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Daniel Broc - One of the best experts on this subject based on the ideXlab platform.

  • A Homogenisation Method for a FSI Problem: Application to a Tube Bundle Row
    Volume 5: High-Pressure Technology; ASME Nondestructive Evaluation Diagnosis and Prognosis Division (NDPD); SPC Track for Senate, 2017
    Co-Authors: Gianluca Artini, Daniel Broc
    Abstract:

    A research program is ongoing at CEA in the framework of ASTRID project, for developing and validating tools for the analysis of the mechanical dynamic behaviour of Fast Breeder Reactor (FBR) cores. In this context, Fluid Structure Interaction is a recurring problem, especially in case of tube bundles in nuclear reactor cores or steam generators. The large number of elements makes modelling difficult to perform and any direct numerical simulation at whole core scale unachievable. In order to overcome this limitation, we resort to Homogenisation techniques which allow to describe the global dynamic behaviour of the whole fluid-structure system. The purpose of this study is to better understand the effects of the spatial variation of the tube displacement field on the whole bundle dynamics. Thanks to multiple scales, a complete development of the problem is conducted. An analysis of the effects of spatial variations of the long scale displacement field on the tube bundle’s dynamics is led. As a first step we consider the Homogenisation of Euler linear equations that gives us the possibility to make a thorough assessment of the problem with the extension to follow to Navier-Stokes equations.Copyright © 2017 by ASME

  • Homogenisation Method for the dynamic analysis of a complete nuclear steam generator with fluid structure interaction
    Nuclear Engineering and Design, 2008
    Co-Authors: Jean François Sigrist, Daniel Broc
    Abstract:

    Abstract The present paper deals with the dynamic analysis of a steam generator tube bundle with fluid–structure interaction modelling. As the coupled fluid–structure problem involves a huge number of degrees of freedom to account for the tube displacements and the fluid pressure evolutions, classical coupled Method cannot be applied for industrial studies. In the present case, the three-dimensional fluid–structure problem is solved with an Homogenisation Method, which has been previously exposed and successfully validated for FSI modelling in a nuclear reactor [Sigrist, J.F., Broc, D., 2007a. Homogenisation Method for the modal analysis of a nuclear reactor with internal structures modelling and fluid–structure interaction coupling. Nuclear Engineering and Design 237, 431–440]. Formulation of the Homogenisation Method for general two- and three-dimensional cases is exposed in the paper. Application to a simplified, however representative, model of an actual industrial nuclear component (steam generator) is proposed. The problem modelling, which includes tube bundle, primary and secondary fluids and pressure vessel, is performed with an engineering finite element code in which the Homogenisation technique has been implemented. From the practical point of view, the analysis highlights the major fluid–structure interaction effects on the dynamic behaviour of the steam generator; from the theoretical point of view, the study demonstrates the efficiency of the Homogenisation Method for periodic fluid–structure problems modelling in industrial configurations.

  • Homogenisation Method for the modal analysis of tube bundle with fluid structure interaction modelling
    Finite Elements in Analysis and Design, 2008
    Co-Authors: Jean François Sigrist, Daniel Broc
    Abstract:

    The present paper is concerned with the modal analysis of a two-dimensional tube bundle with fluid-structure interaction (FSI) modelling. The numerical modelling of FSI effects is performed with a Homogenisation approach, using a Method whose principles have been presented in a previous paper for the modal analysis of a nuclear reactor with internal structures and FSI modelling [J.F. Sigrist, D. Broc, Homogenisation Method for the modal analysis of a nuclear reactor with internal structures modelling and fluid structure-interaction coupling, Nucl. Eng. Des. 237 (2007) 431-440]. The Method is adapted here in the case of tube bundle and compared with the classical approach, based on a direct finite element discretisation of the coupled problem with all tubes modelling. The theoretical background of the Method is recalled, the numerical implementation in a finite element code is exposed and a comparison of the ''Homogenisation'' and ''coupled'' Methods is proposed in the case of a 10x10 tube bundle. Calculation of eigenmode shapes, frequencies and effective masses with the two Methods is performed; it is concluded that: (i) the computational time is significantly lowered when using the Homogenisation Method instead of the coupled Method, since the problem size is reduced by 90%; (ii) the tube bundle dynamic is described in a space-averaged manner, which is sufficient to account for the main inertial coupling effects. Extension of the Method to a three-dimensional case can now be considered; implementation of the Method in a commercial finite element code is also currently investigated.

  • dynamic analysis of a tube bundle with fluid structure interaction modelling using a Homogenisation Method
    Computer Methods in Applied Mechanics and Engineering, 2008
    Co-Authors: Jean François Sigrist, Daniel Broc
    Abstract:

    Abstract The present paper is concerned with the dynamic analysis of a tube bundle with fluid–structure interaction (FSI) modelling. Modelling of FSI is performed with a Homogenisation approach which is compared with the classical coupled approach; this latter is based on a direct finite element discretisation of the coupled problem with all tubes modelling, while the former lies on a description of the fluid–tubes system through an equivalent continuous medium, characterised by a set of dynamic equations which describe the behaviour of the tubes and the fluid from a global point of view. Theoretical background of the Method is recalled, numerical implementation in a finite element code is exposed and comparison of the “Homogenisation” and “coupled” Method is proposed in the case of a 10 × 10 tube bundle, in 2D and 3D configurations. Calculation of eigenmode shapes, frequencies and effective masses with the two Methods is performed, as well as the dynamic response of the coupled system subjected to seismic loading. It is concluded that: (i) the computational time are significantly lowered when using the Homogenisation Method instead of the coupled Method, since the problem size is reduced by 90%; (ii) the tube bundle dynamic is described in a space-averaged manner, which is sufficient to account for the main inertial coupling effects: no significant discrepancies are reported in the modal and dynamic analysis, when performed with the Homogenisation and the coupled approaches, which makes the proposed Method of practical interest for future engineering applications.

  • Homogenisation Method for the modal analysis of tube bundle with fluid-structure interaction modelling
    Finite Elements in Analysis and Design, 2008
    Co-Authors: Jean François Sigrist, Daniel Broc
    Abstract:

    The present paper is concerned with the modal analysis of a two-dimensional tube bundle with fluid-structure interaction (FSI) modelling. The numerical modelling of FSI effects is performed with a Homogenisation approach, using a Method whose principles have been presented in a previous paper for the modal analysis of a nuclear reactor with internal structures and FSI modelling [J.F. Sigrist, D. Broc, Homogenisation Method for the modal analysis of a nuclear reactor with internal structures modelling and fluid structure-interaction coupling, Nucl. Eng. Des. 237 (2007) 431-440]. The Method is adapted here in the case of tube bundle and compared with the classical approach, based on a direct finite element discretisation of the coupled problem with all tubes modelling. The theoretical background of the Method is recalled, the numerical implementation in a finite element code is exposed and a comparison of the ''Homogenisation'' and ''coupled'' Methods is proposed in the case of a 10x10 tube bundle. Calculation of eigenmode shapes, frequencies and effective masses with the two Methods is performed; it is concluded that: (i) the computational time is significantly lowered when using the Homogenisation Method instead of the coupled Method, since the problem size is reduced by 90%; (ii) the tube bundle dynamic is described in a space-averaged manner, which is sufficient to account for the main inertial coupling effects. Extension of the Method to a three-dimensional case can now be considered; implementation of the Method in a commercial finite element code is also currently investigated.

Jean François Sigrist - One of the best experts on this subject based on the ideXlab platform.

  • Homogenisation Method for the dynamic analysis of a complete nuclear steam generator with fluid structure interaction
    Nuclear Engineering and Design, 2008
    Co-Authors: Jean François Sigrist, Daniel Broc
    Abstract:

    Abstract The present paper deals with the dynamic analysis of a steam generator tube bundle with fluid–structure interaction modelling. As the coupled fluid–structure problem involves a huge number of degrees of freedom to account for the tube displacements and the fluid pressure evolutions, classical coupled Method cannot be applied for industrial studies. In the present case, the three-dimensional fluid–structure problem is solved with an Homogenisation Method, which has been previously exposed and successfully validated for FSI modelling in a nuclear reactor [Sigrist, J.F., Broc, D., 2007a. Homogenisation Method for the modal analysis of a nuclear reactor with internal structures modelling and fluid–structure interaction coupling. Nuclear Engineering and Design 237, 431–440]. Formulation of the Homogenisation Method for general two- and three-dimensional cases is exposed in the paper. Application to a simplified, however representative, model of an actual industrial nuclear component (steam generator) is proposed. The problem modelling, which includes tube bundle, primary and secondary fluids and pressure vessel, is performed with an engineering finite element code in which the Homogenisation technique has been implemented. From the practical point of view, the analysis highlights the major fluid–structure interaction effects on the dynamic behaviour of the steam generator; from the theoretical point of view, the study demonstrates the efficiency of the Homogenisation Method for periodic fluid–structure problems modelling in industrial configurations.

  • Homogenisation Method for the modal analysis of tube bundle with fluid structure interaction modelling
    Finite Elements in Analysis and Design, 2008
    Co-Authors: Jean François Sigrist, Daniel Broc
    Abstract:

    The present paper is concerned with the modal analysis of a two-dimensional tube bundle with fluid-structure interaction (FSI) modelling. The numerical modelling of FSI effects is performed with a Homogenisation approach, using a Method whose principles have been presented in a previous paper for the modal analysis of a nuclear reactor with internal structures and FSI modelling [J.F. Sigrist, D. Broc, Homogenisation Method for the modal analysis of a nuclear reactor with internal structures modelling and fluid structure-interaction coupling, Nucl. Eng. Des. 237 (2007) 431-440]. The Method is adapted here in the case of tube bundle and compared with the classical approach, based on a direct finite element discretisation of the coupled problem with all tubes modelling. The theoretical background of the Method is recalled, the numerical implementation in a finite element code is exposed and a comparison of the ''Homogenisation'' and ''coupled'' Methods is proposed in the case of a 10x10 tube bundle. Calculation of eigenmode shapes, frequencies and effective masses with the two Methods is performed; it is concluded that: (i) the computational time is significantly lowered when using the Homogenisation Method instead of the coupled Method, since the problem size is reduced by 90%; (ii) the tube bundle dynamic is described in a space-averaged manner, which is sufficient to account for the main inertial coupling effects. Extension of the Method to a three-dimensional case can now be considered; implementation of the Method in a commercial finite element code is also currently investigated.

  • dynamic analysis of a tube bundle with fluid structure interaction modelling using a Homogenisation Method
    Computer Methods in Applied Mechanics and Engineering, 2008
    Co-Authors: Jean François Sigrist, Daniel Broc
    Abstract:

    Abstract The present paper is concerned with the dynamic analysis of a tube bundle with fluid–structure interaction (FSI) modelling. Modelling of FSI is performed with a Homogenisation approach which is compared with the classical coupled approach; this latter is based on a direct finite element discretisation of the coupled problem with all tubes modelling, while the former lies on a description of the fluid–tubes system through an equivalent continuous medium, characterised by a set of dynamic equations which describe the behaviour of the tubes and the fluid from a global point of view. Theoretical background of the Method is recalled, numerical implementation in a finite element code is exposed and comparison of the “Homogenisation” and “coupled” Method is proposed in the case of a 10 × 10 tube bundle, in 2D and 3D configurations. Calculation of eigenmode shapes, frequencies and effective masses with the two Methods is performed, as well as the dynamic response of the coupled system subjected to seismic loading. It is concluded that: (i) the computational time are significantly lowered when using the Homogenisation Method instead of the coupled Method, since the problem size is reduced by 90%; (ii) the tube bundle dynamic is described in a space-averaged manner, which is sufficient to account for the main inertial coupling effects: no significant discrepancies are reported in the modal and dynamic analysis, when performed with the Homogenisation and the coupled approaches, which makes the proposed Method of practical interest for future engineering applications.

  • Homogenisation Method for the modal analysis of tube bundle with fluid-structure interaction modelling
    Finite Elements in Analysis and Design, 2008
    Co-Authors: Jean François Sigrist, Daniel Broc
    Abstract:

    The present paper is concerned with the modal analysis of a two-dimensional tube bundle with fluid-structure interaction (FSI) modelling. The numerical modelling of FSI effects is performed with a Homogenisation approach, using a Method whose principles have been presented in a previous paper for the modal analysis of a nuclear reactor with internal structures and FSI modelling [J.F. Sigrist, D. Broc, Homogenisation Method for the modal analysis of a nuclear reactor with internal structures modelling and fluid structure-interaction coupling, Nucl. Eng. Des. 237 (2007) 431-440]. The Method is adapted here in the case of tube bundle and compared with the classical approach, based on a direct finite element discretisation of the coupled problem with all tubes modelling. The theoretical background of the Method is recalled, the numerical implementation in a finite element code is exposed and a comparison of the ''Homogenisation'' and ''coupled'' Methods is proposed in the case of a 10x10 tube bundle. Calculation of eigenmode shapes, frequencies and effective masses with the two Methods is performed; it is concluded that: (i) the computational time is significantly lowered when using the Homogenisation Method instead of the coupled Method, since the problem size is reduced by 90%; (ii) the tube bundle dynamic is described in a space-averaged manner, which is sufficient to account for the main inertial coupling effects. Extension of the Method to a three-dimensional case can now be considered; implementation of the Method in a commercial finite element code is also currently investigated.

  • Homogenisation Method for the dynamic analysis of a complete nuclear steam generator with fluid–structure interaction
    Nuclear Engineering and Design, 2008
    Co-Authors: Jean François Sigrist, Daniel Broc
    Abstract:

    The present paper deals with the dynamic analysis of a steam generator tube bundle with fluid–structure interaction modelling. As the coupled fluid–structure problem involves a huge number of degrees of freedom to account for the tube displacements and the fluid pressure evolutions, classical coupled Method cannot be applied for industrial studies. In the present case, the three-dimensional fluid–structure problem is solved with an Homogenisation Method, which has been previously exposed and successfully validated for FSI modelling in a nuclear reactor [Sigrist, J.F., Broc, D., 2007a. Homogenisation Method for the modal analysis of a nuclear reactor with internal structures modelling and fluid–structure interaction coupling. Nuclear Engineering and Design 237, 431–440]. Formulation of the Homogenisation Method for general two- and three-dimensional cases is exposed in the paper. Application to a simplified, however representative, model of an actual industrial nuclear component (steam generator) is proposed. The problem modelling, which includes tube bundle, primary and secondary fluids and pressure vessel, is performed with an engineering finite element code in which the Homogenisation technique has been implemented. From the practical point of view, the analysis highlights the major fluid–structure interaction effects on the dynamic behaviour of the steam generator; from the theoretical point of view, the study demonstrates the efficiency of the Homogenisation Method for periodic fluid–structure problems modelling in industrial configurations.

J.-m. Gatt - One of the best experts on this subject based on the ideXlab platform.

  • Elastic properties of composites: periodical Homogenisation technique and experimental comparison using acoustic microscopy and resonant ultrasonic spectroscopy.
    Ultrasonics, 2006
    Co-Authors: D. Laux, J.-y. Ferrandis, G. Leveque, J.-m. Gatt
    Abstract:

    The macroscopic elastic properties of two composites (Duralumin/air and Duralumin/tungsten carbide (WC)) have been calculated using periodical Homogenisation Methods and the elastic properties of each phase (measured by high frequency acoustic microscopy). In order to check the validity of such an approach, acoustical resonant spectroscopy has also been applied. Thanks to the comparison between the resonant frequencies predicted and measured, two major conclusions have been obtained: the Homogenisation Method is very accurate for the composite Duralumin/air, but not for the Duralumin/WC sample: the experimental results are not in very good agreement with the simulation. This result can be then explained by the major role of interfacial state between Duralumin and tungsten carbide.

  • Periodical Homogenisation technique and experimental comparison using acoustic microscopy and resonant ultrasonic spectroscopy
    Ultrasonics, 2006
    Co-Authors: D. Laux, J.-y. Ferrandis, C. Lévêque, J.-m. Gatt
    Abstract:

    The macroscopic elastic properties of two composites (Duralumin/air and Duralumin/tungsten carbide (WC)) have been calculated using periodical Homogenisation Methods and the elastic properties of each phase (measured by high frequency acoustic microscopy). In order to check the validity of such an approach, acoustical resonant spectroscopy has also been applied. Thanks to the comparison between the resonant frequencies predicted and measured, two major conclusions have been obtained: the Homogenisation Method is very accurate for the composite Duralumin/air, but not for the Duralumin/WC sample: the experimental results are not in very good agreement with the simulation. This result can be then explained by the major role of interfacial state between Duralumin and tungsten carbide

Raffaella Rizzoni - One of the best experts on this subject based on the ideXlab platform.

  • on modelling brick mortar interface via a st venant kirchhoff orthotropic soft interface part i theory
    International Journal of Masonry Research and Innovation, 2016
    Co-Authors: Maria Letizia Raffa, Frederic Lebon, Raffaella Rizzoni
    Abstract:

    In this paper, a nonlinear-imperfect interface model is proposed in order to model brick/mortar-interface behavior in small masonry assemblies. The proposed model, formulated according a micromechanical strategy, derives from a consolidated approach coupling arguments of asymptotic analysis and Homogenisation Method. The adopted asymptotic technique is extended to the finite strain theory. The Homogenisation strategy, under the non-interacting approximation, is extended to microcracked-orthotropic-hyperelastic materials. Simple numerical simulations, developed within the framework of finite element Method, highlight the model soundness and its applicability in finite-strain problems.

  • On modelling brick/mortar interface via a St. Venant-Kirchhoff orthotropic soft interface. Part I: theory
    International Journal of Masonry Research and Innovation, 2016
    Co-Authors: Maria Letizia Raffa, Frederic Lebon, Raffaella Rizzoni
    Abstract:

    In this paper, a nonlinear-imperfect interface model is proposed in order to model brick/mortar-interface behavior in small masonry assemblies. The proposed model, formulated according a micromechanical strategy, derives from a consolidated approach coupling arguments of asymptotic analysis and Homogenisation Method. The adopted asymptotic technique is extended to the finite strain theory. The Homogenisation strategy, under the non-interacting approximation, is extended to microcracked-orthotropic-hyperelastic materials. Simple numerical simulations, developed within the framework of finite element Method, highlight the model soundness and its applicability in finite-strain problems.

Heh Han Meijer - One of the best experts on this subject based on the ideXlab platform.

  • Homogenisation of structured elastoviscoplastic solids at finite strains
    Mechanics of Materials, 2001
    Co-Authors: Van Der O Olaf Sluis, Pjg Piet Schreurs, Heh Han Meijer
    Abstract:

    Abstract Studying the relation between microstructural phenomena and the macroscopic behaviour will provide a way to design the microstructure of a material such that specific requirements on the resulting macroscopic mechanical behaviour can be fulfilled. One way to obtain a quantitative relation between the separate scales is to use Homogenisation Methods. A numerical Homogenisation Method has been developed to model the mechanical behaviour of heterogeneous elastoviscoplastic solids at finite strains. The thus obtained constitutive equation enables the modelling of complex macrostructures, while taking into account the influence of the microstructure. The Method has been validated by comparing results of homogenised simulations with reference solutions. For this purpose, a specimen with a periodic microstructure and an irregular microstructure has been considered.The continuous matrix material is assumed to be polycarbonate, whereas the heterogeneities are taken to be rubber particles and voids.

  • Homogenisation of heterogeneous viscoplastic materials
    1999
    Co-Authors: Van Der O Olaf Sluis, Pjg Piet Schreurs, Heh Han Meijer
    Abstract:

    Heterogeneous materials have been used extensively in the past few decades, since their mechanical properties, such as strength, stiffness and toughness are being improved continuously. Experimental work has clearly demonstrated the significant influence of the micromechanical phenomena on the resulting overall macroscopic deformation behaviour of the material. Nevertheless, more fundamental studies are needed for a better understanding of the deformation behaviour of these materials. Relations between the microstructural phenomena and the macroscopic deformation behaviour are indispensable when predicting macroscopic properties from the microstructure. Homogenisation provides a way in determining this relation. The Homogenisation process aims at replacing the heterogeneous material with an equivalent continuum model, for which a closed-form constitutive equation is derived. Assuming statistical homogeneity of the heterogeneous material, it is possible to identify an element whose mechanical behaviour is representative for the heterogeneous material as a whole, a so-called representative volume element (RVE). In the Homogenisation Method proposed in this paper, finite element calculations are performed on the microstructural level, and therefore no simplifying assumptions concerning the microstructure of the material are required. First, the proposed Homogenisation strategy is validated numerically. Here, the obtained homogenised values are used to simulate various loading histories on a perforated plate. The obtained global behaviour is confronted with direct finite element calculations on the complete heterogeneous structure. From this, we have concluded that the proposed Homogenisation Method results in a fairly accurate and time-efficient prediction of the mechanical behaviour of the heterogeneous structure. Experiments have been used as well to evaluate the Method. Thermoplastic sheets with an arbitrary distributed hole pattern, are subjected to tensile and shear loadings. First, the material is characterised by standard techniques. Then, the RVE is defined, after which an effective parameter set for this RVE is obtained. This parameter set is then used to model the mechanical behaviour of the experimentally tested perforated plate.