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  • 1. Alkmim, M. H.
    et al.
    Cuenca, J.
    De Ryck, L.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Model-based acoustic characterisation of muffler components and extrapolation to inhomogeneous thermal conditions2018Inngår i: Proceedings of ISMA 2018 - International Conference on Noise and Vibration Engineering and USD 2018 - International Conference on Uncertainty in Structural Dynamics, KU Leuven - Departement Werktuigkunde , 2018, s. 3009-3020Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A methodology for evaluating the acoustic behaviour of two-port inhomogeneous media in experimentally unavailable thermal conditions is proposed. The method consists of an inverse estimation of the geometrical and material properties of the object at room temperature followed by a forced thermal input. The properties of interest for the inverse estimation are the spatially-varying cross-section and/or bulk properties. The underlying model relies on a transfer matrix approach, allowing for a representation of spatially inhomogeneous objects as piece-wise equivalent homogeneous fluids, while ensuring continuity conditions between successive elements. A model of non-stationary thermal conduction is used as a first approximation, where an integral formulation accounts for the cumulative effect of multiple homogeneous elements. In order to evaluate the validity of the extrapolation, a validation against a fully numerical simulation is presented in two cases, namely a simple expansion chamber and a complex muffler. 

  • 2.
    Alkmim, Mansour
    et al.
    Siemens Industry Software.
    Cuenca, Jacques
    Siemens Industry Software, Leuven Belgium.
    de Ryck, Laurent
    Siemens Industry Software, Leuven Belgium.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet. Centre for ECO2 Vehicle Design.
    Model-based acoustic characterisation of muffler components and extrapolation to inhomogeneous thermal conditions2018Konferansepaper (Fagfellevurdert)
  • 3.
    Bouchouireb, Hamza
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    O'Reilly, Ciarán J.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Schöggl, Josef-Peter
    University of Graz, Institute of Systems Sciences Innovation & Sustainability Research, Austria.
    Baumgartner, Rupert J.
    University of Graz, Institute of Systems Sciences Innovation & Sustainability Research, Austria.
    Potting, José
    KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design. KTH, Skolan för arkitektur och samhällsbyggnad (ABE).
    The inclusion of vehicle shape and aerodynamic drag estimations within the life cycle energy optimisation methodology2019Inngår i: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 84, s. 902-907Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The present work describes a widening of the scope of the Life Cycle Energy Optimisation (LCEO) methodology with the addition of shape-related design variables. They describe the curvature of a vehicle which impacts its aerodynamic drag and therewith its operational energy demand. Aerodynamic drag is taken into account through the estimation of the drag coefficient of the vehicle body shape using computational fluid dynamics simulations. Subsequently, the aforementioned coefficient is used to calculate the operational energy demand associated with the vehicle. The methodology is applied to the design of the roof of a simplified 2D vehicle model which is both mechanically and geometrically constrained. The roof is modelled as a sandwich structure with its design variables consisting of the material compositions of the different layers, their thicknesses as well as the shape variables. The efficacy of the LCEO methodology is displayed through its ability to deal with the arising functional conflicts while simultaneously leveraging the design benefits of the underlying functional alignments. On average, the optimisation process resulted in 2.5 times lighter and 4.5 times less life cycle energy-intensive free shape designs. This redesign process has also underlined the necessity of defining an allocation strategy for the energy necessary to overcome drag within the context of vehicle sub-system redesign.

  • 4.
    Bouchouireb, Hamza
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    O'Reilly, Ciarán J.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Schöggl, Josef-Peter
    KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design. University of Graz, Institute of Systems Sciences Innovation & Sustainability Research, Austria.
    Baumgartner, Rupert J.
    University of Graz, Institute of Systems Sciences Innovation & Sustainability Research, Austria.
    Potting, José
    KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Towards holistic energy-efficient vehicle product system design: The case for a penalized continuous end-of-life model in the life cycle energy optimisation methodology2019Inngår i: 22nd International Conference on Engineering Design, ICED19, Cambridge University Press, 2019, Vol. 1, s. 2901-2910Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The Life Cycle Energy Optimisation (LCEO) methodology aims at finding a design solution that uses a minimum amount of cumulative energy demand over the different phases of the vehicle's life cycle, while complying with a set of functional constraints. This effectively balances trade-offs, and therewith avoids sub-optimal shifting between the energy demand for the cradle-to-production of materials, operation of the vehicle, and end-of-life phases. The present work describes the extension of the LCEO methodology to perform holistic product system optimisation. The constrained design of an automotive component and the design of a subset of the processes which are applied to it during its life cycle are simultaneously optimised to achieve a minimal product system life cycle energy. A subset of the processes of the end-of-life phase of a vehicle’s roof are modelled through a continuous formulation. The roof is modelled as a sandwich structure with its design variables being the material compositions and the thicknesses of the different layers. The results show the applicability of the LCEO methodology to product system design and the use of penalisation to ensure solution feasibility.

  • 5.
    Cameron, Christopher J.
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Nordgren, Eleonora Lind
    KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Wennhage, Per
    KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    On the balancing of structural and acoustic performance of a sandwich panel based on topology, property, and size optimization2014Inngår i: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 333, nr 13, s. 2677-2698Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Balancing structural and acoustic performance of a multi-layered sandwich panel is a formidable undertaking. Frequently the gains achieved in terms of reduced weight, still meeting the structural design requirements, are lost by the changes necessary to regain acceptable acoustic performance. To alleviate this, a design method for a multifunctional load bearing vehicle body panel is proposed which attempts to achieve a balance between structural and acoustic performance. The approach is based on numerical modelling of the structural and acoustic behaviour in a combined topology, size, and property optimization in order to achieve a three dimensional optimal distribution of structural and acoustic foam materials within the bounding surfaces of a sandwich panel. In particular the effects of the coupling between one of the bounding surface face sheets and acoustic foam are examined for its impact on both the structural and acoustic overall performance of the panel. The results suggest a potential in introducing an air gap between the acoustic foam parts and one of the face sheets, provided that the structural design constraints are met without prejudicing the layout of the different foam types.

  • 6.
    Cameron, Christopher John
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Lind, Eleonora
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Wennhage, Per
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Material Property Steered Optimization of a Multifunctional Body Panel to Structural and Acoustic Constraints2009Inngår i: Proceedings of the 17th International Conference on Composite Materials, 2009Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    A conventional automobile roof, including structural and interior trim components, is replaced with a multi-layer, multi-functional sandwich construction. A weight optimizationis performed to tailor the material properties of the composite face sheets and multiple foam layers to meet structural constraints and acoustic requirements.

  • 7.
    Cameron, Christopher John
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Lind, Eleonora
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Wennhage, Per
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Proposal of a Methodology for Multidisciplinary Design of Multifunctional Vehicle Structures including an Acoustic Sensitivity Study2009Inngår i: International Journal of Vehicle Structures & Systems, ISSN 0975-3060, Vol. 1, nr 1-3, s. 3-15Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, a design methodology is proposed, wherein tools and knowledge from the areas of structural design, numerical optimization, and noise, vibration and harshness (NVH) engineering are combined into a single toolbox for vehicle design. The methodology attempts to address the topic of sustainable development from both economic and environmental perspectives within the vehicle industry. A brief review of the topics of NVH and numerical optimization is given for the purposes of disseminating knowledge. Finite element codes for predicting structural and acoustic response are implemented within the iterative design methodology, which is explained for generic problems. Specific focus is placed on the need for understanding functional requirements of the entire system rather than its components. The methodology is implemented in an automotive case study. The results in terms of design solution and development framework are evaluated and discussed. As part of this evaluation, and integral to the design process, an acoustic sensitivity analysis of the final solution is performed and the results are presented.

     

     

  • 8.
    Cameron, Christopher John
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Lind Nordgren, Eleonora
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Wennhage, Per
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    A Design Method using Toplogy, Property, and Size Optimization to Balance Structural and Acoustic Performance of Sandwich Panels for Vehicle ApplicationsManuskript (preprint) (Annet vitenskapelig)
  • 9.
    Cameron, Christopher John
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Lind Nordgren, Eleonora
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Wennhage, Per
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Material Property Steered Structural and Acoustic Optimization of a Multifunctional Vehcile Body PanelManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Conventional vehicle passenger compartments often achieve functional requirements using a complex assembly of components. As each component is optimized for a single task, the assembly as a whole is often suboptimal in achieving the system performance requirements. In this paper, a novel iterative design approach based on using a multi-layered load bearing sandwich panel with integrated acoustic capabilitiesis developed focusing on material properties and their effecton the systems behavior. The proposed panel is meant to fulfilmultiple system functionalities simultaneously, thus simplifying the assembly and reducing mass. Open cell acoustic foams are used to achieve acoustic performance, and the effect of altering the stacking sequence as well as introducing an air gap within the acoustic treatment is studied in detail to determine effects on the acoustic and structural performance of the panel as a whole.

  • 10.
    Cameron, Christopher John
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Wennhage, Per
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Prediction of NVH behaviour of trimmed body components in the frequency range 100-500 Hz2010Inngår i: Applied Acoustics, ISSN 0003-682x, Vol. 71, nr 8, s. 708-721Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The work within this paper focuses on the application and validation of numerical methods for predicting the acoustic and structural NVH behaviour of trimmed body components in an automotive context. In particular, the level of modelling refinement and accuracy necessary to establish a reliable finite element analysis model for comparative purposes in the development of alternative designs is investigated. Specifically, the roof structure of a passenger car was investigated from various performance aspects, using both structural and acoustic excitation. The roof was initially tested in situ, with and without interior lining, to provide a reference for subsequent component tests. It was then detached from the car, mounted in a stiff frame and tested in a transmission window using both acoustic and structural excitation. A finite element model of the detached component was developed using shell and solid elements for the structure and solid elements for the interior lining. Predictions were carried out to evaluate the STL as well as the vibrational frequency response due to a force applied to the structure. Special attention was given to the modelling of the headliner as well as the air gap separating the headliner from the outer sheet metal. A sensitivity study of various headliner properties was performed in addition to a comparison between solutions calculated using standard Nastran elements and augmented poro-elastic elements via the software package CDH/EXEL. The main objective of the current work has been to establish a datum reference for alternative designs. From this aspect, the validation of the numerical modelling methodology, in particular the level of detail and accuracy used, was a crucial step. It was found that the predictions agreed very well with the measured data. As an additional, very interesting result, it was also found that the in situ testing correlated well with the transmission suite testing.

  • 11.
    Cameron, Christopher John
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Wennhage, Per
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Rahmqvist, Sven
    Saab Automobile AB.
    Structural: acoustic Design of a Multi-functional Sandwich Body Panel for Automotive Applications2008Inngår i: Proceedingsof the 8th International Conference on Sandwich Structures / [ed] A. J. M. Ferreira, 2008, s. 896-907Konferansepaper (Annet vitenskapelig)
  • 12.
    Cameron, Christopher John
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Wennhage, Per
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Rahmqvist, Sven
    Saab Automobile AB, Technical Integration Engineer - Body Structure and Closures, Noise & Vibration Center, Sweden.
    Structural-acoustic Design of a Multi-functional Sandwich Panel in an Automotive Context2010Inngår i: Journal of Sandwich Structures and Materials, ISSN 1099-6362, E-ISSN 1530-7972, Vol. 12, nr 6, s. 684-708Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This article deals with the design and weight optimization of a multi-functional vehicle body panel in an automotive context. An existing vehicle design has provided functional design requirements regarding static, dynamic, and acoustic behavior of the components of a car roof. A novel, multifunctional panel is proposed which integrates the component requirements present in a traditional roof system within a single module. The acoustic properties of two configurations of the novel panel are examined using numerical methods including advanced poro-elastic modeling tools compatible with Nastran, and compared with numerical results of a finite element model of the existing construction.

  • 13.
    Cameron, Christopher
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Lind, Eleonora
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Wennhage, Per
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Balancing structural and acoustic performance of sandwich panels for vehicle applications with topology, property, and size optimization2010Inngår i: 7th Asian-Australasian Conference on Composite Materials 2010, ACCM 2010, ACCM-7 Organizing Committee , 2010, Vol. 2, s. 835-838Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Within this paper, a process for the design of a multifunctional sandwich body panel for vehicle applications is proposed. The method, presented with a case study, attempts to achieve a balance between structural and acoustic performance using numerical tools for topology optimization and combined size and property optimization. The goal of the work is to achieve an optimal distribution of traditional sandwich foam material and light weight acoustic foam within the core of the panel. The significance of the coupling between the panels inner face sheet and the acoustic foam is examined and proves to be a critical parameter in the design. An adaptation to existing topology optimization schemes is proposed to deal with the presence or absence of such a coupling. The results show promise in simplifying construction, reducing weight, and streamlining the assembly process.

  • 14.
    Cameron, Christopher
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Wennhage, Per
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Multi-Scale Structural-Acoustic Optimization of a Multi-Functional Vehicle Body Panel2009Konferansepaper (Annet vitenskapelig)
  • 15.
    Cuenca, Jacques
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Inverse estimation of the elastic and anelastic properties of the porous frame of anisotropic open-cell foams2011Konferansepaper (Annet vitenskapelig)
  • 16.
    Cuenca, Jacques
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Inverse estimation of the elastic and anelastic properties of the porous frame of anisotropic open-cell foams2012Inngår i: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 132, nr 2, s. 621-629Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents a method for simultaneously identifying both the elastic and anelastic properties of the porous frame of anisotropic open-cell foams. The approach is based on an inverse estimation procedure of the complex stiffness matrix of the frame by performing a model fit of a set of transfer functions of a sample of material subjected to compression excitation in vacuo. The material elastic properties are assumed to have orthotropic symmetry and the anelastic properties are described using a fractional-derivative model within the framework of an augmented Hooke's law. The inverse estimation problem is formulated as a numerical optimization procedure and solved using the globally convergent method of moving asymptotes. To show the feasibility of the approach a numerically generated target material is used here as a benchmark. It is shown that the method provides the full frequency-dependent orthotropic complex stiffness matrix within a reasonable degree of accuracy.

  • 17.
    Cuenca, Jacques
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. Siemens Industry Software, Interleuvenlaan 68, Leuven, B-3001, Belgium.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    De Ryck, L.
    Lähivaara, T.
    Inverse parameter estimation in resonant, coupled fluid-structure interaction problems2018Inngår i: Proceedings of ISMA 2018 - International Conference on Noise and Vibration Engineering and USD 2018 - International Conference on Uncertainty in Structural Dynamics, KU Leuven - Departement Werktuigkunde , 2018, s. 2155-2169Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This work discusses the estimation of model parameters in resonant coupled systems over a wide frequency range. Such problems are known to be subjected to local minima, which represent a major obstacle in the field of parameter identification. This work evaluates various approaches to finding the global minimum, i.e. the true model parameters. The L2 norm between a target and a model frequency response function is used as the objective function. The estimation is performed through deterministic and statistical inversion frameworks, using both full-spectrum and step-wise approaches. The occurrence and the background of local minima are discussed and the performance of the different solution methods is evaluated. In particular, the correlation between different model parameters is analysed and observed to control the path towards the solution. Two illustrative examples are proposed, including the estimation of geometrical and material properties of an expansion chamber coupled to a limp porous material.

  • 18.
    Cuenca, Jacques
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. Siemens Industry Software, Leuven Belgium.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. Centre for ECO2 Vehicle Design.
    de Ryck, Laurent
    Siemens Industry Software, Leuven Belgium.
    Lähivaara, Timo
    University of Eastern Finland.
    Inverse parameter estimation in resonant, coupled fluidstructure interaction problems2018Konferansepaper (Fagfellevurdert)
  • 19.
    Cuenca, Jacques
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Van der Kelen, Christophe
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik. KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet. KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    A general methodology for inverse estimation of the elastic and anelastic properties of anisotropic open-cell porous materials-with application to a melamine foam2014Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 115, nr 8, s. 084904-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper proposes an inverse estimation method for the characterisation of the elastic and anelastic properties of the frame of anisotropic open-cell foams used for sound absorption. A model of viscoelasticity based on a fractional differential constitutive equation is used, leading to an augmented Hooke's law in the frequency domain, where the elastic and anelastic phenomena appear as distinctive terms in the stiffness matrix. The parameters of the model are nine orthotropic elastic moduli, three angles of orientation of the material principal directions and three parameters governing the anelastic frequency dependence. The inverse estimation consists in numerically fitting the model on a set of transfer functions extracted from a sample of material. The setup uses a seismic-mass measurement repeated in the three directions of space and is placed in a vacuum chamber in order to remove the air from the pores of the sample. The method allows to reconstruct the full frequency-dependent complex stiffness matrix of the frame of an anisotropic open-cell foam and in particular it provides the frequency of maximum energy dissipation by viscoelastic effects. The characterisation of a melamine foam sample is performed and the relation between the fractional-derivative model and other types of parameterisations of the augmented Hooke's law is discussed.

  • 20.
    Cuenca, Jacques
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik. Siemens Industrial Software, Leuven Belgium.
    Van der Kelen, Christophe
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik. Centre for ECO2 Vehicle Design.
    Inverse estimation of the elastic and anelastic properties of anisotropic foams: study of the static/dynamic separation.2015Inngår i: EURONOISE 2015, 2015Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper investigates the modelling and characterisation of the porous frame of anisotropic open-cell foams. The main objective is to nd a suitable model for describing the elastic and anelasticproperties of the material by making as few assumptions as possible. The proposed model is basedon a fractional di erential equation, taking into account the deformation memory of the materialin a versatile and compact manner. In the frequency domain, this results in an augmented Hooke'slaw, where the sti ness matrix of the porous frame consists of a superposition of a fully-relaxed,frequency-independent elastic part, and a dynamic, frequency-dependent anelastic part. In order toestimate the properties of the material and to determine if the elastic and anelastic parts sharethe same material symmetry, two separate experiments are performed. A static photometry setup isdesigned, where a cubic sample of material is compressed along each of the three directions of spacewhile the deformation is recorded on the four exposed faces. Furthermore, a dynamic measurementof a set of transfer functions between each pair of opposed faces of the sample is performed. Thecharacterisation methodology consists of an inverse estimation of the parameters of the model. Thisis acheved by replicating each experiment as a nite element simulation and tting the model byusing an optimisation algorithm. The static and dynamic observations serve as a basis for discussingthe independence of the elastic and anelastic properties of the material.

  • 21.
    Cuenca, Jacques
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik. Siemens Industrial Software Leuven Belgium.
    Van der Kelen, Christophe
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Inverse estimation of the elastic and anelastic properties of anisotropic open-cell foams2014Konferansepaper (Annet vitenskapelig)
  • 22.
    Dazel, O.
    et al.
    LAUM, Uni du Maine, Le Mans France.
    Brouard, B.
    LAUM, Uni du Maine, Le Mans France.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    An efficient solver for finite-element poroelastic problems2012Inngår i: Proceedings - European Conference on Noise Control, 2012, s. 851-853Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Structural-acoustic finite element models including 3D modelling of poroelastic media modelled with the Biot theory are generally computationally costly. While being the most commonly used predictive tool in the context of noise reduction applications, efficient solution strategies are required. In this work, an original modal reduction technique, involving real-valued decoupled modes computed from a classical eigenvalue solver is proposed to reduce the size of the problem associated to the porous media. The idea of this technique is to enhance the modal basis with static correction calculated analytically which account for the response of non-preserved modes.

  • 23.
    Dazel, Olivier
    et al.
    Université du Maine, Le Mans France.
    Brouard, B.
    Université du Maine, Le Mans France.
    Groby, J. -P
    Université du Maine, Le Mans France.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    A normal modes technique to reduce the order of poroelastic models: application to 2D and coupled 3D models2013Inngår i: International Journal for Numerical Methods in Engineering, ISSN 0029-5981, E-ISSN 1097-0207, Vol. 96, nr 2, s. 110-128Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A reduced-order model for structures involving poroelastic materials is proposed in this paper. The approach is based on a separation of the solid and fluid phases of the porous material into separate substructures. For each individual substructure, a decoupled normal mode basis is considered, from which a set of vectors for the decomposition is selected. The preserved modes are completed by an additional family to correct for the influence of the static response of the non-preserved. It is shown that the only neglected phenomenons in the model are the inertia of the non-preserved modes and part of their intercoupling. The following three features render the proposed scheme computationally attractive: (i) real valued matrices are involved in the transformations; (ii) the assembly of complex, frequency dependent matrices is only performed at the stage of solving for a particular frequency; and (iii) the number of normal modes required are selected using a novel method.The computational efficacy is demonstrated, on a simple but realistic 3D case, through numerical results obtained using a reduced number of DOFs, showing a significant reduction of computational cost compared with traditional methods.

  • 24.
    Dazel, Olivier
    et al.
    U de Maine.
    Brouard, Bruno
    U de Maine.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    An efficient solver for finite-element poroelastic problems2011Konferansepaper (Annet vitenskapelig)
  • 25.
    dell'Isola, Francesco
    et al.
    Univ Aquila, Int Res Ctr M&MoCS, Laquila, Italy.;Univ Aquila, Dipartimento Ingn Civile Edile Architettura & Amb, Laquila, Italy.;Natl Res Lobachevsky State Univ Nizhni Novgorod, Res Inst Mech, Nizhnii Novgorod, Russia.;King Abdulaziz Univ, NAAM Res Grp, Dept Math, Jeddah 21589, Saudi Arabia..
    Manzari, Luca
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Hayat, Tasawar
    King Abdulaziz Univ, NAAM Res Grp, Dept Math, Jeddah 21589, Saudi Arabia..
    Advances in pantographic structures: design, manufacturing, models, experiments and image analyses2019Inngår i: Continuum Mechanics and Thermodynamics, ISSN 0935-1175, E-ISSN 1432-0959, Vol. 31, nr 4, s. 1231-1282Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the last decade, the exotic properties of pantographic metamaterials have been investigated and different mathematical models (both discrete or continuous) have been introduced. In a previous publication, a large part of the already existing literature about pantographic metamaterials has been presented. In this paper, we give some details about the next generation of research in this field. We present an organic scheme of the whole process of design, fabrication, experiments, models and image analyses.

  • 26.
    Dovstam, Krister
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Generic FE modelling of linear interface damping in vibrating structures2008Inngår i: PROCEEDINGS OF ISMA 2008: INTERNATIONAL CONFERENCE ON NOISE AND VIBRATION ENGINEERING, VOLS. 1-8, 2008, s. 843-Konferansepaper (Fagfellevurdert)
  • 27.
    Dovstam, Krister
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Is damping additive?: On the accumulated effect of interface damping and material damping2010Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Traditionally the structural loss factor of a vibrating structure at resonance is defined by the half power bandwidth which then incorporates all mechanisms, e. g. material damping, interface damping, added viscoelastic damping, acoustic damping and damping in joints, contributing to the total damping. Damping measures based on vibration response data and vibration energy dissipated locally at interfaces and in material volumes may be computed in post processing finite element computations. Appropriately defined measures may then localize the damping to interfaces and material volumes where the dissipation actually occurs. It is also possible to separate and quantify the damping contributions from different damping sources. The interaction and combined effect of mixed material and interface damping is studied for a simple, three dimensional, build-up structure containing overlapping contact interfaces and internal regions with material damping. Results are presented based on damping measures which separate damping contributions from different contact interfaces and internal material volumes. By comparison of the total structural damping with partial contributions, from the specific damping sources occurring in each case, the combined, accumulated, effect of the different sources is investigated. The question whether different kinds of damping is additive or not is finally addressed.

  • 28.
    Dovstam, Krister
    et al.
    Dovstam Innovat.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Mode based prediction of vibrations in highly damped structures2006Inngår i: Proceedings of ISMA2006: International Conference on Noise and Vibration Engineering, 2006, s. 1029-1038Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Traditionally, mode based techniques are used for prediction of sound and vibrations. This is motivated by the possibility of using reduced modal models instead of very detailed FE models. For highly damped, composite structures the effect of reduced model size on the accuracy of predicted sound and vibration levels is often not known. Problems connected with application of modal methods towards highly damped materials, systems and multilayer treatments using conventional modal vibration theory have recently been highlighted by the authors. In the present paper a simple, damped Oberst beam example is presented, not hitherto satisfactorily treated by modal techniques. It is pointed out that the contact forces at internal interfaces between different materials have to be treated in order for a modal solution to be found. It is also shown that non-physical tractions at free unloaded boundary surfaces have to be eliminated.

  • 29.
    Dovstam, Krister
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Gartmeier, Otto
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    On linear modeling of interface damping in vibrating structures2012Inngår i: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 331, nr 19, s. 4299-4312Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dissipation of mechanical vibration energy at contact interfaces in a structure, commonly referred to as interface damping, is an important source of vibration damping in built-up structures and its modeling is the focus of the present study. The approach taken uses interface forces which are linearly dependent on the relative vibration displacements at the contact interfaces. The main objective is to demonstrate a straightforward technique for simulation of interface damping in built-up structures using FE modeling and simple, distributed, damping forces localized to interfaces where the damping occurs. As an illustration of the resulting damping the dissipated power is used for evaluation purposes. This is calculated from surface integrals over the contact interfaces and allows for explicit assessment of the effect of simulated interface forces for different cases and frequencies. The resulting loss factor at resonance is explicitly evaluated and, using linear simulations, it is demonstrated that high damping levels may arise even though the displacement differences between contacting surfaces at damped interfaces may be very small.

  • 30.
    Dovstam, Krister
    et al.
    Dovstam Innovations.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Semeniuk, Bradley
    Rieter Automotive Managment AG, Switzerland.
    Mode based prediction of vibrations in complex automotive structures, a review of shortcomings2005Konferansepaper (Fagfellevurdert)
  • 31.
    Dowling, Luke
    et al.
    Trinity College Dublin.
    Mao, Huina
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Flanagan, Lara
    Trinity College Dublin.
    Kennedy, John
    Trinity College Dublin.
    Rice, H J
    Trinity College Dublin.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Cuenca, Jacques
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. Siemens Industry Software, Leuven Belgium.
    A combined design-manufacturing-testing investigation of micro- to macro-scale tailoring of open poroelastic materials based on perturbed kelvin cell micro-geometries2018Inngår i: Proceedings of ISMA 2018 - International Conference on Noise and Vibration Engineering and USD 2018 - International Conference on Uncertainty in Structural Dynamics, 1177 , 2018, s. 1163-1177Konferansepaper (Fagfellevurdert)
  • 32. Ericsson, A.
    et al.
    Rumpler, Romain
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Sjöberg, D.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Wellander, N.
    Johansson, J.
    A combined electromagnetic and acoustic analysis of a triaxial carbon fiber weave for reflector antenna applications2016Inngår i: Aerospace Science and Technology, ISSN 1270-9638, E-ISSN 1626-3219, Vol. 58, s. 401-417Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fiber composites are widely used for space applications such as antennas, solar panels and spacecraft support structures. This paper presents a combined electromagnetic and acoustic analysis of a triaxial carbon fiber weave structure, designed for ultra lightweight reflector antennas in satellite communication systems. The electromagnetic and acoustic performance of the structure are analyzed over a wide range of parametric studies, both at a microscopic and mesoscopic length scale. The electromagnetic study indicates that the main parameter governing the electromagnetic reflection performance of the weave is the electric conductivity of the carbon fibers, given that the weave structure is significantly smaller than the wavelength of the incident signals. The acoustic study identifies a critical threshold in the mesoscale geometry in order to avoid a critically high resistive behavior of the weave structure, driven by viscous effects. Design guidelines are drawn from these analyses in order to achieve a trade-off between the electromagnetic reflection properties and the resistance to acoustic loading of such composite materials. These combined analyses allow to deepen the understanding from both an electromagnetic and acoustic perspective in order to open for some new design possibilities.

  • 33.
    Färm, Anna
    et al.
    Centre for ECO Vehicle Design, Scania CV, Södertälje, Sweden.
    Boij, Susann
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strömningsakustik.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Glav, Ragnar
    Scania CV, Södertälje, Sweden.
    On internal mean flow in porous absorbers and its effect on attenuation properties2013Inngår i: Proceedings of Meetings on Acoustics: Volume 19, 2013, Acoustical Society of America (ASA), 2013, Vol. 19, s. 1-6Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    In vehicle applications, absorbing materials are often used to attenuate sound. In, for example, exhaust systems and on noise encapsulations, the absorber is exposed to flow. This creates a boundary layer above the absorber, which affects the impedance of the surface, and hence alters the absorption properties. In addition to this effect, the flow itself may enter the absorbent material due to high pressure and forced flow paths. An investigation of the effects that internal flow in the absorber imposes on the acoustic properties is presented. One way to describe the effect is by a change in flow resistivity. The effect is investigated for typical absorbers used in noise encapsulations for trucks. The Transfer Matrix Method is applied to calculate the resulting absorption coefficient for an absorber with changed flow resistivity due to internal flow. The possibility to model the changed properties of the absorber with internal mean flow by means of Biot theory is also explored, together with a discussion on suitable experimental methods to verify and further investigate the effects.

  • 34.
    Gaborit, Mathieu
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet. Le Mans Univ, Lab Acoust, CNRS, UMR 6613,Univ Mans, F-72000 Le Mans, France.
    Dazel, Olivier
    Le Mans Univ, Lab Acoust, CNRS, UMR 6613,Univ Mans, F-72000 Le Mans, France..
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    A simplified model for thin acoustic screens2018Inngår i: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 144, nr 1, s. EL76-EL81Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A generalization of the commonly used pressure jump modeling of thin porous layers is proposed. The starting point is a transfer matrix model of the layer derived using matrix exponentials. First order expansions of the propagating terms lead to a linear approximation of the associated phenomena and the resulting matrix is further simplified based on physical assumptions. As a consequence, the equivalent fluid parameters used in the model may be reduced to simpler expressions and the transfer matrix rendered sparser. The proposed model is validated for different backing conditions, from normal to grazing incidence and for a wide range of thin films. In the paper, the physical hypotheses are discussed, together with the origin of the field jumps.

  • 35.
    Gaborit, Mathieu
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Dazel, Olivier
    LAUM UMR CNRS 6613, Le Mans Université, Le Mans, France.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Erratum: A simplified model for thin acoustic screens [J. Acoust. Soc. Am. 144(1), EL76–EL81 (2018)]2019Inngår i: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 146, nr 2, s. 1382-1383Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The present erratum reports an error impacting the figures of a contribution published in 2018 about a simplified model for thin acoustic screens in a transfer matrix context [Gaborit, Dazel, and Göransson (2018). J. Acoust. Soc. Am. 144(1), EL76–EL81]. A mistake in the implementation of the rigid termination condition for the systems under study is identified and a correct version is proposed along with the corrected figures. It is shown that this error does not impact the conclusions of the original contribution and that the model proposed therein keeps its advantages as the approximation error remains very similar to the previously reported values.

  • 36.
    Gaborit, Mathieu
    et al.
    University of Le Mans.
    Dazel, Olivier
    Université du Maine, Le Mans France.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet. Centre for ECO2 Vehicle Design.
    Gabard, Gwenael
    University of Le Mans.
    Coupling of finite element and plane waves discontinuous Galerkin methods for time-harmonic problems2018Inngår i: International Journal for Numerical Methods in Engineering, ISSN 0029-5981, E-ISSN 1097-0207, Vol. 116, nr 7, s. 487-503Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A coupling approach is presented to combine a wave-based method to the standard finite element method. This coupling methodology is presented here for the Helmholtz equation but it can be applied to a wide range of wave propagation problems. While wave-based methods can significantly reduce the computational cost, especially at high frequencies, their efficiency is hampered by the need to use small elements to resolve complex geometric features. This can be alleviated by using a standard finite element model close to the surfaces to model geometric details and create large, simply-shaped areas to model with a wave-based method. This strategy is formulated and validated in this paper for the wave-based discontinuous Galerkin method together with the standard finite element method. The coupling is formulated without using Lagrange multipliers and results demonstrate that the coupling is optimal in that the convergence rates of the individual methods are maintained.

  • 37.
    Gaborit, Mathieu
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Dazel, Olivier
    LAUM UMR CNRS 6613, Le Mans Université, Le Mans, France.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Gabard, Gwenaël
    LAUM UMR CNRS 6613, Le Mans Université, Le Mans, France.
    Coupling of Finite-Element and Plane Waves Discontinuous Galerkin methods for time-harmonic problems2018Inngår i: International Journal for Numerical Methods in Engineering, ISSN 0029-5981, E-ISSN 1097-0207, Vol. 116, nr 7, s. 487-503Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A coupling approach is presented to combine a wave‐based method to the standard finite element method. This coupling methodology is presented here for the Helmholtz equation but it can be applied to a wide range of wave propagation problems. While wave‐based methods can significantly reduce the computational cost, especially at high frequencies, their efficiency is hampered by the need to use small elements to resolve complex geometric features. This can be alleviated by using a standard finite element model close to the surfaces to model geometric details and create large, simply‐shaped areas to model with a wave‐based method. This strategy is formulated and validated in this paper for the wave‐based discontinuous Galerkin method together with the standard finite element method. The coupling is formulated without using Lagrange multipliers and results demonstrate that the coupling is optimal in that the convergence rates of the individual methods are maintained.

  • 38.
    Gaborit, Mathieu
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Dazel, Olivier
    LAUM UMR CNRS 6613, Le Mans Université, Le Mans, France.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Jaouen, Luc
    Matelys Research Lab.
    Response envelope generation for thin acoustic screens with uncertain parametersManuskript (preprint) (Annet vitenskapelig)
  • 39.
    Gaborit, Mathieu
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet. Université du Maine, Le Mans France.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik. KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design. Centre for ECO2 Vehicle Design.
    Dazel, Olivier
    Université du Maine, Le Mans France.
    Simplification of the transfer matrix model for acoustic screens2018Konferansepaper (Fagfellevurdert)
  • 40.
    Gaborit, Mathieu Maël
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet. Université du Maine, France.
    Schwan, L.
    Dazel, O.
    Groby, J. -P
    Weisser, T.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Coupling FEM, bloch waves and TMM in meta poroelastic laminates2018Inngår i: Acta Acoustica united with Acustica, ISSN 1610-1928, E-ISSN 1861-9959, Vol. 104, nr 2, s. 220-227Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The propagation of airborne plane waves in the presence of a meta poroelastic laminate, that is a poroelastic matrix coated with thin elastic layers at its facings and periodically-embedded with inclusions, is studied. Using the Finite Element Method (FEM) only would result in a drastic increase of the degrees of freedom due to the fine mesh required to account for the very thin coatings. Here, the approach relies on: The Bloch wave expansion of the fields in air; the modal Transfer Matrix Method to account for the coatings; and the coupling with the FEM model of the poroelastic matrix and the resonant inclusions. The model is developed for reflection and transmission problems and it can account for coatings with multiple layers. The procedure induces the addition of the Bloch coefficients in the FEM's linear system at a negligible additional computational cost. It is applied to the meta poroelastic laminates with poroelastic inclusions and rubber shell inclusions. The results are compared with those from the Multiple Scattering Theory and an excellent agreement between the methods is found. The approach offers a numerically-efficient way to account for coatings applied to meta poroelastic layers, and finds applications in industrial prototypes where coatings are widely used.

  • 41.
    Gao, K.
    et al.
    Eindhoven University of Technology, Mechanics of Materials, Department of Mechanical Engineering, The Netherlands.
    van Dommelen, J. A. W.
    Eindhoven University of Technology, Mechanics of Materials, Department of Mechanical Engineering, The Netherlands.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Geers, M. G. D.
    Eindhoven University of Technology, Mechanics of Materials, Department of Mechanical Engineering, The Netherlands.
    A homogenization approach for characterization of the fluid-solid coupling parameters in Biot's equations for acoustic poroelastic materials2015Inngår i: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 351, s. 251-267Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, a homogenization method is proposed to obtain the parameters of Biot's poroelastic theory from a multiscale perspective. It is assumed that the behavior of a macroscopic material point can be captured through the response of a microscopic Representative Volume Element (RVE) consisting of both a solid skeleton and a gaseous fluid. The macroscopic governing equations are assumed to be Biot's poroelastic equations and the RVE is governed by the conservation of linear momentum and the adopted linear constitutive laws under the isothermal condition. With boundary conditions relying on the macroscopic solid displacement and fluid pressure, the homogenized solid stress and fluid displacement are obtained based on energy consistency. This homogenization framework offers an approach to obtain Biot's parameters directly through the response of the RVE in the regime of Darcy's flow where the pressure gradient is dominating. A numerical experiment is performed in the form of a sound absorption test on a porous material with an idealized partially open microstructure that is described by Biot's equations where the parameters are obtained through the proposed homogenization approach. The result is evaluated by comparison with Direct Numerical Simulations (DNS), showing a superior performance of this approach compared to an alternative semiphenomenological model for estimating Biot's parameters of the studied porous material.

  • 42.
    Gao, K.
    et al.
    Eindhoven University of Technology, Mechanics of Materials, Department of Mechanical Engineering, The Netherlands.
    van Dommelen, J. A. W.
    Eindhoven University of Technology, Mechanics of Materials, Department of Mechanical Engineering, The Netherlands.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Geers, M. G. D.
    Eindhoven University of Technology, Mechanics of Materials, Department of Mechanical Engineering, The Netherlands.
    Computational homogenization of sound propagation in a deformable porous material including microscopic viscous-thermal effects2016Inngår i: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 365, s. 119-133Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Porous materials like acoustic foams can be used for acoustic shielding, which is important for high-tech systems and human comfort. In this paper, a homogenization model is proposed to investigate the relation between the microstructure and the resulting macroscopic acoustic properties. The macroscopic absorption ability is due to the microscopic viscous-thermal coupling between an elastic solid skeleton and a gaseous fluid in the associated Representative Volume Element (RVE). The macro-to-micro relation is realized through the boundary conditions of the microscopic RVE, which relies on the macroscopic solid deformation and fluid pressure gradient. By assuming that the variation of the macroscopic energy per unit volume equals the volume average of the variation of the microscopic energy, the macroscopic solid stress and fluid displacement can be calculated from the corresponding microscopic quantities. Making additional assumptions on this approach, Biot's poroelastic theory is recovered. A case study is performed through the simulations of sound absorption in three porous materials, one made from aluminum and two from different polyurethane foams. For simplicity, an idealized partially open cubic microstructure is adopted. The homogenization results are evaluated by comparison with Direct Numerical Simulations (DNS), revealing an adequate performance of the approach for the studied porous material. By comparing the results of different solid materials, it is found that the solid stiffness has a limited effect when resonance does not occur. Nevertheless, due to the absence of the microscopic fluctuation, Biot's model with the parameters obtained from the homogenization approach predicts a higher resonance frequency than the DNS, whereas a full homogenization modification improves the prediction.

  • 43.
    Gao, Kun
    et al.
    Eindhoven University of Technology, Mechanics of Materials, Department of Mechanical Engineering, The Netherlands.
    van Dommelen, J A W
    Eindhoven University of Technology, Department of Mechanical Engineering, The Netherlands.
    Geers, M G D
    Eindhoven University of Technology, Department of Mechanical Engineering, The Netherlands.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Microstructure-based numerical modelling of foams for acoustic shielding2014Inngår i: 21st International Congress on Sound and Vibration 2014, ICSV 2014, International Institute of Acoustics and Vibrations , 2014, s. 881-887Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, a numerical homogenization approach is proposed to obtain isotropic Biot's parameters based on the microstructure of an porous material. It is assumed that a macroscopic point can be represented by a microscopic Representative Volume Element (RVE) consisting of the solid and the fluid. The macroscopic properties are controlled by Biot's equations and the RVE is governed by linearized balance equations for momentum and linear constitutive laws. With suitable boundary conditions, the micro-macro relation is formulated based on consistency of energy. Then, Biot's parameters are calculated through the response of the RVE. By following this new homogenization approach, examples with simple microstructures are given and simulations of two sound absorption experiments are conducted by using Biot's equations. The results are compared with Direct Numerical Simulations and it shows a favourable performance of this new approach compared to the alternative Transfer Matrix Method.

  • 44.
    Gao, Kun
    et al.
    TU Eindhoven, Netherlands.
    van Dommelen, J A W
    TU Eindhoven, Netherlands.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Geers, M G D
    TU Eindhoven, Netherlands.
    Homogenization of sound propogation in a deformable porous material based on microscopic viscous-thermal effects.2014Konferansepaper (Fagfellevurdert)
  • 45.
    Gao, Kun
    et al.
    TU Eindhoven.
    Van Dommelen, J. A. W.
    TU Eindhoven.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Geers, M. G. D.
    TU Eindhoven.
    Microstructure-based numerical modeling of the solid-fluid coupling interaction in acoustic foams2013Inngår i: Poromechanics V - Proceedings of the 5th Biot Conference on Poromechanics, 2013, s. 2123-2130Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, based on a representative volume element (RVE) and Slattery’s averaging theorem, parameters of Biot’s poroelastic equations for homogenous isotropic porous materials are obtained. According to Slattery’s averaging theorem, the coupling terms, which describe the inertial effects and the viscous effects, are represented by an integral of the solid-fluid interaction force. This relation provides a new approach to obtain the parameters required in Biot’s equations through a direct numerical simulation of the RVE. An example of a 2D RVE is given and simulations of sound propagation in an impedance tube with a foam are conducted using Biot’s equations. It is shown that the numerical coupling mass obtained from this new approach behaves qualitatively the same as an associated phenomenological model.

  • 46.
    Guastavino, Remi
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Modeling and characterisation of the vibration dynamics modeling of anisotropic porous foam materials2006Inngår i: Proceedings of ISMA2006: International Conference on Noise and Vibration Engineering, Vols 1-8 / [ed] Sas, P; DeMunck, M, 2006, s. 1481-1487Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Accurate prediction of low to medium frequency surface vibration and sound radiation behavior of foam materials, requires improved means of estimating the dynamic elastic and damping properties of the foam. This need arises due to the geometric anisotropy in the foam cell microstructure, where the foam cells and struts are elongated in the rise and injection flow directions of the manufacturing process. To reach acceptable levels of accuracy, this inherent anisotropy needs to be correctly represented in the acoustical numerical simulation methodology. The present paper presents a methodology built on a hybrid combination of experimental deformation and strain field mapping, and physically based porous material acoustic Finite Element (FE) simulation modeling, allowing for the amsotropic dynamic elastic coefficients and damping properties of the foam to be correctly estimated. This new methodology of model-based porous material characterization is demonstrated here for a simplified seismic mass configuration.

  • 47.
    Guastavino, Remi
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Vibration Dynamics Modeling of Anisotropic Porous Foam Materials2005Konferansepaper (Fagfellevurdert)
    Abstract [en]

    For an accurate prediction of the low to medium frequency surface vibration and sound radiation behavior of multilayer trim components with polyurethane foam core materials, improved means of estimating the dynamic elastic and damping properties of the foam are necessary. This is due to the fact that in the manufactured porous polyurethane foam materials typically used in acoustic trim components, there is a geometric anisotropy in the foam cell microstructure. The foam cells and struts are elongated in the rise and injection flow directions of the manufacturing process. The density, elastic and damping properties of the foam can then be considered to be highly dependent upon manufacturing process techniques, along with the polyurethane chemical formulations. For a balanced cost and acoustic performance optimization of these materials in the product development cycle, it is important that this inherent anisotropy is correctly represented in the acoustical numerical simulation methodology. Through a hybrid combination of experimental deformation and strain field mapping, and physically based porous material acoustic Finite Element (FE) simulation modeling, the anisotropic dynamic elastic coefficients and damping properties of the foam may be correctly estimated. This new methodology of model-based porous material characterization is demonstrated here for a simplified seismic mass configuration. The improved accuracy of the subsequent low-mid frequency multilayer surface vibration numerical predictions is discussed. This leads to improved NVH analysis during the development lifecycle of the vehicle acoustic sound package, allowing a better balance between acoustic performance and a minimization of material usage to be achieved.

  • 48.
    Guastavino, Remi
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Hörlin, Nils-Erik
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Characterisation of anisotropic porous foam materials2005Konferansepaper (Annet vitenskapelig)
  • 49.
    Guastavino, Rémi
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    A 3D displacement measurement methodology for anisotropic porous cellular foam materials2007Inngår i: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 26, nr 6, s. 711-719Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents a new testing methodology for three dimensional (3D) full-field displacement mapping at the surface of elastic materials under static loading, here with a special focus on macroscopic behaviour of an anisotropic porous cellular foam. Three displacement components on four adjacent surfaces are estimated for cubic samples of the foam using a dual-camera 3D image correlation system. The critical feature of the proposed method is the provision made for efficient mapping of the four visible sides of the cubic sample, involving a rotating table and a common lateral reference frame. The overall setup used is described in some detail, together with the main steps of the measurement procedure and including remarks on the experience made during the development. Observations made concerning specific deformation phenomena occurring at discontinuities are discussed.

  • 50.
    Guastavino, Rémi
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    A methodology for identification of general orthotropic elastic models of porous foam2008Rapport (Annet vitenskapelig)
1234 1 - 50 of 162
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