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  • 1.
    Barbagallo, Mathias
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Finnveden, Svante
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Liu, Hao
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Statistical energy analysis of the sound transmission through layered panels using a variational formulation of the porous materialArticle in journal (Other academic)
  • 2.
    Bennett, Gareth J.
    et al.
    Trinity College Dublin, Department of Mechanical and Manufacturing Engineering, Ireland.
    O'Reilly, Ciarán J.
    Trinity College Dublin, Department of Mechanical and Manufacturing Engineering, Ireland.
    Liu, Hao
    Trinity College Dublin, Department of Mechanical and Manufacturing Engineering, Ireland.
    Tapken, Ulf
    DLR, German Aerospace Center, Germany.
    Modelling multi-modal sound transmission from point sources in ducts with flow using a wave-based method2009In: 16th International Congress on Sound and Vibration, ICSV16, 2009, Vol. 8, p. 4685-4693Conference paper (Other academic)
    Abstract [en]

    An understanding of the multi-modal propagation of acoustic waves in ducts is of practical interest for use in the control of noise in, for example, aero-engines, automotive exhaust and ventilation systems. In this paper, the propagation of sound from point sources in hard-walled ducts is modelled using a numerical wave-based approach, referred to as the wave expansion method. This is a highly efficient full-domain discretisation method, which requires as few as two-to-three mesh points per wavelength. An inhomogeneous potential flow may be easily included in the method. The numerical solution for point sources embedded in the wall of a circular duct with non-reflective end-conditions and a uniform axial flow is compared with an analytical Green's function solution. A modal decomposition technique is used to provide detailed information about the modal content of the sound field. This study provides an insightful comparison between an analytical and numerical solution to the acoustic field in a duct. The accuracy and robustness of the wave expansion method is assessed for this benchmark problem before its versatility is demonstrated with examples.

  • 3.
    Finnveden, Svante
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Hao, Liu
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Chap 8, Waveguide Finite Element Method2012In: Mid-Frequency, CAE Methodologies for Mid-Frequency Analysis in Vibration and Acoustics / [ed] Wim Desmet, Bert Pluymer, Onur Atak, Leuven: KUL , 2012Chapter in book (Other academic)
  • 4.
    Liu, Hao
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Wave Modelling Techniques for Medium and High Frequency Vibroacoustic Analysis Including Porous Materials2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Numerical methods based on wave modelling are explored for the vibroacoustic analysis of wave propagation, sound transmission and interior noise in vehicles and buildings at medium and high frequencies. The presence of sound absorbing porous materials in practical engineering structures is also considered. The wave modelling techniques provide computational efficiency and physical insight, and two such methods having these advantages are developed in this thesis namely: the semi-analytical finite element method and the wave expansion method.

    The semi-analytical finite element method is applicable to structures which have constant properties in one direction, and it uses a finite element discretization of the cross-section and analytical functions in the third direction. Equations of motion are derived from this method to study wave propagation characteristics, which help understand the vibroacoustic behavior of structures. These characteristics may also be used by high frequency techniques, such as statistical energy analysis. The wave propagation in sandwich panels with a poroelastic core, which is modeled with Biot's theory, is investigated thoroughly.

    The semi-analytical finite element method retains the flexibility of the finite element method on geometry and also dramatically increases the computational speed thanks to the orthogonality of the analytical functions when used to calculate forced response. The calculated response of partitions is integrated into diffuse field sound transmission loss calculations of, for example, built-up train floor partitions and multilayer panels lined with porous materials. The calculations are computationally efficient and show good agreement with measurements, thus it is interesting for industrial optimizations.

    The wave expansion method uses a priori defined plane wave solutions to the Helmholtz equation for approximation of the sound field in geometrically complex enclosures. It reduces the requirements regarding the number of degrees of freedom compared to the finite element method, which, furthermore, is polluted by dispersion errors. Therefore, the wave expansion method is particularly appealing for high frequency (or large wavenumber) calculations. Its application in interior sound field predictions is assessed within the automobile context.

  • 5.
    Liu, Hao
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Barbagallo, Mathias
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Finnveden, Svante
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Wave motion and sound transmission loss of double walls filled with porous materials2012In: Proceedings Of International Conference On Noise And Vibration Engineering (ISMA2012) / International Conference On Uncertainty In Structural Dynamics (USD2012), 2012, p. 1803-1814Conference paper (Refereed)
    Abstract [en]

    A novel semi-analytical approach is presented and employed to calculate the sound transmission loss (STL) of a double wall lined with porous materials. The approach consists of using the waveguide finite element method (WFEM) together with a Rayleigh-Ritz procedure. The former is a convenient semi-analytical approach useful for structures having constant properties along one direction. The Rayleigh-Ritz procedure assumes that the structure satisfies convenient boundary conditions, so that its response can be described by a trigonometric Fourier series. The advantage of the procedure compared to full FE models, and spectral element models, is that it evaluates several orders of magnitude quicker and can describe frequency dependent materials at virtually no cost. In addition, the WFEM readily provides the dispersion curves of the structure, which reveal its physics. Calculations of the STL are favourably compared to measurements.

  • 6.
    Liu, Hao
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Finnveden, Svante
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Barbagallo, Mathias
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Lopez Arteaga, Ines
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Wave propagation in sandwich panels with a poroelastic core2014In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 135, no 5, p. 2683-2693Article in journal (Refereed)
    Abstract [en]

    Wave propagation in sandwich panels with a poroelastic core, which is modeled by Biot's theory, is investigated using the waveguide finite element method. A waveguide poroelastic element is developed based on a displacement-pressure weak form. The dispersion curves of the sandwich panel are first identified as propagating or evanescent waves by varying the damping in the panel, and wave characteristics are analyzed by examining their motions. The energy distributions are calculated to identify the dominant motions. Simplified analytical models are also devised to show the main physics of the corresponding waves. This wave propagation analysis provides insight into the vibro-acoustic behavior of sandwich panels lined with elastic porous materials.

  • 7.
    Liu, Hao
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Finnveden, Svante
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Lopez Arteaga, Ines
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Prediction of sound transmission through elastic porous material lined multilayer panels using a semi-analytical finite element methodManuscript (preprint) (Other academic)
  • 8.
    Liu, Hao
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    O'Reilly, Ciarán
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Finnveden, Svante
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Lopez Arteaga, Ines
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Prediction of sound field in geometrically complex enclosures with the wave expansion methodManuscript (preprint) (Other academic)
  • 9. Orrenius, Ulf
    et al.
    Liu, Hao
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Wareing, Andrew
    Finnveden, Svante
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Cotoni, Vincent
    Wave modelling in predictive vibro-acoustics: Applications to rail vehicles and aircraft2014In: Wave motion, ISSN 0165-2125, E-ISSN 1878-433X, Vol. 51, no 4, p. 635-649Article in journal (Refereed)
    Abstract [en]

    Three different predictive methods based on wave descriptions of the acoustic field are presented and used to calculate transmission and radiation properties of typical rail and aerospace structures. First, a transfer matrix method assesses the sound transmission and wavenumbers of composite sandwich fuselage structures in a wide frequency range. The method is computationally effective and can be used for numerical optimization of sandwich lay-ups common in rail and aerospace engineering. Further, an approach for which a small finite element model of a periodic cell is applied to create a statistical model of a near periodic structure is shown to determine transmission and radiation properties of stiffened fuselage structures and an extruded train floor structure. Finally, a novel combination of the waveguide FE method with the Rayleigh-Ritz method is applied to: (i) calculate the transmission through a double wall structure; (ii) again assess the sound transmission of an extruded floor structure and also (iii) determine the sound pressure inside a large section of a rail car excited by external sound sources. All three methods presented can be used to effectively support decision making in the design process of trains and aircraft.

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