Results 1 - 10 of 73
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[en] The paper presents the results of the study aimed at determining the elastoplastic properties of an Al/Cu bimetallic sheet consisting of aluminum and copper layers, which were joined by cold rolling. The values of elasticity coefficients in three orthotropic planes as well as the Kirchhoff modulus, and coefficient of internal friction in the perpendicular direction to the lamination were determined. The subjects of the analysis were also the values of limit stresses, uniform energy of elastic and plastic strain per unit volume, and coefficients of the hardening curve and normal anisotropy. The tests were carried out on bimetallic specimens with varying thicknesses of the copper layer, cut from the Al/Cu sheet in the direction of rolling and in the direction perpendicular to it. Two methods of determining the directional values of mechanical parameters were used in the tests, i.e., the uniaxial quasi-static tensile test and the dynamic acoustic resonance method. It was concluded that these methods made it possible to determine directional elastoplastic properties of the Al/Cu bimetallic sheet taking into account the variable share of components in the bimetal and the direction of cutting out specimens from cold-rolled sheet.
[en] The paper presents a technique for measuring water concentration profiles based on Neutron BackScattering Imaging (NBSI) technique. Using this technique the water concentration profiles have been measured in different types of porous media with rigid solid structure, like soil and concrete samples. The gross moisture content could be determined directly from these profiles and 2D cross-sectional images. The proposed NBSI technique can be used in both stationary and dynamic modes. The obtained results can give reliable data on moisture distribution in the porous bodies, as a function of position and time. (author).
[en] Widely used structures in an industrial context, such as plates, pipes or rails, can be considered as waveguides. Hence efficient Non Destructive Testing techniques are needed in order to detect defects in these structure during their maintenance. This work is about adapting a sampling method, the Linear Sampling Method, to the context of NDT for elastic waveguides. This context implies that the solicitations and measurements must be on the surface of the waveguide in a time-dependent regime. A modal and multi-frequency formulation of the LSM, specific to waveguides, has been chosen to solve the problem. This formulation allows an efficient and physical regularization of the inverse problem, which is naturally ill-posed. An optimization of the number of sources and measurements and of their positioning is possible thanks to the methodology used to solve the problem. The scalar case of an acoustic waveguide is considered as a first step, while the vectorial case of an elastic waveguide, more complex by nature, is addressed in a second time.The efficiency of the method is at first tested on artificial data (numerically made), and then on real data obtained from experiments on metallic plates. These experiments show the feasibility of using sampling methods for Non Destructive Testing in an industrial context. In the case when only one solicitation is available, the LSM can not be applied. A completely different approach is then used, which is called the 'exterior' approach, coupling a mixed formulation of quasi-reversibility and a level-set method in order to recover the shape of the defect. (author)
[fr]De nombreuses structures utilisees industriellement peuvent etre considerees comme des guides d'ondes, comme les plaques, les tuyaux ou encore le rails. La maintenance de ces structures necessite de pouvoir detecter efficacement des defauts internes par le Controle Non Destructif. Nous nous interessons dans ce manuscrit a l'application d'une methode d'echantillonnage, la Linear Sampling Method, au CND des guides d'ondes elastiques, qui en particulier impose des sollicitations et des mesures a la surface du guide en regime temporel. La strategie choisie repose sur une formulation modale et multi-frequentielle de la LSM, specifique aux guides d'ondes, qui permet une regularisation efficace et de nature physique du probleme inverse, qui est par nature mal pose. Cette strategie permet par ailleurs une optimisation du nombre et de la position des emetteurs et des recepteurs. Nous nous limitons dans un premier temps au cas scalaire du guide d'ondes acoustiques, pour ensuite s'attaquer au cas vectoriel, et par consequent plus complexe, du guide d'ondes elastiques. L'efficacite de la methode inverse est dans un premier temps demontree sur des donnees artificielles (obtenues numeriquement), puis sur des donnees reelles obtenues a l'aide d'experiences realisees sur des plaques metalliques. Ces experiences confirment la faisabilite du CND par methode d'echantillonnage dans un cadre industriel. Dans le cas ou une seule sollicitation est realisee, l'utilisation de la LSM est exclu. Nous utilisons une approche tout a fait differente et dite 'exterieure', couplant une formulation mixte de quasi-reversibilite et une methode de lignes de niveau, pour reconstruire le defaut.
[en] The authors conducted research to find methods of nondestructive testing for preliminary determination of detonation of thin-layer nanostructured explosives obtained by thermal vacuum sublimation. It was necessary for detecting the relationship between the microstructure and its detonation. It is shown that the specific length of crystals correlates with its detonation and can be used for nondestructive testing of thin-layer nanostructured explosives obtained by thermal vacuum sublimation
[ru]С целью разработки методов неразрущающего контроля для предварительного определения детонационной способности взрывчатых веществ по термовакуумной технологии (ВВ-ТТ) проведено исследование по установлению взаимосвязи между микроструктурой гексогена-ТТ и его детонационной способностью. Показано, что удельная длина границ раздела кристаллов гексогена-ТТ коррелирует с его детонационной способностью и может использоваться для неразрушающего контроля ВВ-ТТ
[en] Laser-induced breakdown spectroscopy (LIBS) is an analytical technique allowing the determination of elemental concentrations in a variety of matrices in the solid, liquid, and gaseous phases. Because of the inherent complexity of the signal and to the high dimensionality of experimental data, chemometrics has been more and more applied in LIBS to perform samples identification or quantitative measurements. But multivariate methods can also be used for the description and physical interpretation of the plasma, particularly to exploit the temporal dimension of the LIBS signal, which is usually neglected in spectrochemical measurements. In this work, time-resolved spectra of a pure aluminum sample were treated with 2 methods, mean field-independent components analysis and multivariate curve resolution- alternating least squares, applying non-negativity constraints for scores and components in both cases. Results obtained were compared with reference univariate measurements of the emission of the species of interest (ions, neutral atoms, and molecules). The interpretation of scores and components provided a physical description of phenomena that take place between species in the plasma, like ionic recombination and molecules formation. Overall, mean field-independent components analysis and multivariate curve resolution-alternating least squares yield equivalent solutions with our dataset. This new approach is very promising for the treatment of time-resolved data obtained by LIBS. (authors)
[en] Plants are constantly challenged when trying to examine hard-to-reach areas. Execution of inspections during outages, where time pressure is an issue, calls for rapid performance without compromising precision and reliability. Inside NDE of primary piping especially for smaller diameters requires dedicated solutions. Combining long-term experience in remote-operated crawlers with expert knowledge in nondestructive examination (NDE) Framatome provides various technologies for inspection of hardly accessible areas. In-pipe manipulators have several advantages for flexible application in vertical or horizontal piping including elbows. The paper will give an overview on the present in-pipe manipulator development for pipe ID 75 to 110 mm. Focus is on the capabilities and features for visual inspection (VT), eddy-current (ECT) and ultrasonic testing (UT) as well as result assessment. (author)
[en] The distance of control area and supervision area for the on-site inspection operation of X-ray mobile device is calculated in this paper. The distance of control area and supervise area were respectively given for scattered X-ray, transmission X-ray, leakage X-ray. The influence on the radiation environment of transmission X-ray is the greatest, followed by scattering X-ray. The influence of leakage X-ray is the lowest. In the end, the radiation protection measures for on-site operation of X-ray detector are discussed and suggestions are given. (authors)
[en] Non-destructive tests (NDT) have been used in the last decades for the assessment of in-situ quality and integrity of concrete elements. An important step in the application of NDT methods concerns to the interpretation and validation of the test results. In general, interpretation of NDT results should involve three distinct phases leading to the development of conclusions: processing of collected data, analysis of within-test variability and quantitative evaluation of property under investigation. The analysis of within-test variability can provide valuable information, since this can be compared with that of within-test variability associated with the NDT method in use, either to provide a measure of the quality control or to detect the presence of abnormal circumstances during the in-situ application. This paper reports the analysis of the experimental results of within-test variability of NDT obtained for normal vibrated concrete and self-compacting concrete. The NDT reported includes the surface hardness test, ultrasonic pulse velocity test, penetration resistance test, pull-off test, pull-out test and maturity test. The obtained results are discussed and conclusions are presented. (paper)
[en] SNC-Lavalin Nuclear has developed a next-generation portable cable indenter for measurement of indenter modulus in accordance with international standard IEC/IEEE 62582-2 and for measurement of recovery time. The tool is based on a prototype initially developed by Atomic Energy of Canada Ltd. with enhancements to the usability and ergonomics of the instrument. Recovery Time shows more sensitivity to cable degradation than Indenter Modulus for several cable jacket and insulation materials, including irradiated PVC, thermally aged CSPE, and irradiated/thermally aged XLPE. SNC-Lavalin collaborated with Canadian Nuclear Laboratories to qualify the tool and develop a cable database. Operating experience(OPEX) from field trial at a Nuclear Generating Station was incorporated into the design. The Advanced Portable Polymer Tester (APPT) features single user operation, touch-screen control, consistent automated cable clamping and temperature control, measurement of Indenter Modulus and Recovery Time, improved human factors and immediate preliminary results information post-test. (author)