| 1. |
- Nygren, Johan, et al.
(författare)
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An investigation of allocation strategies for internalizing the impact from traffic noise
- 2020
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Ingår i: Proceedings of ISMA 2020 - International Conference on Noise and Vibration Engineering and USD 2020 - International Conference on Uncertainty in Structural Dynamics. - : Katholieke Universiteit Leuven. Department of Mechanical Engineering. Celestijnenlaan 300B - box 2420. B-3001 Heverlee (Belgium).. ; , s. 2395-2404
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Konferensbidrag (refereegranskat)abstract
- Adverse health effects related to exposure to traffic noise poses a challenge for future transport demand. To reduce the exposure of noise, and in turn reduce the health impact, the present study investigates different allocation strategies of an overall traffic noise-related cost down to individual vehicles in a microscopic traffic simulation in SUMO. Two allocation concepts were analysed. The first concept proposed cost allocation only to timesteps where the overall noise level exceeds a certain threshold. This resulted in lower cost for vehicles driving in the road network at off-peak times. The second concept introduced a non-linear scaling to shift cost either towards noisier vehicles at each timestep or toward timesteps with more noise than other timesteps. This allocation strategy showed potential to reflect the system-level effect of traffic noise to the individual vehicles in the network.
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| 2. |
- Nygren, Johan, et al.
(författare)
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Vehicle-specific noise exposure cost : Noise impact allocation methodology for microscopic traffic simulations
- 2023
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Ingår i: Transportation Research Part D. - : Elsevier BV. - 1361-9209 .- 1879-2340. ; 118, s. 103712-103712
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Tidskriftsartikel (refereegranskat)abstract
- This paper proposes a methodology in traffic noise assessment, whose objective is to combine microscopic traffic simulations and noise calculation methods with macro-level, systemic noise impact assessment models. This combination, referred to as the vehicle-specific noise exposure cost (NEC), provides a per-vehicle contribution to the overall noise impact. Three case studies are introduced illustrating the potential of the methodology: a reference case with a dynamic traffic flow, the correlation between vehicle-specific NECs and average speeds, and vehicle-specific NECs in a mixed traffic fleet. The results highlight the interest and importance of using a microscopic approach, as the impact of interactions, vehicle-specific characteristics and behaviors are reflected into the associated NECs. Additionally, the correlation between vehicle-specific NECs and average speeds strongly depends on traffic conditions, further highlighting the importance of methodological features such as the interactions captured in microscopic traffic simulations or the acceleration-dependency of the implemented vehicle noise source model.
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| 3. |
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Proceedings of the Resource Efficient Vehicles Conference - 2021 (rev2021)
- 2021
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Proceedings (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- rev2021 was the first edition of the conference on Resource Efficient Vehicles, held online on 14-16 June 2021. This vehicle-centric conference aims to bring together participants from academia, industry and public agencies to discuss research from all relevant fields connected to resource efficiency in all motorised modes of transport and interdependent surrounding systems. The theme of this multidisciplinary conference is Resolving Functional Conflicts in Vehicle Design, a theme explored through topics including modelling for multifunctional design; making trade-offs; efficient use of materials and space; integrating new solutions; transforming the product system; transforming the vehicle-transport system; sustainable design; and early-stage design. The 2021 edition of the conference consisted of 40 selected papers for presentation at the conference, complemented with four workshops, five keynote lectures from invited speakers, and a concluding panel discussion with four invited participants. It was organised by the Centre for ECO2 Vehicle Design at KTH Royal Institute of Technology in Stockholm.
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| 4. |
- Baclet, Sacha, et al.
(författare)
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A methodology to assess the impact of driving noise from individual vehicles in an urban environment
- 2021
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Ingår i: "Advances in Acoustics, Noise and Vibration - 2021" Proceedings of the 27th International Congress on Sound and Vibration, ICSV 2021.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Traffic is a major source of environmental noise pollution in urban areas. The present contribution focuses on a methodology designed to assess the impact of the noise generated by individual vehicles on a city's population using NoiseModelling, an open-source library implementing the CNOSSOS-EU model, capable of producing environmental noise maps. The initial step of the proposed method consists in processing microscopic traffic data (simulated in the present contribution), where the traffic intensity is dependent on the time of day that is targeted. The micro-traffic data is subsequently used to generate background noise maps by simulating the propagation of traffic noise. Then, the impact of the noise from the vehicle of interest is simulated, based on several parameters (route followed, type of motorization: diesel or hybrid, etc.). Finally, the data is post-processed to calculate the "exceedance" (increase in ambient noise) caused by the vehicle, taking the previously calculated background noise maps as reference. The complete methodology, its underlying assumptions, and the associated criteria proposed in order to assess the impact of noise emissions from individual vehicles is demonstrated on a realistic scenario.
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| 5. |
- Baclet, Sacha, et al.
(författare)
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From strategic noise maps to receiver-centric noise exposure sensitivity mapping
- 2022
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Ingår i: Transportation Research Part D. - : Elsevier BV. - 1361-9209 .- 1879-2340. ; 102, s. 103114-103114
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Tidskriftsartikel (refereegranskat)abstract
- Road traffic is a major source of environmental noise pollution in urban areas. While strategic noise maps are widely used to identify the critical areas and propose mitigation plans, more specific tools are needed to evaluate the impact from traffic noise such as overall population exposure or anticipated impact from specific vehicles in varying spatiotemporal traffic conditions.The present contribution proposes a receiver-centric mapping approach, introducing “noise-exposure sensitivity maps”, meant to assess the potential noise exposure impact from a specific vehicle in a given network, quantifying the associated exceedance over the prevailing background noise, under varying spatiotemporal traffic conditions. The resulting maps are thus focussed on a representation of the receiver exposure as opposed to considering the noise emission and propagation alone.The complete methodology, its underlying assumptions, and possible applications such as route optimisation are demonstrated on realistic scenarios.
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| 6. |
- Baclet, Sacha, et al.
(författare)
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Near-real-time dynamic noise mapping and exposure assessment using calibrated microscopic traffic simulations
- 2023
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Ingår i: Transportation Research Part D. - : Elsevier BV. - 1361-9209 .- 1879-2340. ; 124
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Tidskriftsartikel (refereegranskat)abstract
- With prospective applications ranging from improving the understanding of the daily and seasonal dynamics of noise exposure to raising public awareness of the associated health effects, dynamic noise mapping in real time is one of the next milestones in environmental acoustics. The present contribution proposes a methodology for near-real-time dynamic noise mapping, enabling the generation of dynamic noise maps and the calculation of advanced noise exposure indicators, here arbitrarily established for the previous day, on the scale of large urban areas. This methodology consists in (i) collecting live traffic counts, measured using dedicated IoT sensors, (ii) calibrating a microscopic traffic simulation using these sparsely distributed traffic counts, (iii) modelling noise emission and propagation from the microscopic traffic simulation, and finally, (iv) post-processing the noise simulation output for the calculation of a wide range of exposure indicators. The applicability of the method is demonstrated on the city of Tartu, Estonia.
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| 7. |
- Barderi, Rita Caminal, et al.
(författare)
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Development of Methods for Virtual Exterior Noise Validation
- 2024
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Ingår i: Noise and Vibration Mitigation for Rail Transportation Systems - Proceedings of the 14th International Workshop on Railway Noise, 2022. - : Springer Nature. ; , s. 63-71
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Konferensbidrag (refereegranskat)abstract
- Simulating the exterior noise levels created by the train equipment requires a good representation of the equipment integration, the noise propagation, the ground reflection and, for some cases, the diffraction in the different train surfaces. In the framework of the European project Shift2Rail program S2R-CFM-CCA-01-2019 Energy and Noise and Vibration, the state-of-the-art of the exterior noise of rolling stock vehicle simulation is being compared between railway manufacturers and oper-ators and the advanced techniques proposed by the consortium Open Call project S2R-OC-CCA-01-2019 (TRANSIT https://transit-prj.eu). With respect to previous work done in the same direction (ACOUTRAIN https://cordis.europa.eu/project/id/284877/reporting/es, SILENCE http://www.silence-ip.org,FINE-1 https://projects.shift2rail.org/s2r_ipcc_n.aspx?p=FINE%201), the focus of the work is on the train integration effects of equipment in a rolling stock.
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| 8. |
- de Conchard, Antoine Vermeil, et al.
(författare)
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A perfectly matched layer formulation adapted for fast frequency sweeps of exterior acoustics finite element models
- 2019
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Ingår i: Journal of Computational Physics. - : ACADEMIC PRESS INC ELSEVIER SCIENCE. - 0021-9991 .- 1090-2716. ; 398
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Tidskriftsartikel (refereegranskat)abstract
- Effective treatment of unbounded domains using artificial truncating boundaries are essential in numerical simulation, e.g. using the Finite Element Method (FEM). Among these, Perfectly Matched Layers (PML) have proved to be particularly efficient and flexible. However, an efficient handling of frequency sweeps is not trivial with such absorbing layers since the formulation inherently contains coupled space-and frequency-dependent terms. Using the FEM, this may imply generating system matrices at each step of the frequency sweep. In this paper, an approximation is proposed in order to allow for efficient frequency sweeps. The performance and robustness of the proposed approximation is presented on 2D and 3D acoustic cases. A generic, robust way to truncate the acoustic domain efficiently is also proposed, tested on a range of test cases and for different frequency regions. All rights reserved.
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| 9. |
- Gaborit, Mathieu, et al.
(författare)
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Towards fully controlled anisotropy in cellular porous media : An overview
- 2021
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Ingår i: Proceedings of INTER-NOISE 2021 - 2021 International Congress and Exposition of Noise Control Engineering. - : Institute of Noise Control Engineering (INCE). ; , s. 5253-5259
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Konferensbidrag (refereegranskat)abstract
- In the recent years, our team has been working to identify key aspects of anisotropy in porous media. More than just characterising their anisotropic properties, we're interested in generating cellular media with completely designed anisotropic properties. The results of these studies have partly been published and more are to come. In this presentation, we'll present an overview of this work and how it ultimately ties to acoustics. We will introduce the key findings,discussed specific results that can be achieved and provide context and details related to the strategy developed to address the tasks.
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| 10. |
- Kleine-Wächter, Lukas, et al.
(författare)
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Numerical study of Kelvin cells for the design of periodic lattice metamaterials
- 2022
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Ingår i: Proceedings of ISMA 2022 - International Conference on Noise and Vibration Engineering and USD 2022 - International Conference on Uncertainty in Structural Dynamics. - : KU Leuven, Departement Werktuigkunde. ; , s. 2960-2974
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Konferensbidrag (refereegranskat)abstract
- Artificially-composed materials, often called metamaterials, are an increasingly considered measure for vibration control. By carefully arranging the material micro-structure, significant vibration attenuation is achievable in targeted frequency bands from resonant and wave scattering effects. An approach in designing materials for vibration control are micro-structures assembled from periodic cellular lattices. Such architectures result from the spatial repetition of cellular units that can be dynamically tuned by controlling the lattice characteristics. This contribution investigates the prospects of a three-dimensional lattice structure for application in vibration control. A unit cell design strategy is proposed based on the isometric Kelvin cell. By imposing twists on the faces of the Kelvin cell, a potential tuning mechanism for the cell's dispersive properties is introduced. Selected unit cell designs obtained from this approach are investigated in terms of the dispersion characteristics of 1D-infinite structures.
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| 11. |
- Koch, Sarah, et al.
(författare)
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Impacts of changes in environmental exposures and health behaviours due to the COVID-19 pandemic on cardiovascular and mental health : A comparison of Barcelona, Vienna, and Stockholm
- 2022
-
Ingår i: Environmental Pollution. - : Elsevier BV. - 0269-7491 .- 1873-6424. ; 304
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Tidskriftsartikel (refereegranskat)abstract
- Responses to COVID-19 altered environmental exposures and health behaviours associated with noncommunicable diseases. We aimed to (1) quantify changes in nitrogen dioxide (NO2), noise, physical activity, and greenspace visits associated with COVID-19 policies in the spring of 2020 in Barcelona (Spain), Vienna (Austria), and Stockholm (Sweden), and (2) estimated the number of additional and prevented diagnoses of myocardial infarction (MI), stroke, depression, and anxiety based on these changes. We calculated differences in NO2, noise, physical activity, and greenspace visits between pre-pandemic (baseline) and pandemic (counterfactual) levels. With two counterfactual scenarios, we distinguished between Acute Period (March 15th - April 26th, 2020) and Deconfinement Period (May 2nd - June 30th, 2020) assuming counterfactual scenarios were extended for 12 months. Relative risks for each exposure difference were estimated with exposure-risk functions. In the Acute Period, reductions in NO2 (range of change from -16.9 mu g/m3 to -1.1 mu g/m3), noise (from -5 dB(A) to -2 dB(A)), physical activity (from -659 MET*min/wk to -183 MET*min/wk) and greenspace visits (from -20.2 h/m to 1.1 h/m) were largest in Barcelona and smallest in Stockholm. In the Deconfinement Period, NO2 (from -13.9 mu g/m3 to -3.1 mu g/m3), noise (from -3 dB(A) to -1 dB(A)), and physical activity levels (from -524 MET*min/wk to -83 MET*min/wk) remained below pre-pandemic levels in all cities. Greatest impacts were caused by physical activity reductions. If physical activity levels in Barcelona remained at Acute Period levels, increases in annual diagnoses for MI (mean: 572 (95% CI: 224, 943)), stroke (585 (6, 1156)), depression (7903 (5202, 10,936)), and anxiety (16,677 (926, 27,002)) would be anticipated. To decrease cardiovascular and mental health impacts, reductions in NO2 and noise from the first COVID-19 surge should be sustained, but without reducing physical activity. Focusing on cities' connectivity that promotes active transportation and reduces motor vehicle use assists in achieving this goal.
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| 12. |
- Liu, Zibo, 1989-, et al.
(författare)
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Broadband locally resonant metamaterial sandwich plate for improved noise insulation in the coincidence region
- 2018
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Ingår i: Composite structures. - : Elsevier. - 0263-8223 .- 1879-1085. ; 200, s. 165-172
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Tidskriftsartikel (refereegranskat)abstract
- A new design for locally resonant metamaterial sandwich plates is proposed in this paper for noise insulation engineering applications. A systematic method to tune the resonance frequency of local resonators is developed in order to overcome the coincidence phenomenon. This method, based on an impedance approach, additionally explains the ability to overcome the antiresonance associated with these local resonators. The influence of the radiated sound from these local resonators is further investigated with finite element (FE) models, particularly in connection with the sound transmission loss (STL) of the resulting metamaterial sandwich plates. The new sandwich design proposed emerges from these analyses, encapsulating the resonators inside the core material. In addition to overcoming the coincidence effect and limiting the noise radiation by the resonators, the proposed design allows to improve the mass ratio of the metamaterial sandwich structure. This, in turn, enables to broaden the working frequency band independently of the material adopted for the resonator. The proposed metamaterial sandwich plate thus combines improved acoustic insulation properties, while maintaining the lightweight nature of the sandwich plate and its good static properties.
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| 13. |
- Liu, Zibo, 1989-, et al.
(författare)
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Design of broadband acoustic metamaterials for low-frequency noise insulation
- 2017
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Ingår i: The Journal of the Acoustical Society of America. - : Acoustical Society of America (ASA). - 0001-4966. ; , s. 3574-3574
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- An innovative configuration of an acoustic sandwich structure is proposed in this paper, which uses the locally resonant structures to generate stopbands in desired frequency regions and hence to increase the sound transmission loss of the panel. Effects of different types of resonators, including the mounting techniques, are investigated. The methods to broaden the effective stopbands are discussed. The acoustic properties of the sandwich panel with non-flat laminates are also studied. Numerical analyses show that good results can be obtained when combining the laminate modification with the locally resonantstructure, especially when the stopbands are designed to compensate the corresponding coincidence effects of the sandwich panel. The analysis is based on the Finite Element models constructed in COMSOL. Bloch wave vectors are derived at first Brillouin zone by using wave expansion method. Dispersion relation of the structure is discussed. Experimental validation is planned, and the results will be shown in the conference.
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| 14. |
- Liu, Zibo, 1989-
(författare)
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Design of soundproof panels via metamaterial concept
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The goal of the work is to find a way to improve the sound insulation properties of different types of panels in order to meet different requirements. Inspired by the nontrivial behavior of the locally resonant acoustic metamaterials, this concept is introduced into the design of structures in order to explore the potential ways to improve the sound insulation behavior in the relevant specific frequency regions. At relatively low frequency region when the bending wavelength is much longer than the distance between isolated resonators, which is also the interesting frequency range in the most part of the work, it may be assumed that the effects of the resonators are uniformly distributed over the entire surface. An impedance approach is hence proposed to estimate the sound transmission loss of the metamaterial panels in order to get more insights from physics. This is realized, in general, by integrating the equivalent impedance of the resonators together with the corresponding impedance of the host panel. Valuable theories are derived based on that, laying a solid foundation for effective/efficient design of metamaterial panels. This approach also provides a fast and reliable tool for the designs prior to a time-consuming and computationally expensive numerical simulation. Based on that, a new design for locally resonant metamaterial sandwich plates is proposed to improve the sound transmission loss performance in the coincidence frequency region. A systematic method to tune the resonance frequency of local resonators is developed. This approach also supplies a method to remove the possible side-dips associated with the resonance of the resonators. The influence of the sound radiation from the resonators is further investigated with the Finite Element models. It is proposed to embed the resonators inside the core material in order to eliminate the possible influence, and also to make a smooth surface. The metamaterial sandwich panel designed in this way combines improved acoustic insulation properties with the lightweight nature of the sandwich panel. Besides the coincidence frequency region, the ring frequency area of a cylindrical shell is another important frequency region for bad sound transmission loss. The effectiveness of locally resonant metamaterial is also investigated. Similar to the case of the flat panel, both impedance model and Finite Element model are developed for the problem of the sound transmission loss properties. The influence of the resonators is presented, and compared with the case of the flat panel. Unlike the case of the metamaterial flat panel, two side-dips around the sharp improvement cannot be avoided when applying the resonators near the ring frequency of the curved panel. The reason for that is explored by using the impedance approach. It is noticed that, while the impedance of a flat panel near the critical frequency is shifted from a masstype impedance to stiffness-type impedance, the impedance of a cylindrical shell is shifted from a stiffness-type (tension-type) impedance to mass-type iv impedance. For a traditional mass-spring type resonator, however, the equivalent impedance is always shifted from a mass-type impedance to stiffness-type impedance when the frequency crosses the resonance frequency. Therefore, when the traditional resonators are applied near the ring frequency, there are always frequencies at which the impedances cancel each other, resulting in the worsened sound transmission loss. In order to have better improvement of the sound transmission loss in this frequency region, new types of resonators have to be developed. A locally resonant metamaterial curved double wall is proposed and studied, with the aim of addressing the mass-spring-mass resonance and ring frequency effects of the wall. The sound transmission loss properties of a curved double wall are first investigated by introducing the concept of ‘apparent impedance’, which expresses the properties of the entire structure in terms of the impedances of the constituting panels and air cavity. The apparent impedance derivation is validated against Finite Element models. The curved double wall is then specifically designed by adjusting the two characteristic frequencies to be close to each other in order to narrow the region associated with a poor transmission loss. This enables, subsequently, to improve the transmission loss in this region by effectively inserting tuned local resonators. The design principles are discussed, and applications for double walls consisting the same curved panels or different curved panels are both included.
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| 15. |
- Liu, Zibo, 1989-, et al.
(författare)
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Improving sound insulation near ring and coincidence frequencies of cylindrical sandwich shells
- 2022
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Ingår i: International Journal of Mechanical Sciences. - : Elsevier BV. - 0020-7403 .- 1879-2162. ; 235, s. 107661-
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Tidskriftsartikel (refereegranskat)abstract
- This paper proposes an impedance-based design methodology for cylindrical sandwich shells, with the aim to improve the sound transmission loss properties near the ring and coincidence frequency regions. The approach enables to systematically address the poor acoustic performance, characteristic of these problematic frequency regions, while retaining the mechanical properties of these structures. This is done by seeking to suppress the mass-controlled region in the frequency spectrum, with properly tuned characteristic frequencies of the structure, completed by a degree of damping treatment. The impedance-based approach allowing this tuning is derived from the canonical wave equation with a view to sound transmission through cylindrical shells. In addition to offering fast, early design possibilities, the method provides physical insights into the vibroacoustic performance of the shell, for instance introduced to estimate the sound transmission loss of shallow curved sandwich panels in the low-frequency range. Oblique-and diffuse-field conditions are investigated, validating the analytical developments against finite element calculations.
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| 16. |
- Liu, Zibo, 1989-, et al.
(författare)
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Investigation of the sound transmission through a locally resonant metamaterial cylindrical shell in the ring frequency region
- 2019
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Ingår i: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 125:11
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 17. |
- Liu, Zibo, 1989-, et al.
(författare)
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Investigation on the acoustic behaviour of a locally resonant metamaterial curved panel
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 18. |
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| 19. |
- Liu, Zibo, 1989-, et al.
(författare)
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Locally resonant metamaterial curved double wall to improve sound insulation at the ring frequency and mass-spring-mass resonance
- 2021
-
Ingår i: Mechanical systems and signal processing. - : Elsevier BV. - 0888-3270 .- 1096-1216. ; 149
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Tidskriftsartikel (refereegranskat)abstract
- A locally resonant metamaterial curved double wall is proposed and studied. The aim is to improve the sound insulation by introducing a metamaterial design targeting a narrow fre-quency band region associated with characteristic frequencies of curved double walls, thus enabling an overall improvement of sound insulation properties in a broader frequency range. This metamaterial is realized by introducing periodically distributed resonators to a curved double wall. The sound transmission loss properties of such curved double walls are first investigated by using the concept of 'apparent impedance', which expresses the properties of the whole structure in terms of the impedances of the constituting panels and air cavity. The apparent impedance approach is validated against Finite Element models. It is shown that, instead of a dip in the sound transmission loss around the ring fre-quency of a single curved panel, the curved double wall may exhibit a broad 'valley' with low sound transmission loss, whose bandwidth is determined by the spacing between the two characteristic frequencies of the structure (associated with the ring frequency and mass-spring-mass resonance of the curved double wall). The curved double wall is then specifically designed by adjusting the two characteristic frequencies to be close to each other in order to narrow the region associated with a low transmission loss. This enables, subsequently, to improve the transmission loss in this region by effectively inserting tuned local resonators. The design principles are discussed, and applications of double walls consisting either of the same curved panels or different curved panels are both included.
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| 20. |
- Lundberg, Eva, 1964-, et al.
(författare)
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Analytical method for predicting micro-geometry based flow resistivity in anisotropic foams to improve sound absorption of vehicle panels
- 2021
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Ingår i: Proceedings of the Resource Efficient Vehicles Conference - 2021 (rev2021). - Stockholm, Sweden.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Vehicle structures such as train floors or car roofs are usually built as multi-layer panels, where a foam is placed between a load-carrying structure and an interior panel. The foam adds acoustical and thermal performance, but very little weight. In most contributions introducing foams for acoustic treatment, these have been considered isotropic, with acoustic losses mainly dependingon properties in the thickness direction. Another mechanism investigated here is the possibilityfor the acoustic flow in the foam to change from acting only in the thickness direction but rather to be re-directed to also travel in-plane, where dimensions are substantially larger than in the thickness direction, permitting more losses as the wave travels through the material. That kind of effect would result in higher acoustic losses without increasing the thickness of the vehicle panel and better use of the allowable space to achieve acoustic and functional requirements, i.e. a better functional density. A first step is to investigate how the absorption properties of an anisotropic foam differs from an isotropic foam. The chosen approach is to use an analytical micro-modelto calculate the dynamic drag impedance (flow resistivity on micro-scale) for an anisotropic opencell foam material. Based on a simple micro-scale geometry of Kelvin cells, it has been shown that simple cell alterations to the micro-geometry, such as stretching, twisting and tilting results in an anisotropic foam structure. The anisotropic flow resistivity tensor is not diagonal and uniform, but different directions can have different magnitudes and it can display off-diagonal coupling terms. The influence of such micro-scale distortions on the flow resistivity, and on the resulting sound absorption is investigated with the purpose of improving the acoustic performance without adding volume. Future steps include to modify the functional density and tailor the sound transmission loss to a specific application.
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| 21. |
- Lundberg, Eva, 1964-, et al.
(författare)
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Tuning sound transmission loss for multi-layer panels with anisotropic foams
- 2022
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Ingår i: Proceedings of ISMA 2022 - International Conference on Noise and Vibration Engineering and USD 2022 - International Conference on Uncertainty in Structural Dynamics. - : KU Leuven, Departement Werktuigkunde. ; , s. 429-441
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Multilayer panels consisting of a load carrying structure, a porous material for thermal and acoustic insulation and an interior trim panel is a very common type of design for vehicles. Weight as well as total build height are usually limiting constraints on the design. The idea of using an anisotropic porous material instead of an isotropic one to improve the sound transmission loss without adding a lot of weight or thickness is explored in the paper. By using a state space formulation of the transfer matrix method transmission loss it is possible to include anisotropic material properties in the calculation. The anisotropic material is modelled by a combination of a simplified analytical model for the acoustic losses and inverse estimation of the 21 independent elastic constants of the Hooke’s tensor. The porous material, which has typical dimensions possible to 3D print, is based on a Kelvin cell micro model that has a controlled degree of anisotropy.
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| 22. |
- Mao, Huina, et al.
(författare)
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3D tunable anisotropic metamaterial for low-frequency vibration absorption
- 2021
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Ingår i: Proceeding of Resource Efficient Vehicles 2021.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In the well-known conflict between design space and performance requirements e.g. in termsof noise and vibration insulation, the emergence of new materials exhibiting exceptional insula-tion properties for a reduced weight or volume increase has received much attention in the lastdecade. Metamaterials with artificially designed architectures are increasingly considered as newfunctional materials with unusual properties. This paper presents a group of novel 3D latticemetamaterials for low-frequency vibration absorption. The novel lightweight cellular microstruc-tures for vibro-acoustic metamaterials are designed by modification of the Kelvin cell. Interestinganisotropic material properties are generated by controlling the geometries, e.g., high-stiffness,auxetic, and strong compression-torsional coupling properties. The interesting meta-propertiesenable to tune the cellular resonators of the structures at a low-frequency range. Previous researchis mostly focused on metamaterials for vibration absorption along only one or two directions. Inthis paper, wide-band high sound absorption properties of energy transfer coupling in all threedirections are achieved by tunning the frequency-dependent meta-structures in controlling the ge-ometry and material properties. Additive manufacturing technologies are used for making the 3Dcomplex tunable metamaterials.
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| 23. |
- Mao, Huina, et al.
(författare)
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A note on the linear deformations close to the boundaries of a cellular material
- 2021
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Ingår i: Mechanics research communications. - : Elsevier BV. - 0093-6413 .- 1873-3972. ; 111
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Tidskriftsartikel (refereegranskat)abstract
- Previously reported measurements of uniaxial compression of cellular acoustic materials have shown an intriguing loss of stiffness in the regions close to the boundaries. The present contribution attempts to further investigate if these effects may be modelled by assuming a local alteration of the microstructure in these regions close to the boundaries resulting from cutting a block of material into smaller samples. Assuming that fewer struts contribute locally to the mechanical behaviour, implies a reduced equivalent porosity, or relative density, in the boundary region. The approach explored here consists in randomly removing a portion of the struts constituting the microstructure of the cells because of damage incurred in the cutting process. The analysis is performed using a linear elastic deformation behaviour at the boundary of cellular acoustic materials. For the modelling of the microstructure, the Kelvin cell geometry is chosen. Applying the assumption that struts are damaged in the process of cutting a block of material into smaller samples, as an explanation for the observed high-strain boundary regions, it is shown that the experimental observations may be qualitatively reproduced. It is also shown that the equivalent density in the boundary regions may be estimated from the ratio of the boundary compressive modulus to that of the interior region of the sample. Through the presented results, the approximation errors in compression stiffness measurements performed for a real material may be estimated. Although providing a viable explanation of the experimentally observed behaviour of the boundary regions, it should be understood that the proposed approach primarily offers a simple, accurate equivalent description of this phenomenon.
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| 24. |
- Mao, Huina, et al.
(författare)
-
An inverse method for characterisation of the static elastic Hooke's tensors of solid frame of anisotropic open-cell materials
- 2020
-
Ingår i: International Journal of Engineering Science. - : Elsevier Ltd. - 0020-7225 .- 1879-2197. ; 147
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 25. |
- Mao, Huina, et al.
(författare)
-
An inverse method for design and characterisation of acoustic materials
- 2019
-
Ingår i: MATEC Web of Conferences. - : EDP Sciences. - 2261-236X.
-
Konferensbidrag (refereegranskat)abstract
- This paper presents applications of an inverse method for the design and characterisation of anisotropic elastic material properties of acoustic porous materials. Full field 3D displacements under static surface loads are used as targets in the inverse estimation to fit a material model of an equivalent solid to the measurement data. Test cases of artificial open-cell foams are used, and the accuracy of the results are verified. The method is shown to be able to successfully characterise both isotropic and anisotropic elastic material properties. The paper demonstrates a way to reduce costs by characterising material properties based on the design model without a need for manufacturing and additional experimental tests.
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| 26. |
- Mao, Huina, et al.
(författare)
-
Dynamic behaviour of low- to high-density anisotropic cellular materials
- 2022
-
Ingår i: Journal of Sound and Vibration. - : Elsevier BV. - 0022-460X .- 1095-8568. ; 536
-
Tidskriftsartikel (refereegranskat)abstract
- The dynamic behaviour of a novel anisotropic cellular micro-structural geometry derived from the basic symmetric Kelvin cell is discussed for varying relative density. The cells are arranged in a cubic array and the dynamic response is studied in a classical seismic mass setup using beam elements to represent the ligaments of the cell. The eigenfrequencies and the eigenmodes of the cellular array are computed together with forced response simulations where a proportional damping model of the Young's modulus for the cell ligaments is assumed. The frequency dependence of the damping is based on a fractional derivative representation. Using a recently developed inversion method, equivalent, homogenised solid material models of the cellular array are discussed with the associated equivalent elastic properties given in terms of the 21 elastic constants of the Hooke's tensor. For the equivalent solid material models, the eigenfrequencies and eigenmodes are computed, and forced response simulations are performed assuming the same type of proportionality in the damping as the cellular array, for the same seismic mass setup. The correlation, between the eigenfrequencies and the eigenmodes, shows an overall interesting agreement between the cellular and the equivalent solid model for the quite complex deformation shapes observed. The forced response results indicate that the equivalent solid modelling accurately represents the global dynamics of the anisotropic cellular array, but needs to be further refined when local shearing deformation within the individual cells starts to be dominating.
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| 27. |
- Mao, Huina, et al.
(författare)
-
Twist, tilt and stretch: From isometric Kelvin cells to anisotropic cellular materials
- 2020
-
Ingår i: Materials & design. - : Elsevier BV. - 0264-1275 .- 1873-4197. ; 193
-
Tidskriftsartikel (refereegranskat)abstract
- Simple geometric distortions applied to the isometric Kelvin cell structures, (the tetrakaidecahedron), are shown to result in equivalent materials with anisotropic Hooke's tensors. The equivalent material models are estimated using a recently published inversion method where the 21 independent elastic constants of the Hooke's tensor are identified. In these cell geometries, some of the faces of the Kelvin cell have been twisted and/or tilted. Numerical experiments suggest that the equivalent material models of the distorted cells exhibit variations in compression, shearing, shear-compression and shear-shear coupling moduli, which are shown to be continuous functions of the degree of twist and tilt applied. When twist and tilt are combined, it is demonstrated that full anisotropy in the elastic properties may be generated. A rotational symmetry without symmetry planes, but having either a tetragonal or a monoclinic elastic symmetry is discussed. Four cell geometries, one isometric and three distorted, were manufactured using masked stereolithography 3D printing technology and measured in a laboratory compression set-up. Results from numerical simulations are compared to the experimental in terms of the compressive modulus.
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| 28. |
- Mao, Huina, et al.
(författare)
-
Vibro-acoustic behaviour of low- to high-density anisotropic cellular foams
- 2020
-
Ingår i: PROCEEDINGS OF INTERNATIONAL CONFERENCE ON NOISE AND VIBRATION ENGINEERING (ISMA2020) / INTERNATIONAL CONFERENCE ON UNCERTAINTY IN STRUCTURAL DYNAMICS (USD2020). - : KATHOLIEKE UNIV LEUVEN, DEPT WERKTUIGKUNDE. ; , s. 451-461
-
Konferensbidrag (refereegranskat)abstract
- The paper discusses the vibro-acoustic behaviour of a recently proposed novel anisotropic cellular foam geometry derived from the basic symmetric Kelvin cell geometry. The associated equivalent elastic material properties are estimated based on a recently developed inversion method, in terms of the 21 elastic constants of the Hooke's tensor. The dynamic behaviour of the cellular material configuration and its homogeneous model by applying the equivalent material properties are studied under arbitrary excitation. The correlation between the vibro-acoustic behaviour, foam density, and material anisotropy is studied based on finite element simulations. High correlations of eigenfrequency and eigenmode shapes between the target cellular foam model and the equivalent solid model are found. A set of empirical relations are proposed, linking the micro-structure in low to high relative density for the anisotropic cellular geometries investigated. Potential applications in vibro-acoustic of the proposed anisotropic foam are discussed
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| 29. |
- Rice, H., et al.
(författare)
-
A development on fast frequency sweep methods for acoustic radiation problems
- 2016
-
Ingår i: Proceedings of ISMA 2016 - International Conference on Noise and Vibration Engineering and USD2016 - International Conference on Uncertainty in Structural Dynamics. - : KU Leuven, Departement Werktuigkunde. - 9789073802940 ; , s. 521-533
-
Konferensbidrag (refereegranskat)abstract
- The direct point by point swept solution of the discretised Helmholtz equation over a broad frequency range can become computationally expensive for large systems when fine frequency increments are required. Approaches involving reduced-order models using Padé-or waveform-based methods such as the well conditioned asymptotic waveform evaluation (WCAWE) can be used to significantly reduce this and can also be applied to systems with non-quadratic frequency dependency. In this paper WCAWE expansions are performed on a finite element based dynamical model of a two microphone open flanged impedance tube test. The use of an approximate loss-factor-based PML type approach to model the radiating section of the system is considered which eliminates dependency on reciprocal frequency terms. This allows for an efficient high order expansion as the frequency derivative terms need to be retained only up to second order. It is then shown that the method efficiently gives robust predictions of the end impedance with simple non-specialized elements.
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| 30. |
- Rumpler, Romain, 1983-, et al.
(författare)
-
A finite element solution strategy based on Padé approximants for fast multiple frequency sweeps of coupled elastic, poroelastic, and internal acoustic problems
- 2013
-
Ingår i: Journal of the Acoustical Society of America. - : Acoustical Society of America (ASA). - 0001-4966 .- 1520-8524. ; 133:5, s. 3241-3241
-
Tidskriftsartikel (refereegranskat)abstract
- Analyses involving structural-acoustic finite element models including three-dimensional modeling of porous media are, in general, computationally costly. While being the most commonly used predictive tool in the context of noise and vibrations reduction, efficient solution strategies enabling the handling of large-size multiphysics industrial problems are still lacking, particularly in the context where multiple frequency response estimations are required, e.g., for topology optimization, multiple load cases analysis, etc. In this work, an original solution strategy is presented for the solution of multi-frequency structural-acoustic problems including poroelastic damping. Based on the use of Padé approximants, very accurate interpolations of multiple frequency sweeps are performed, allowing for substantial improvements in terms of computational resources, i.e., time and memory allocation. The method is validated and demonstrated for its potential on 3D applications involving coupled elastic, poroelastic, and internal acoustic domains.
|
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| 31. |
- Rumpler, Romain, 1983-, et al.
(författare)
-
A finite element solution strategy based on Padé approximants for fast multiple frequency sweeps of multivariate problems
- 2013
-
Ingår i: Proceedings of Meetings on Acoustics. - : Acoustical Society of America (ASA). ; , s. 065003-
-
Konferensbidrag (refereegranskat)abstract
- Analyses involving structural-acoustic finite element models including three-dimensional modelling of porous media are, in general, computationally costly. While being the most commonly used predictive tool in the context of noise and vibrations reduction, efficient solution strategies enabling the handling of large-size multiphysics industrial problems are still lacking, particularly in the context where multiple frequency response estimations are required, e.g. for topology optimization, multiple load cases analysis, etc. In this work, an original solution strategy is presented for the solution of multi-frequency structural-acoustic problems including poroelastic damping. Based on the use of Padé approximants, very accurate interpolations of multiple frequency sweeps are performed, allowing for substantial improvements in terms of computational ressources, i.e. time and memory allocation. The method is validated and will be demonstrated for its potential on 3D applications involving coupled elastic, poroelastic and internal acoustic domains.
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| 32. |
- Rumpler, Romain, 1983-, et al.
(författare)
-
A multivariate WCAWE for parametric model order reduction
- 2022
-
Ingår i: Proceedings of ISMA 2022 - International Conference on Noise and Vibration Engineering and USD 2022 - International Conference on Uncertainty in Structural Dynamics. - : KU Leuven, Departement Werktuigkunde. ; , s. 2057-2070
-
Konferensbidrag (refereegranskat)abstract
- Engineering applications often depend on multiple parameters, leading to a need for increasingly complex problems to be solved by numerical methods. The use of so-called parametric reduced-order models, based on the underlying physics, has proved to be an efficient approach to address a prohibitive computational cost with increasing dimensionality of the parametric space, while offering the prospect of an accurate approximation of the original problem. In this contribution, a multivariate version of the well-conditioned asymptotic waveform evaluation (WCAWE) algorithm is presented, namely the MWCAWE, in order to extend its applicability to parametric problems. It is applied in an adaptive algorithm based on a residue-based contour following approach. This algorithm computes reduced-order models of bi-variate acoustic problems where frequency and a material parameter are considered. A poro-acoustic application is presented, highlighting the potential of the multi-interval strategy for parametric applications.
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| 33. |
- Rumpler, Romain, 1983-, et al.
(författare)
-
A multivariate, well-conditioned asymptotic waveform evaluation for finite element solutions with complex parametric dependence
- 2018
-
Ingår i: Proceedings of ISMA 2018 - International Conference on Noise and Vibration Engineering and USD 2018 - International Conference on Uncertainty in Structural Dynamics.
-
Konferensbidrag (refereegranskat)abstract
- 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 poroelastic and internal acoustic domains.
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| 34. |
|
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| 35. |
- Rumpler, Romain, 1983-, et al.
(författare)
-
Comparison of the component-wise and projection-based Padé approximant methods for acoustic coupled problems
- 2017
-
Ingår i: Journal of the Acoustical Society of America. - : Acoustical Society of America (ASA). - 0001-4966 .- 1520-8524. ; 141:5, s. 4033-4033
-
Tidskriftsartikel (refereegranskat)abstract
- Several Padé-based computational methods have been recently combined with the finite element method for the efficient solution of complex time-harmonic acoustic problems. Among these, the component-wise approach, which focuses on the fast-frequency sweep of individual degrees of freedom in the problem, is an alternative to the projection-based approaches. While the former approach allows for piecewise analytical expressions of the solution for targeted degrees of freedom, the projection-based approaches may offer a wider range of convergence. In this work, the two approaches are compared for a range of problems varying in complexity, size and physics. This includes for instance the modeling of coupled problems with non-trivial frequency dependence such as for the modeling of sound absorbing porous materials. Conclusions will be drawn in terms of computational time, accuracy, memory allocation, implementation, and suitability of the methods for specific problems of interest.
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| 36. |
- Rumpler, Romain, 1983-
(författare)
-
Efficient Finite Element Approach for Structural-Acoustic Applications including 3D modelling of Sound Absorbing Porous Materials
- 2012
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the context of interior noise reduction, the present work aims at proposing Finite Element (FE) solution strategies for interior structural-acoustic applications including 3D modelling of homogeneous and isotropic poroelastic materials, under timeharmonic excitations, and in the low frequency range. A model based on the Biot-Allard theory is used for the poroelastic materials, which is known to be very costly in terms of computational resources. Reduced models offer the possibility to enhance the resolution of such complex problems. However, their applicability to porous materials remained to be demonstrated.First, this thesis presents FE resolutions of poro-elasto-acoustic coupled problems using modal-based approaches both for the acoustic and porous domains. The original modal approach proposed for porous media, together with a dedicated mode selection and truncation procedure, are validated on 1D to 3D applications.In a second part, modal-reduced models are combined with a Padé approximants reconstruction scheme in order to further improve the efficiency.A concluding chapter presents a comparison and a combination of the proposed methods on a 3D academic application, showing promising performances. Conclusions are then drawn to provide indications for future research and tests to be conducted in order to further enhance the methodologies proposed in this thesis.
|
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| 37. |
- Rumpler, Romain, 1983-, et al.
(författare)
-
Fast frequency sweeps for unbounded media : An efficient perfectly matched layer finite element formulation
- 2020
-
Ingår i: EURODYN 2020: XI International Conference on Structural Dynamics. ; , s. 2508-2520
-
Konferensbidrag (refereegranskat)abstract
- Effective treatment of unbounded domains using artificial truncating boundaries are essential in numerical simulation including unbounded media, such as in the scope of exterior acoustics, sound transmission calculations,... Among these, Perfectly Matched Layers (PML) have proved to be particularly efficient and flexible, as well as relatively easy to implement using the Finite Element Method (FEM). However, an efficient handling of frequency sweeps is not trivial with such absorbing layers since the formulation inherently contains coupled space- and frequency-dependent terms. Using the FEM, this may imply generating system matrices at each step of the frequency sweep. In this contribution, an approximation is presented in order to allow for efficient frequency sweeps, for instance using Pade-based methods as extensively used by the authors in previous contributions. The performance and robustness of the proposed approximation is presented on an acoustic cases. A generic, robust way to truncate the acoustic domain efficiently is also proposed, tested on a range of test cases and for different frequency regions. It is shown that the approximation, based on a sub-interval approximation of a tuning parameter in the frequency range of interest, provides consistently very good results, close to the costly, original formulations. An a priori estimate of a robust choice for this tuning parameter is also introduced, together with a set of empirical recommendations associated with mesh size, domain size and truncation.
|
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| 38. |
- Rumpler, Romain, 1983-, et al.
(författare)
-
MULTIVARIATE PADÉ APPROXIMANTS FOR FINITE ELEMENT SOLUTIONS WITH COMPLEX PARAMETRIC DEPENDENCE
- 2019
-
Konferensbidrag (refereegranskat)abstract
- 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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| 39. |
- Rumpler, Romain, 1983-, et al.
(författare)
-
MWCAWE: A multivariate WCAWE approach for parametric model order reduction, and a sampling strategy for the bivariate case
- 2023
-
Ingår i: Journal of Computational Physics. - : Elsevier BV. - 0021-9991 .- 1090-2716. ; 490, s. 112319-
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, the multivariate well-conditioned asymptotic waveform evaluation (MWCAWE) algorithm is presented. It is based on a univariate version of the algorithm, previously introduced for fast frequency sweeps. Taking advantage of the robustness of this univariate algorithm, the MWCAWE enables to effectively generate multi-parameter reduced-order models. Additionally, a residue-based contour following approach is introduced for a two-stage generation of a projection basis, here applied on bi-variate acoustic problems where frequency and a material parameter are in focus. The effectiveness of the proposed method is demonstrated on two poro-acoustic problems, highlighting both the good convergence property of the algorithm and the potential of the multi-patch strategy for parametric applications.
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| 40. |
- Rumpler, Romain, 1983-, et al.
(författare)
-
Noise measurements as a proxy to evaluating the response to recommendations in times of crisis : An update analysis of the transition to the second wave of the CoViD-19 pandemic in Central Stockholm, Sweden
- 2021
-
Ingår i: Journal of the Acoustical Society of America. - : Acoustical Society of America (ASA). - 0001-4966 .- 1520-8524. ; 149:3, s. 1838-1842
-
Tidskriftsartikel (refereegranskat)abstract
- Sweden stands out among the other European countries by the degree of restrictive measures taken towards handling the 2019 coronavirus outbreak, associated with the CoViD-19 pandemic. While several governments have imposed a nationwide total or partial lockdown to slow down the spread of the virus, the Swedish government has opted for a recommendation-based approach together with a few imposed restrictions. In a previous contribution by the authors, the impact of the Swedish strategy was observed through the monitored variation of the city noise levels during a period associated with the so-called "first wave" of the pandemic in Stockholm. A very strong impact of these recommendations was shown on the evolution of the noise levels in central Stockholm. This highlighted the potential of acoustic sensor networks both for enforcement of regulation and monitoring of the effectiveness of their implementation. The present contribution presents a follow-up to this urban noise monitoring in central Stockholm, Sweden, for the period leading to the so-called "second wave" of the pandemic in Europe. Both the evolution of adherence to the recommendations and the impact of the recurrence of cases combined with reinforced recommendations are observed through the evolution of the measured noise levels. While the measurements show a gradual lower level of compliance, in particular, past the summer break, these also show again a rapid response to the reinforced recommendations issued by the authorities in mid-fall of 2020. These observations thus confirm the potential associated with detailed urban noise monitoring, for instance here acting as a proxy to evaluating the response to recommendations or restrictions in times of crisis.
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| 41. |
|
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| 42. |
- Rumpler, Romain, 1983-
(författare)
-
Padé Approximants For Multivariate Reduced Order Models
- 2020
-
Ingår i: 3rd Euro-Mediterranean Conference on Structural Dynamics and Vibroacoustics, 17-19 February 2020, Naples, Italy.
-
Konferensbidrag (refereegranskat)abstract
- 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 poroelastic and internal acoustic domains.
|
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| 43. |
- Venkataraman, Siddharth, 1994-, et al.
(författare)
-
ACOUSTIC STUDY OF NIGHTTIME DELIVERIES IN STOCKHOLM WITHIN THE PROJECT CIVITAS ECCENTRIC
- 2020
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The present contribution reports part of the study conducted in the context of the CIVITAS ECCENTRIC European project, focused on the investigation of the conditions for silent deliveries in the city of Stockholm, Sweden.In particular, the methodology and results associated with measurements performed in 2019 are presented, in order to evaluate the impact of a potential increase of deliveries during sensitive nighttime segments.Two aspects of noise emissions are considered: traffic noise and delivery noise, measured both from a truck driving on a delivery route to 6 locations and a façade at one of the delivery locations.A plug-in hybrid electric vehicle (PHEV) is used, together with the application of a geofencing strategy associated with densely populated urban areas, in order to evaluate potential solutions addressing driving noise emissions.Concerning delivery noise emissions, critical in the context of nighttime deliveries, the relative impact associated with a range of different configurations at the delivery locations chosen is evaluated.Both the configuration at the delivery location (road-pavement transitions, surface type) and the time segment of delivery are found to be critical factors contributing to the overall impact of delivery noise.
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| 44. |
- Venkataraman, Siddharth, et al.
(författare)
-
An approach to improve railway rolling noise calculations in CNOSSOS-EU: Refinement and validation using TWINS calculations
- 2021
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The reliability of CNOSSOS-EU methodology for evaluation of railway noise is dependent on the quality ofinput values that define the system’s excitation and transfer functions. Currently available input values are limited and of insufficient quality, resulting in large errors in noise level calculations. A case study wherein railway rolling noise mitigation measures are evaluated with both CNOSSOS-EU and TWINS show deviations in resulting sound power levels of up to 8 dB(A) and 4 dB(A) for absolute and relative measures respectively. An approach to process TWINS output to extract transfer functions as input values for CNOSSOS-EU is described in this paper. The updated CNOSSOS-EU calculations correspond well with those of TWINS, with the maximum deviation limited to 1.5 dB(A) and 1 dB(A), respectively, for the same absolute and relative measures.
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| 45. |
- Venkataraman, Siddharth, et al.
(författare)
-
Improving strategic noise mapping of railway noise in Europe : Refining CNOSSOS-EU calculations using TWINS
- 2022
-
Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 839, s. 156216-
-
Tidskriftsartikel (refereegranskat)abstract
- The Environmental Noise Directive (2002/49/EC) requires all European Union Member States to produce strategic noise maps using a common assessment methodology: CNOSSOS-EU. The reliability of CNOSSOS-EU railway noise evaluation is dependent on the input vehicle and track transfer functions. The CNOSSOS-EU default database contains the currently available choices for these transfer functions. However, these available transfer functions are limited and of insufficient quality, resulting in large errors in noise level calculations. An approach is presented, introducing an established analytical railway rolling noise calculation technique (TWINS), to extract more reliable and specific transfer functions. A case study consisting of railway rolling noise mitigation measures is defined and used as the basis for extracting and testing these transfer functions. The extracted transfer functions reduce the average deviation between CNOSSOS-EU and reference calculations using TWINS from6.1 dB(A) to 0.8 dB(A) in absolute sound power levels, and from 1.2 db(A) to 0.3 dB(A) in estimates of noise reduction potential for the defined mitigation measures. Application of this approach shows potential to improve the quality and depth of the existing CNOSSOS-EU default database. This may lead to more reliable estimations of railway noise in the strategic noise maps and the subsequent assessment of its harmful effects.
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| 46. |
- Venkataraman, Siddharth, et al.
(författare)
-
Models for vehicle detection from noise measurements in sparse road traffic
- 2023
-
Ingår i: Forum Acusticum 2023 - 10th Convention of the European Acoustics Association, EAA 2023. - : European Acoustics Association, EAA.
-
Konferensbidrag (refereegranskat)abstract
- Road traffic noise calculations require modeling the traffic flow in a road network. The reliability of these calculations can be improved with accurate estimation of the traffic flow, including estimation of its temporal variations. Low-cost noise sensors that run on single-board computers in a noise monitoring network are suitable candidates to simultaneously estimate the local temporal traffic flow from their pass-by measurements, using an on-board traffic flow estimator model. Aside from this model requiring to be computationally efficient, it should also be robust, e.g., invariant to sensor position relative to the source, weather conditions, etc. With noise measurements as an input, different noise features and prediction models are tested for vehicle detection. The accuracy of these models is evaluated using traffic count data obtained from dedicated vehicle-counting infrastructure at the locations of the noise sensors. The analysis is restricted to sparse traffic conditions in this initial study.
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| 47. |
- Venkataraman, Siddharth, et al.
(författare)
-
Optimizing noise exposure in the Vehicle Routing Problem : A case study of last-mile freight deliveries in Stockholm
- 2022
-
Ingår i: Internoise 2022. - : The Institute of Noise Control Engineering of the USA, Inc..
-
Konferensbidrag (refereegranskat)abstract
- Improvements in noise mapping techniques and smart cities infrastructure have fostered the development of new ways to evaluate traffic noise exposure. An example of one such outcome is the noise exposure sensitivity map, which quantifies the noise exposure potential of a road network as a function of the vehicle type, the prevailing background noise, and the population exposed. The potential for planning vehicle routing that is offered by the above-mentioned map calls for solving the Vehicle Routing Problem (VRP) with a focus on optimising the noise exposure. A case study is chosen for applying the VRP, and it is taken from last-mile off-peak deliveries performed in Stockholm, Sweden in the context of the CIVITAS Eccentric project. The VRP is independently solved for the following objectives: distance travelled, driving time, and driving noise exposure potential. Also considered is a heterogeneous objective that is a combination of these factors. The impact of the objective function, on the resulting routes is presented.
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| 48. |
- Weber, Franziska, et al.
(författare)
-
Numerical investigation of periodic metamaterials
- 2020
-
Ingår i: Proceedings ISMA 2020 International Conference on Noise and Vibration Engineering, 2020. ; , s. 2441-2449
-
Konferensbidrag (refereegranskat)abstract
- Various contributions have shown that periodic structures with specific material composition or geometry layout have favorable dispersion characteristics. A special feature of so called metamaterials is the occurrence of stop bands, being frequency ranges where no free wave propagation is observed. The focus of this contribution lies on two dimensional metamaterials with periodic inclusions and notches. Using the Wave Finite Element Method the dispersion characteristics of periodic metamaterials can be studied on the basis of a Finite Element Model of one repetitive segment (unit cell). The periodicity of the structure is introduced by applying Bloch’s Theorem. The scope of this contribution is to investigate the influence of the topology and shape of inclusions and notches on the wave propagation in periodic metamaterials. In continuation of a former publication by the authors a wide-ranging parameter study analyzes the relation between the variance in mass distribution along the unit cell and the stop band behavior.
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| 49. |
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