potential is evaluated. 3) Comparison of Py-GCMS with lab scale pyrolysis of MG is performed. References: 1) Anissa Khelfa, Victor Sharypov, Gisèle Finqueneisel, Jean Victor Weber J. Anal. Appl. Pyrolysis 84 (2009) 84–88, Catalytic pyrolysis and gasification of Miscanthus Giganteus: Haematite (Fe2O3) a versatile catalyst

Démarche pour le choix et/ou la conception d’un moyen de soudage par FSW

Les travaux de recherches présentés concernent l'industrialisation du procédé de soudage par friction malaxage, également appelé Friction Stir Welding (FSW). L'objectif est de fournir des outils aux industriels pour choisir et qualifier une machine pour leurs applications de FSW. Cet article présente une méthodologie pour qualifier et / ou concevoir les moyens de soudage adaptés à une application donnée. La démarche de qualification repose sur l’étude géométrique des pièces et sur l’analyse des actions mécaniques transmises par l’outil au travers les domaines de soudabilités. La démarche globale est présentée à l’aide du formalisme IDEF0.The objective of the presented research work is the industrialization of the friction stir welding process in order to provide tools to industrials to select and qualify a means of production for their FSW applications. This paper presents a methodology to determine the Friction Stir Welding means of production adequate to an application. The methodology is based on the analysis of the workpiece geometries and the analysis of the process forces and torqus generated during welding through the determination of the process windows. In this paper, the means of production determination method is presented thanks the IDEF0 formalism

Application aux pièces en alliages d’aluminium moulés

Le soudage par friction malaxage (FSW) est un procédé de soudage de proche en proche à l’état solide. Ceci permet d’éviter la formation de certains défauts apparaissant lors de la solidification en soudage par fusion comme les fissures à chaud ou les soufflures. Dans le cas des alliages d’aluminium, ceci offre de grandes possibilités comme le soudage des alliages des séries 2000 (Al-Cu) et 7000 (Al-Zn) ainsi que les alliages de fonderie. En FSW, l’énergie de soudage est produite par le travail de l’interaction mécanique entre un outil et les pièces à assembler. La matière localement malaxée doit rester confinée autour de l’outil. Ces deux derniers points vont contraindre la conception des pièces à assembler et la gamme de soudage. Cet article présente les premiers résultats d’une étude du potentiel du FSW pour la réalisation de pièce de forme complexe, traditionnellement obtenue en fonderie. Ce travail n’aborde pas la reconception de produit mais traite des gammes de fabrication et de soudage en mettant en évidence les avantages et contraintes du procédé. Une démarche de conception de la gamme de soudage est proposée

Tensor Perturbations in Quantum Cosmological Backgrounds

In the description of the dynamics of tensor perturbations on a homogeneous and isotropic background cosmological model, it is well known that a simple Hamiltonian can be obtained if one assumes that the background metric satisfies Einstein classical field equations. This makes it possible to analyze the quantum evolution of the perturbations since their dynamics depends only on this classical background. In this paper, we show that this simple Hamiltonian can also be obtained from the Einstein-Hilbert lagrangian without making use of any assumption about the dynamics of the background metric. In particular, it can be used in situations where the background metric is also quantized, hence providing a substantial simplification over the direct approach originally developed by Halliwell and Hawking.Comment: 24 pages, JHEP forma