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  • 1.
    Gaborit, Mathieu
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Dazel, O.
    Göransson, Peter
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Influence of uncertain parameters on the acoustic behaviour of sound proofing laminates2019In: INTER-NOISE 2019 MADRID - 48th International Congress and Exhibition on Noise Control Engineering, SOCIEDAD ESPANOLA DE ACUSTICA - Spanish Acoustical Society, SEA , 2019Conference paper (Refereed)
    Abstract [en]

    The protection against excessive noise has gathered a lot of attention along the years. Tailored solutions for specific types of noise conditions emerged and many communications on the subject are published every year. Although designing sound proofing systems is a well developed topic, building the proposed systems is still subject to many uncertainties. For instance, the very nature of the foams used in many broadband absorbers implies a degree of uncertainty on some of the most important parameters (e.g. the airflow resistivity). This phenomenon is even more noticeable in modern sound absorbing laminates in which every interface implies a barely controllable change in the continuity conditions. This effect being rarely accounted for and the interfaces' properties hard to quantify, it adds uncertainties that are widely neglected even though having a potentially strong impact. In this contribution, the effect of randomly distributed parameters on the overall acoustic response of multi-layer systems is considered. The influence of choosing specific acoustic models for each layer is emphasized and the resulting response envelope is studied.

  • 2.
    Ilkka, Karasalo
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL.
    Tengzelius, U.
    Assessment of a simplified environmental model for aircraft noise prediction2019In: INTER-NOISE 2019 MADRID - 48th International Congress and Exhibition on Noise Control Engineering, SOCIEDAD ESPANOLA DE ACUSTICA - Spanish Acoustical Society, SEA , 2019Conference paper (Refereed)
    Abstract [en]

    The environmental effects on the noise level on the ground from aircraft near the Arlanda airport are studied by numerical predictions of the acoustic transfer function from the aircraft position to the ground. Sound propagation is modelled by acoustic ray tracing using time-variable 3D atmospheric fields provided by the AROME prognosis model, combined with 2D data on ground topology and ground cover. The acoustic transfer function from selected points on the flight path to the ground is computed as function of range to the ground track at two-hour intervals during a one-year period. The results, aggregated into percentiles of the transfer function, are compared to similarly aggregated results from a simplified model of the atmosphere, the ground and the sound propagation. The simplifications are introduced to reduce the computational demands, are: (i) the ground is flat, (ii) the atmospheric parameters are functions of height only and (iii) rays are not continued beyond their first ground hit.

  • 3.
    Lopez Arteaga, Ines
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL. Eindhoven University of Technology, Department of Mechanical Engineering, Eindhoven, Netherlands.
    Rolling noise in road and rail transportation systems2019In: INTER-NOISE 2019 MADRID - 48th International Congress and Exhibition on Noise Control Engineering, SOCIEDAD ESPANOLA DE ACUSTICA - Spanish Acoustical Society, SEA , 2019Conference paper (Refereed)
    Abstract [en]

    Long term exposure to ground transportation (road and rail traffic) noise is, after air pollution, the main environment-related health stressor in densely populated areas and compromises the quality of life and, indirectly, the life expectations of millions of people. The main source of ground transportation noise at speeds up to 130 km/h in road traffic and up to 300 km/h in rail traffic is rolling noise; noise generated due to the interaction between tyre and road (respectively wheel and rail). Although at first sight noise generation in these two transportation systems might seem unrelated, exploring the common aspects provides valuable insight in current practices for the modeling, prediction and abatement of rolling noise. In this paper the sound and vibration generation mechanisms due to tyre/road and wheel/rail interaction are discussed, focusing on the similarities and differences between the sound and vibration generation mechanisms in these two systems. This perspective is further extended to the discussion of modelling strategies and source characterization methods, with a particular emphasis on the influence of surface roughness on contact force generation. Finally, rolling noise source separation methods are touched upon, since they are a necesary tool to assess the impact of noise and vibration mitigation measures in both road and rail traffic systems.

  • 4.
    Mao, Huina
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Rumpler, Romain
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL.
    Göransson, Peter
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    An inverse method for characterisation of the static elastic Hooke's tensors of solid frame of anisotropic open-cell materials2020In: International Journal of Engineering Science, ISSN 0020-7225, E-ISSN 1879-2197, Vol. 147, article id 103198Article in journal (Refereed)
    Abstract [en]

    This paper proposes an inverse estimation method for the extraction of the equivalent, static elastic, Hooke's tensor. The inversion is based on a fitting of the displacements, obtained from a combination of static compression and shear traction loads, on the faces of a sample specimen. An equivalent, homogenised material model is found by varying the elastic moduli until a defined cost function, based on the error measured as the difference between the displacement fields, has reached a minimum, at which an anisotropic constitutive solid model has been identified. The method is built on a multi-level step-wise approach, both from a computational as well as an assumed constitutive model symmetry point of view. The principle of the method is validated for a target anisotropic solid material model. The proposed multi-level approach is developed and refined for a known open-cell structure based on the Kelvin cell geometry. The accuracy of the method is verified and various strategies for increasing the rate of convergence in the inversion are discussed.

  • 5.
    Rumpler, Romain
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL.
    Rodrı́guez Sánchez, Raúl
    Chair of Structural Mechanics, Technical University of Munich.
    Göransson, Peter
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    MULTIVARIATE PADÉ APPROXIMANTS FOR FINITE ELEMENT SOLUTIONS WITH COMPLEX PARAMETRIC DEPENDENCE2019Conference paper (Refereed)
    Abstract [en]

    Most engineering applications involving solutions by numerical methods are dependent on several parameters, whose impact on the solution may significantly vary from one to the other. At times an evaluation of these multivariate solutions may be required at the expense of a prohibitively high computational cost. In the present work, a multivariate finite element approach is proposed, allowing for a fast evaluation of parametric responses. It is based on the construction of a reduced basis spanning a subspace able to capture rough variations of the response. The method consists in an extension of the Well-Conditioned Asymptotic Waveform Evaluation (WCAWE) to multivariate problems, by an appropriate choice of derivative sequences, and a selection of the most relevant basis components. It is validated and demonstrated for its potential on a semi-industrial sized 3D application involving coupled poroelasticand internal acoustic domains.

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  • 6.
    Wang, Bochao
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL.
    Constitutive models of magneto-sensitive rubber under a continuum mechanics basis and the application in vibration isolation2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Due to its durability, stretchability, relatively low stiffness and high damping, rubber is widely used in engineering anti-vibration fields. However, a major deficiency is that once installed, the mechanical properties of traditional rubber-based devices are fixed where its adaptability to various loading conditions is poor. An alternative to traditional rubber materials is magneto-sensitive (MS) rubber. The main componentsof MS rubber are a rubber matrix and ferromagnetic particles. Under a magnetic field, the modulus of MS rubber can be altered rapidly and reversibly. Therefore, compared with conventional rubber-based devices, the stiffness of MS rubber-based devices can be adapted to various loading conditions and an enhanced vibration reduction effect can be achieved. Measurement results revealed that the mechanical behavior of MS rubber is not simple. To be specific, the dynamic modulus of MS rubber has a magnetic, frequency,amplitude and temperature dependency. In order to promote the applications of MS rubber in the anti-vibration area, models to depict the above properties are needed. The main goal of this thesis is to model the magnetic, frequency, amplitude and temperature dependence of MS rubber under a continuum mechanics basis. The research results regarding the constitutive modeling consist of three papers (Paper A, C and D). The simulation results show a good agreement with the measurement data, which proves the accuracy and feasibility of the developed model. In addition to the constitutive models of MS rubber, an investigation of MS rubber application in the vibration isolation system under harmonic and random loading cases is numerically conducted (Paper B). In order to achieve an enhanced vibration isolation effect, two control algorithms corresponding to the harmonic and random loading are developed. Numerical results verify that the vibration isolation effect ofMS rubber vibration isolator is better than the traditional rubber-based isolator. In this thesis, the model developed for MS rubber deepens the understanding of how magnetic, frequency, amplitude and temperature affect the mechanical performance of MS rubber. Moreover, the research of MS rubber application in vibration isolators and the corresponding control strategies are helpful for the design of MS rubber-based anti-vibration devices.

    Download full text (pdf)
    Constitutive models of magneto-sensitive rubber under a continuum mechanics basis and the application in vibration isolation
  • 7.
    Wang, Bochao
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL.
    Kari, Leif
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL.
    A visco-elastic-plastic constitutive model of isotropic magneto-sensitive rubber with amplitude, frequency and magnetic dependency2020In: International journal of plasticity, ISSN 0749-6419, E-ISSN 1879-2154Article in journal (Refereed)
    Abstract [en]

    A three-dimensional visco-elastic-plastic constitutive model of isotropic magneto-sensitive (MS) rubber with amplitude, frequency and magnetic dependency under a continuum constitutive framework is developed. MS rubber is akind of smart material mainly composed of a rubber matrix and magnetizable particles. Under a magnetic field, there is an increase of its dynamic modulus due to the interaction between the magnetic field and MS rubber, which is often referred to as the magnetic dependency of MS rubber. Experimental results reveal that besides the magnetic dependency, there is a frequency and amplitude dependency of its dynamic modulus. In specific, the modulus of MS rubber increases with increasing frequency and dereases with increasing strain amplitude. To depict the above properties and to consider the balance of energy in continuum mechanics framework, a new constitutive model consisting of a viscoelastic fractional derivative element, a bounding surface model in series with a neo-Hookean elastic model with magnetic sensitivity and a magnetic stress tensor term for MS rubber is proposed. The contribution of this constitutive model is that by using a free energy based method, with only eight material parameters, the amplitude, frequency and magnetic dependency of MS rubber can be reflected. After parameter identification, the simulationresults show a good agreement with those of measurements. Therefore, by utilizing the model proposed, the ability of approaching the dynamic behavior of MS rubber-based vibration reduction devices in the design phase is possible which contributes to the application of MS rubber in noise and vibration reduction area.

  • 8.
    Wang, Bochao
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL.
    Kari, Leif
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL.
    Constitutive model of isotropic magneto-sensitive rubber with amplitude, frequency, magnetic and temperature dependence under a continuum mechanics basis2020In: International Journal of Engineering Science, ISSN 0020-7225, E-ISSN 1879-2197Article in journal (Other academic)
    Abstract [en]

    A three-dimensional nonlinear constitutive model of the amplitude, frequency, magnetic and temperature-dependent mechanical properties of isotropic magneto-sensitive (MS) rubber is developed. The main components of MS rubberis an elastomer matrix and magnetizable particles. When a magnetic field is applied, the modulus of MS rubber increases, which is known as the magnetic dependence of MS rubber. In addition to the magnetic dependence, there arefrequency, amplitude and temperature dependencies of MS rubber. Specifically, a higher frequency, a smaller strain amplitude and a lower temperature lead to an increased magnitude of the dynamic modulus. To represent the above properties and to stimulate the possible application of MS rubber in the anti-vibration area, a continuum mechanic framework based constitutive model consisting of a fractional standard linear solid (SLS) element, an elastoplastic element and a magnetic stress term of MS rubber is developed. The frequency and amplitude dependencies are depicted by a fractional SLS element and an elastoplastic element, respectively. A hyperbolic tangent function with a scalar product of magnetic flux density as an independent variable is introduced to consider the magnetic dependence. Furthermore, the temperature dependence is taken into account by including the William-Landel-Ferry function and the Arrhenius function to the fractional SLS element and the elastoplastic element, respectively. The technical innovation of this constitutive model is that the amplitude, frequency, magnetic and temperature dependent mechanical properties of MS rubber are incorporated into a whole constitutive model under the continuum mechanics frame and based on the free energy assumption. Comparison between the simulation and measurement results in a wide frequency range with different levels of magnetic field, strain amplitude and temperature shows that the fitting effect of the developed model is very good. Therefore, the constitutive model proposed in this paper enables the prediction ofthe mechanical properties of MS rubber under various operating conditions with high accuracy, which will drive MS rubber’s application in engineering applications, especially in the area of MS rubber-based anti-vibration devices.

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