21 research outputs found

    Collective Quadrupole Behavior in \u3csup\u3e106\u3c/sup\u3ePd

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    Excited states in 106Pd were studied with the (n,n′γ) reaction, and comprehensive information for excitations with spin ≤6ℏ was obtained. The data include level lifetimes in the femtosecond regime, spins and parities, transition multipolarities, and multipole mixing ratios, which allow the determination of reduced transition probabilities. The E2 decay strength to the low-lying states is mapped up to ≈2.4 MeV in excitation energy. The structures associated with quadrupole collectivity are elucidated and organized into bands

    Effect of Forge Application on Microstructural and Mechanical Properties of AISI 316 Using Direct Drive Friction Welding Process

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    Present study introduces effect of forge application and elimination on microstructural and mechanical properties of AISI 316 during friction welding. Temperature measurements, microstructure, micro-hardness, tensile test, scanning electron microscopy and X-ray diffraction were evaluated. Maximum temperature recorded was 819°C while forge was applied between 357°C-237°C. Thermo-mechanically affected zone and highly plastically deformed zone were created at the interface at elimination and application of forge respectively. Ultimate tensile strength decreased and ductility increased when forge elimination compared to forge application. Tensile fracture was occurred adjacent to the welding interface for both cases, though, after forge application, ductile fracture mode and cleavage features through the fingerprints were observed in the fracture morphology. Redistribution and concentration of gamma iron in 111 level after forge application and heat treated of AISI 316

    DISSOLUTION DANS L’ALLIAGE Al-21at.% Zn DISSOLUTION IN THE Al-21at.% Zn ALLOY

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    Les alliages du système Al-Zn sont très appropries aux cinématiques de la restauration de la phase dans les solutions solides et la dissolution dans ce système a fait l’objet de nombreuses investigations, ayant contribuées à la compréhension des différents mécanismes et cinétiques de cette réaction. Le but de ce travail est la mise en évidence des mécanismes et processus intervenant lors de la dissolution de l’alliage Al-21at. % Zn et les modifications des propriétés mécaniques qui les accompagnent. Les techniques d’analyse utilisées à cet égard sont le microscope optique et la dureté HV. Dissolution in alloy of the system Al-Zn was the subject of many studies, having contributed to comprehensions of the various mechanisms and kinetics of this reaction. The goal of this work is highlighted mechanisms and process intervening during the dissolution of alloy Al-21at.% Zn and the modifications of the mechanical properties which accompany, in particular the hardness then analysis by technical used in this respect are: The optical microscope and hardness Vickers

    Integrity of Pipelines Transporting Hydrocarbons

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    This book describes technical and practical aspects of pipeline damage. It summarizes the phenomena, mechanisms and management of pipeline corrosion in-service. The topics discussed include pipelines fracture mechanics, damage mechanisms and evolution, and pipeline integrity assessment. The concept of acceptable risk is also elucidated and the future application of new knowledge management tools is considered

    Micromechanics-based constitutive modeling of plastic yielding and damage mechanisms in polymer-clay nanocomposites: Application to polyamide-6 and polypropylene-based nanocomposites

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    International audienceThe present work focuses on the continuum-based micromechanical modeling of the elastic-plastic stress-strain response including damage mechanisms of polymer-clay nanocomposites. The micromechanical elastic-plastic-damage model includes both the actual microstructure of the said composites using a multi-scale approach and the microstructural evolution related to damage accumulation under applied macroscopic deformation. The interfacial debonding between clay nanoparticles and polymer matrix, and the polymer matrix voiding are the two prevalent damage events considered. The tensile stress-strain response and micromechanical deformation processes of polyamide-6 and polypropylene-based systems reinforced with modified montmorillonite clay at various concentrations are experimentally investigated by a video-controlled technique. The usual shear yielding deformation mode of neat polyamide-6 is altered by the presence of clay platelets which induce a dilatational process due to interfacial debonding. In addition to matrix shear yielding, a dual-dilatational deformation mechanism by crazing and interfacial debonding is revealed in polypropylene-clay nanocomposites. Using the intrinsic deformation micromechanisms and elastic-plastic properties of the polymer matrix, and the nanocomposite structural characteristics, the micromechanical model is found to successfully describe the experimental results of the two nanocomposite materials in terms of tensile stress-strain response and inelastic volumetric strain
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