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  • 51.
    Liu, Zibo
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Rumpler, Romain
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Feng, Leping
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Investigation of the sound transmission through a locally resonant metamaterial cylindrical shell in the ring frequency region2019In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 125, no 11, article id 115105Article in journal (Refereed)
    Abstract [en]

    Locally resonant metamaterial flat panels have proved to potentially exhibit extraordinary sound transmission loss properties when the resonance frequency of the resonators is tuned to the coincidence frequency region. Whether this technique is also effective to address the ring frequency effect for curved panels is investigated in this paper. For this purpose, a cylindrical shell, as a representation of curved panels, is studied from a theoretical and numerical point of view, with a specific focus on the transmission loss behaviour around the ring frequency region when the shell is mounted with local resonators. The influence from the resonators is presented and compared with that for a flat panel. An inverse effect of the resonators is observed on the sound transmission loss between the metamaterial cylindrical shell and the metamaterial flat panel when the resonance frequency of the resonators is tuned to be below or above the ring or coincidence frequency, respectively. Rather than the extraordinary improvement observed for the metamaterial flat panel, tuning such conventional resonators to the ring frequency of curved panels generates two side dips despite a sharp improvement at the ring frequency itself. This phenomenon is explained from an effective impedance point of view developed in this paper. The approach proposed and the conclusions provided may subsequently allow for the design of suitable resonators in order to resolve the ring frequency effect for curved panels.

  • 52.
    Liu, Zibo
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Rumpler, Romain
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Feng, Leping
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Investigation on the acoustic behaviour of a locally resonant metamaterial curved panel2018In: : Hiroshima Calling, ICSV 2018, Hiroshima, 2018, Vol. 6, p. 3409-3416Conference paper (Other academic)
    Abstract [en]

    In order to seek for new ways to improve the sound transmission loss at ring frequency range for curved aeronautical structures, a semi-infinite curved panel, representing aircraft fuselage, is studied in this research. First, a minor modification on Koval's classical theory for cylindrical shells is made to incorporate effective mass theory for acoustic metamaterials. Then, based on the finite element simulations, the possibility of improving the acoustic behaviour of such panels by using locally resonant acoustic metamaterial treatment is investigated. Both the host curved panel, and the host panel periodically mounted with local resonators, denoted as metamaterial curved panel, are compared from the transmission loss point of view. The observations show that the antiresonance dip appears first rather than the resonance peak in the sound transmission loss for the tested metamaterial curved panel, which may be explained by the effective impedance of the panel. The influences of the panel curvature on the dynamic behaviour of the local resonators are further discussed in comparison to the same resonantsystem acting on the flat panel. Both the finite element simulations and the theoretical estimations show the same trend, thus confirms the proposed explanation.

  • 53.
    Liu, Zibo
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Rumpler, Romain
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Feng, Leping
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Locally resonant metamaterial curved double wall to improve sound insulation at the ring frequency and mass-spring-mass resonanceIn: Article in journal (Refereed)
  • 54. Mehrgou, Mehdi
    et al.
    Jönsson, Ola
    Feng, Leping
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    On sound power measurement of the engine in anechoic room with imperfections2013In: 42nd International Congress and Exposition on Noise Control Engineering 2013, INTER-NOISE 2013: Noise Control for Quality of Life, OAL-Osterreichischer Arbeitsring fur Larmbekampfung , 2013, p. 4358-4364Conference paper (Refereed)
    Abstract [en]

    Engine noise is one of the most critical noises in urban noises. NVH improvements are essential in order to fulfill various noise emission regulations such as ISO 362. Reducing engine noise has become a necessity for engine developers. Measurement plays an important role beside the simulations to improve the NVH behavior, because the engine is a rather complicated mechanical system with many components. ISO 3745 is an ideal method for sound power measurement for internal combustion engines since it provides a fast measurement through many different engine speeds. However room as well as the measurement method, should comply with this standard. Because of the size and installation situation for a running engine there is limited space for measurement; and it is difficult to reach standards requirements especially for such a directive sound source. The difficulty to meet these requirements also applies to Scania's anechoic room. Here engine noise characteristics and the uncertainties in sound power measurement have been discussed based on both measurement and simulation. Recommendation has been made to decrease the uncertainty of sound power measurement.

  • 55. Nilsson, Anders
    et al.
    Liu, Bilong
    Feng, Leping
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Prediction of interior noise of a small aircraft2013In: 20th International Congress on Sound and Vibration 2013, ICSV 2013: Volume 1, 2013, Bangkok, Thailand: The International Institute of Acoustics and Vibration (IIAV) , 2013, p. 411-418Conference paper (Refereed)
    Abstract [en]

    The aim was to determine, already at the design stage, the interior noise level in a new small aircraft. The noise predictions were based on full-scale measurements on an existing model. A number of models for the prediction of velocity levels of a fuselage excited by turbulent boundary layers are discussed. Predicted results are compared to the result of in-flight measurements. It is found that the Corcos model gives the best agreement with the measured results. It is found that the velocity level of the plate elements of the fuselage very much depends on the speed of the aircraft. An increase of the speed by 10 % increases the plate velocity level by 3 dB. The velocity level is also strongly dependent on the plate thickness. An increase of the thickness by 50 % will decrease the velocity level by 5 dB. Small variations of other parameters like width and height and curvature of plate have only a very marginal effect on the plate velocity in the frequency range of interest. However, the acoustic power radiated into the aircraft cabin depends on the plate velocity of the fuselage as well the sound radiation properties of the plate structure. In the frequency, range of importance for the A-weighted noise level in the cabin the sound radiation ratio is increased as the plate thickness is increased. The noise level in the cabin is thus reduced much less than the velocity level of the fuselage by increasing the plate thickness. An increase of the width and length of plate elements reduces the sound intensity radiated by a plate. A combination of increased width and length and thickness of plate can result in a reduced noise radiation from the fuselage and thus in a reduced interior noise level.

  • 56. Orrenius, U.
    et al.
    Betgen, B.
    Feng, Leping
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Åbom, Mats
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Iglesias, E. Latorre
    Thompson, D.
    Brunström, S.
    Rail vehicle source assessment within a virtual certification process2014In: PROCEEDINGS OF INTERNATIONAL CONFERENCE ON NOISE AND VIBRATION ENGINEERING (ISMA2014) AND INTERNATIONAL CONFERENCE ON UNCERTAINTY IN STRUCTURAL DYNAMICS (USD2014), 2014, p. 3511-3525Conference paper (Refereed)
    Abstract [en]

    The present paper aims at giving an overview of the vehicle noise source modelling work carried out within the Acoutrain FP7 European research project. Results are presented for several areas including: equivalent source modelling concept applied to typical train sources, component based models for aero-acoustic noise generation of pantographs and installation effects of bogie and roof mounted sources. A process to characterize vehicle noise sources in an industrial context is presented. It is shown that equivalent monopole models, for which the source is described by a few monopoles, can be applied to represent real vehicle sources. It is also displayed how analytical models can be used to calculate the insertion loss of screens for sources that can be represented by point sources. Ray tracing and energy BEM models are used to determine the high frequency installation effect of a source in the bogie and a practical, procedure for in-situ testing of installation effects is suggested. For high speed applications a component based model is shown to accurately represent the spectrum of a train pantograph. It is concluded that the results to date are promising but more work is needed to validate the proposed process and methods for real vehicle installations in terms of modelling accuracy and usability in a virtual testing framework for TSI certification purposes.

  • 57. Orrenius, Ulf
    et al.
    Almgren, Martin
    Jiang, Yan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Flow acoustics.
    Feng, Leping
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Damping treatments on train interior panels: vibration and radiation effects2006In: Proceedings of the Joint Baltic-Nordic Acoustical Meeting, November 8-10, 2006, Gothenburg, Sweden, 2006Conference paper (Refereed)
  • 58. Piana, E. A.
    et al.
    Carlsson, Ulf
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Feng, Leping
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Determination and optimisation of the sound reduction index of ship bulkheads through the wave propagation approach2018In: 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, p. 4527-4541Conference paper (Refereed)
    Abstract [en]

    Lightweight composite structures are progressively replacing traditional materials like steel structures in the shipbuilding industry for their light weight and good mechanical characteristics. However, a lightweight composite structure has generally poor acoustic properties and is not suitable to shield noise. In this case some comfort issues may arise on board. Ships are also a source of underwater noise, which can seriously pollute the aquatic environment if a suitable form of shielding is not envisaged. It is therefore essential that some acoustic features are predicted and optimised. The paper presents the measurements carried out on two different types of bulkhead: a homogeneous ribbed fibreglass partition and a sandwich structure with two symmetrical fibreglass leaves plus a balsa core. The optimisation of such structures can be carried out following the simulations performed by using a code based on the wave propagation approach theory.

  • 59.
    Ramanathan, Sathish Kumar
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Feng, Leping
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Orrenius, Ulf
    Effects of damping treatments on acoustic properties of honeycomb panels2008Conference paper (Refereed)
    Abstract [en]

    Damping treatment is a common way to reducestructural vibration and as well as sound radiation. Inthis paper the effects of applying constrainedvisco-elastic damping treatment on lightweighthoneycomb structures are studied. Honeycomb panelsare well known for their high strength to weight ratiobut they rather possess poor acoustic transmissionproperties necessitating the use of additional dampinglayer treatments. However, although added damping isusually effective for vibration reduction it has oftenlittle effect on sound transmission. This paper comparesthe acoustic properties of honeycomb panels withdifferent core thicknesses and honey comb structuresthrough laboratory measurements. Constrainedvisco-elastic damping layers are tried on these panelsand a solution for a possible optimized dampingtreatment is studied.

  • 60.
    Ramanathan, Sathish Kumar
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Feng, Leping
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Orrenius, Ulf
    Modelling the sound transmission through rib-stiffened sandwich double-leaf partitions using space harmonic analysisIn: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568Article in journal (Other academic)
  • 61.
    Ramanathan, Sathish Kumar
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Feng, Leping
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Orrenius, Ulf
    Modelling the sound transmissionthrough rib-stiffened double-leaf partitions with cavity absorptionIn: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568Article in journal (Other academic)
  • 62.
    Ramanathan, Sathish Kumar
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Feng, Leping
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Orrenius, Ulf
    Predicting the sound transmission loss of honeycomb panels using the wave propagation approach2011In: Acta Acoustica united with Acustica, ISSN 1610-1928, E-ISSN 1861-9959, Vol. 97, no 5, p. 869-876Article in journal (Refereed)
    Abstract [en]

    The sound transmission properties of sandwich panels can be predicted with sufficient degree of accuracy by calculating the wave propagation properties of the structure. This method works well for sandwich panels with isotropic cores but applications to panels with anisotropic cores are hard to find. Honeycomb is an example of anisotropic material which when used as a core, results in a sandwich panel with anisotropic properties. In this paper, honeycomb panels are treated as being orthotropic and the wavenumbers are calculated for the two principle directions. These calculated wavenumbers are validated with the measured wavenumbers estimated from the resonance frequencies of freely hanging honeycomb beams. A combination of wave propagation and standard orthotropic plate theory is used to predict the sound transmission loss of honeycomb panels. These predictions are validated through sound transmission measurements. Passive damping treatment is a common way to reduce structural vibration and sound radiation, but they often have little effect on sound transmission. Visco-elastic damping with a constraining layer is applied to two honeycomb panels with standard and enhanced fluid coupling properties. This enhanced fluid coupling in one of the test panels is due to an extended coincidence range observed from the dispersion curves. The influence of damping treatments on the sound transmission loss of these panels is investigated. Results show that, after the damping treatment, the sound transmission loss of an acoustically bad panel and a normal panel are very similar.

  • 63.
    Ramanathan, Sathish Kumar
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Feng, Leping
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Orrenius, Ulf
    Transmission loss of rib-stiffened double-leaf partitions with cavity absorption2012Conference paper (Refereed)
  • 64.
    Song, Yubao
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Feng, Leping
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Liu, Zibo
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Wen, Jihong
    Yu, Dianlong
    Suppression of the vibration and sound radiation of a sandwich plate via periodic design2019In: International Journal of Mechanical Sciences, ISSN 0020-7403, E-ISSN 1879-2162, Vol. 150, p. 744-754Article in journal (Refereed)
    Abstract [en]

    This paper investigates the suppression of vibration and sound radiation of a sandwich plate through the use of periodic design. A periodic sandwich plate is constructed and its dispersion relation is calculated. The vibration and sound radiation properties of the periodic sandwich plate are studied. Via the comparison of the periodic and bare sandwich plate, the effects of the periodic design on the vibration and sound radiation are analysed. Further, to know the sound radiation properties better, sound radiation efficiency of the periodic and bare sandwich plates is compared. In addition, the effects of the boundary conditions on the properties of the periodic sandwich plate are analysed. The numerical results demonstrate that the vibration and sound radiation are greatly suppressed over the stop band of the periodic sandwich plate. The suppression can also be obtained in part of pass bands. It is also shown that the periodic design can be an effective method for the reduction of the sound radiation efficiency. The suppression for the vibration and sound is greater than that caused by only increasing the mass of the plate in the designing frequency range.

  • 65.
    Song, Yubao
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Vibration monitoring. National University of Defense Technology, China.
    Feng, Leping
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Vibration monitoring.
    Wen, J.
    Yu, D.
    Wen, X.
    Reduction of the sound transmission of a periodic sandwich plate using the stop band concept2015In: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 128, p. 428-436Article in journal (Refereed)
    Abstract [en]

    The sound transmission of a sandwich plate and its reduction using the stop band concept are investigated in this paper. A periodic sandwich plate consisting of a host plate and the attached structures is designed. The dispersion relation and the stop band of the periodic sandwich plate are studied first. The sound transmission of the periodic and bare sandwich plates is analysed and compared. The reduction from the stop band design (i.e., periodically adding stepped resonators) on the sound transmission of the sandwich plates is studied. The reasons for this reduction are analysed. In addition, the properties of the sandwich plate with different boundary conditions are also briefly studied. The numerical results indicate that the sound transmission is significantly reduced over the stop band of the periodic sandwich plate. The improvement can also exist in the frequency range outside the stop band.

  • 66.
    Song, Yubao
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. National University of Defense Technology, People's Republic of China .
    Feng, Leping
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Wen, Jihong
    Yu, Dianong
    Wen, Xisen
    Analysis and enhancement of flexural wave stop bands in 2D periodic plates2015In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 379, no 22-23Article in journal (Other academic)
    Abstract [en]

    The band structure and enhancement of flexural wave stop bands in a 2D periodic plate are investigated. A unified method for analysing and designing the stop band of the plates with various attached structures is proposed. The effect of attached structures is considered based on their equivalent parameters (added equivalent mass and equivalent moment of inertia). The influences of the equivalent parameters on the band structures are studied. Three cases are considered: adding pure equivalent mass, pure equivalent moment of inertia and the combination of these two. The stop bands are enhanced via the multi interaction between the host plate and the attached structure. The enhancement pattern is determined, and several ways to obtain a wider combined stop band are presented. The frequency response functions of corresponding finite periodic plates are calculated to verify the stop bands and their enhancement in a number of typical cases.

  • 67.
    Zea, Elias
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Manzari, Luca
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Squicciarini, Giacomo
    University of Southampton, Institute of Sound and Vibration Research.
    Feng, Leping
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Thompson, David
    University of Southampton, Institute of Sound and Vibration Research.
    Lopez Arteaga, Ines
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. Eindhoven University of Technology, Department of Mechanical Engineering.
    Wavenumber-domain separation of rail contribution to pass-by noise2017In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 409, p. 24-42Article in journal (Refereed)
    Abstract [en]

    In order to counteract the problem of railway noise and its environmental impact, passing trains in Europe must be tested in accordance to a noise legislation that demands the quantification of the noise generated by the vehicle alone. However, for frequencies between about 500 Hz and 1600 Hz, it has been found that a significant part of the measured noise is generated by the rail, which behaves like a distributed source and radiates plane waves as a result of the contact with the train's wheels. Thus the need arises for separating the rail contribution to the pass-by noise in that particular frequency range. To this end, the present paper introduces a wavenumber–domain filtering technique, referred to as wave signature extraction, which requires a line microphone array parallel to the rail, and two accelerometers on the rail in the vertical and lateral direction. The novel contributions of this research are: (i) the introduction and application of wavenumber (or plane–wave) filters to pass-by data measured with a microphone array located in the near-field of the rail, and (ii) the design of such filters without prior information of the structural properties of the rail. The latter is achieved by recording the array pressure, as well as the rail vibrations with the accelerometers, before and after the train pass-by. The performance of the proposed method is investigated with a set of pass-by measurements performed in Germany. The results seem to be promising when compared to reference data from TWINS, and the largest discrepancies occur above 1600 Hz and are attributed to plane waves radiated by the rail that so far have not been accounted for in the design of the filters.

12 51 - 67 of 67
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