The Experts below are selected from a list of 87 Experts worldwide ranked by ideXlab platform

P. Picart - One of the best experts on this subject based on the ideXlab platform.

  • Identification of the bulk behavior in the near-contact-surface of steel workpieces
    Journal of Materials Engineering and Performance, 1996
    Co-Authors: A Dubois, P. Picart, L Dubar, J Oudin
    Abstract:

    Originally dedicated to the characterization of the material surface properties for processes involving extended workpieces such as tube drawing, the upsetting- sliding test involves a circular cross- section indenter which creates a localized plastic strain by sliding with a given penetration along a Generator Line of a specimen. The mechanical characteristics of the indenter are the same as those of the tool in the fullscale problem, and the specimen is directly extracted from the workpiece or from the target part of the production plant. An analysis of the upsetting phase of the test is proposed to identify the specimen bulk properties in the near- surface. The stress- strain curve of the specimen is averaged by a Ludwik’s model. A dichotomizing search is involved to compute the most suitable Ludwik’s parameters by minimizing the error made between experimental results and elastoplastic finite element computations. Identifications carried out on a 1522 annealed steel specimen accurately determined the bulk behavior.

  • Optimization of the upsetting-sliding test parameters for the determination of friction laws at medium and high contact pressures
    Journal of Materials Processing Technology, 1996
    Co-Authors: André Dubois, D. Patalier, P. Picart, Jérôme Oudin
    Abstract:

    Abstract The upsetting-sliding test is dedicated to the determination and identification of constitutive friction laws. This test originally involved an incLined front face indenter creating a localized plastic zone by moving with a given penetration along a Generator Line of a specimen. The mechanical characteristics of the indenter are the same as those of the contractor or the tool used in the forming sequence studied. In order to propose a larger range of possibilities in the analysis and application of the test results, a new circular cross-sectional indenter profile has been designed. Three-dimensional elasto-plastic finite-element analyses are run to compute the contact pressure, friction stress and effective plastic strain so that an initial guide in the choice of the indenter radius and penetration can be proposed to produce the most realistic conditions of contact in regard to the process studied.

  • Elastoplastic finite element analyses of an upsetting-sliding test for the determination of friction at medium and high contact pressure
    Tribology International, 1996
    Co-Authors: André Dubois, J. Qudin, P. Picart
    Abstract:

    The upsetting-sliding test is a friction test employed for the determination of the tangential stress-contact pressure relationship at a specimen-tool or target part-contactor contact surface. It is used in addition to the analysis of forming sequences or mechanical design. The specimen, or target part, used in the test is the same that the one involved in the studied forming sequence so that the physical and chemical characteristics of the contact involved by the test and sequence are the same. In the test, the contact pressure is exerted by an incLined front surface indenter which takes the place of the tool or the contactor. Then, the indenter is moved in contact with the Generator Line surface of the specimen or the target part. The computation of the tangential stress, contact pressure and effective plastic strain firstly with respect to the penetration, sizing length and front face angle and, secondly, with respect to the frictional variations are performed with a three-dimensional finite element model. An initial guide for the determination of the indenter length and front angle and indenter penetration in the specimen is proposed in order to define the most realistic tangential stress-contact pressure curves.

André Dubois - One of the best experts on this subject based on the ideXlab platform.

  • Optimization of the upsetting-sliding test parameters for the determination of friction laws at medium and high contact pressures
    Journal of Materials Processing Technology, 1996
    Co-Authors: André Dubois, D. Patalier, P. Picart, Jérôme Oudin
    Abstract:

    Abstract The upsetting-sliding test is dedicated to the determination and identification of constitutive friction laws. This test originally involved an incLined front face indenter creating a localized plastic zone by moving with a given penetration along a Generator Line of a specimen. The mechanical characteristics of the indenter are the same as those of the contractor or the tool used in the forming sequence studied. In order to propose a larger range of possibilities in the analysis and application of the test results, a new circular cross-sectional indenter profile has been designed. Three-dimensional elasto-plastic finite-element analyses are run to compute the contact pressure, friction stress and effective plastic strain so that an initial guide in the choice of the indenter radius and penetration can be proposed to produce the most realistic conditions of contact in regard to the process studied.

  • Elastoplastic finite element analyses of an upsetting-sliding test for the determination of friction at medium and high contact pressure
    Tribology International, 1996
    Co-Authors: André Dubois, J. Qudin, P. Picart
    Abstract:

    The upsetting-sliding test is a friction test employed for the determination of the tangential stress-contact pressure relationship at a specimen-tool or target part-contactor contact surface. It is used in addition to the analysis of forming sequences or mechanical design. The specimen, or target part, used in the test is the same that the one involved in the studied forming sequence so that the physical and chemical characteristics of the contact involved by the test and sequence are the same. In the test, the contact pressure is exerted by an incLined front surface indenter which takes the place of the tool or the contactor. Then, the indenter is moved in contact with the Generator Line surface of the specimen or the target part. The computation of the tangential stress, contact pressure and effective plastic strain firstly with respect to the penetration, sizing length and front face angle and, secondly, with respect to the frictional variations are performed with a three-dimensional finite element model. An initial guide for the determination of the indenter length and front angle and indenter penetration in the specimen is proposed in order to define the most realistic tangential stress-contact pressure curves.

Liu Xiaoxi - One of the best experts on this subject based on the ideXlab platform.

  • Research on Multifunctional High-Power Grid Source Simulator System with Synchronous Generator, Line Impedance Imitation, and ZIP Load Emulator
    Energies, 2019
    Co-Authors: Hong Zhu, Xing Zhang, Liu Xiaoxi
    Abstract:

    As the penetration of distributed power sources in the power grid is getting higher and higher, the adverse effects are also increasing. It is necessary to adopt control technology to make the distributed power source participate in the power regulation of the power system. In this paper, a multifunctional high-power grid source simulator system is presented. For wider control bandwidth and better performance, a high-power, back-to-back converter and an auxiliary lower-power, back-to-back converter connected in cascade mode topology is proposed in this paper. The basic principle and implementation method of virtual synchronous Generator (VSG) in the high-power, back-to-back converter are described to reflect the same power frequency characteristics and voltage regulation characteristics as synchronous Generators. Amplitude closed-loop control is proposed to realize zero steady-state error in the lower-power, back-to-back converter, also with Line impedance imitation. Meanwhile, a constant-impedance, constant-current, and constant-power (ZIP) load model is used to emulate static load in the grid simulator system. At last, a set of experimental results for a 2 MW grid simulator system is provided to verify the effectiveness and validity of the proposed approach.

Jérôme Oudin - One of the best experts on this subject based on the ideXlab platform.

  • Optimization of the upsetting-sliding test parameters for the determination of friction laws at medium and high contact pressures
    Journal of Materials Processing Technology, 1996
    Co-Authors: André Dubois, D. Patalier, P. Picart, Jérôme Oudin
    Abstract:

    Abstract The upsetting-sliding test is dedicated to the determination and identification of constitutive friction laws. This test originally involved an incLined front face indenter creating a localized plastic zone by moving with a given penetration along a Generator Line of a specimen. The mechanical characteristics of the indenter are the same as those of the contractor or the tool used in the forming sequence studied. In order to propose a larger range of possibilities in the analysis and application of the test results, a new circular cross-sectional indenter profile has been designed. Three-dimensional elasto-plastic finite-element analyses are run to compute the contact pressure, friction stress and effective plastic strain so that an initial guide in the choice of the indenter radius and penetration can be proposed to produce the most realistic conditions of contact in regard to the process studied.

Hong Zhu - One of the best experts on this subject based on the ideXlab platform.

  • Research on Multifunctional High-Power Grid Source Simulator System with Synchronous Generator, Line Impedance Imitation, and ZIP Load Emulator
    Energies, 2019
    Co-Authors: Hong Zhu, Xing Zhang, Liu Xiaoxi
    Abstract:

    As the penetration of distributed power sources in the power grid is getting higher and higher, the adverse effects are also increasing. It is necessary to adopt control technology to make the distributed power source participate in the power regulation of the power system. In this paper, a multifunctional high-power grid source simulator system is presented. For wider control bandwidth and better performance, a high-power, back-to-back converter and an auxiliary lower-power, back-to-back converter connected in cascade mode topology is proposed in this paper. The basic principle and implementation method of virtual synchronous Generator (VSG) in the high-power, back-to-back converter are described to reflect the same power frequency characteristics and voltage regulation characteristics as synchronous Generators. Amplitude closed-loop control is proposed to realize zero steady-state error in the lower-power, back-to-back converter, also with Line impedance imitation. Meanwhile, a constant-impedance, constant-current, and constant-power (ZIP) load model is used to emulate static load in the grid simulator system. At last, a set of experimental results for a 2 MW grid simulator system is provided to verify the effectiveness and validity of the proposed approach.