| 11. |
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| 12. |
- Brunskog, Jonas, et al.
(författare)
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Prediction model for the impact sound level of lightweight floors
- 2003
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Ingår i: Acta Acustica united with Acustica. - 1436-7947. ; 89:2, s. 309-322
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Tidskriftsartikel (refereegranskat)abstract
- Lightweight floors are often troubled by poor impact-sound insulation. In order to develop and explain structures with acceptable insulation, a deterministic prediction model was developed. The paper considers transmission through the system and the response of the model. Excitation (as caused by the ISO-tapping machine) is considered in a separate paper [1]. The system description employs a spatial transform technique, making use of the periodicity of the floor structure with the aid of Poisson's sum rule. The radiated power is calculated using numerical integration in the wave-number domain, the radiated power enabling the impact sound level to be calculated. Comparisons are made between measurements found in the literature and the proposed prediction model, the effects of different excitation models being discussed. A relatively close agreement is achieved, especially if an elaborate excitation model is employed.
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| 13. |
- Brunskog, Jonas, et al.
(författare)
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Rigid indenter excitation of plates
- 2003
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Ingår i: Acta Acustica united with Acustica. - 1436-7947. ; 89:3, s. 460-470
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Tidskriftsartikel (refereegranskat)abstract
- The paper presents expressions for the point mobility of infinite plates driven by a completely rigid indenter. The problem is of general interest in connection with the excitation and transmission of structure-borne sound. The indenter is assumed to be circular, weightless, and stiff compared with the plate. A rigid indenter is assumed to provide a better approximation of the actual situation than a soft indenter would, e.g when a hammer acts on a wooden plate. A detailed three-dimensional analysis is performed. Traditionally, the problem is solved in approximate terms by assuming a pressure distribution at the interface between the indenter and the plate. In the present study, a pressure distribution is also assumed, an optimal choice of the pressure amplitude being found by means of a variational formulation. Numerical results are presented and discussed, the discrepancy between the results obtained and the perfectly rigid indenter being examined.
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| 14. |
- Brunskog, Jonas, et al.
(författare)
-
Sound transmission between infinite rooms; a modal approach and fe-formulation
- 2003
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Ingår i: Proceedings of the 10th International Congress on Sound and Vibration. ; , s. 4541-4548
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Konferensbidrag (refereegranskat)abstract
- A full description of the entire system room-wall-room in a theoretical model for sound insulation is still today too computation intensive, implying that the higher frequencies cannot be studied. Some simplifications must thus be introduced. The simplification proposed in the present paper is to replace the rooms with wave-guides, i.e. infinity long rooms. The model then reduces to the (more or less) two-dimensional wall. The question of how to apply the excitation then arises. The choice herein is to use a combination of diffuse field and Monte Carlo simulations. The incident and radiated power, expressed in the wave-guide modes, is used to calculate the transmission loss. A minor literature survey is also included.
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| 15. |
- Brunskog, Jonas, et al.
(författare)
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Sound transmission of structures. A finite element approach with simplified room description
- 2004
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Ingår i: Acta Acustica united with Acustica. - 1861-9959. ; 90:5, s. 847-857
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Tidskriftsartikel (refereegranskat)abstract
- A theoretical prediction model for the sound insulation of a wall is an important tool when developing new wall structures. A full description of the entire room-wall-room system in a theoretical model for sound insulation is still today too computation-intensive, implying that the sound insulation at higher frequencies cannot be studied. Some simplifications must thus be introduced. The simplification proposed in this present paper is to describe the rooms with waveguides, i.e., infinity-long rooms. The model then reduces to the (more or less) two-dimensional wall. The question of how to apply the excitation then arises. The choice proposed here is to use a combination of diffuse field and Monte Carlo simulations. The incident and radiated power, expressed in waveguide modes, are used to calculate the transmission loss. A minor literature survey is also included, as well as numerical results and comparison with experimental results. The method presented is developed to study the sound insulation of lightweight double-leaf walls, and the numerical results of such walls are presented.
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| 16. |
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| 17. |
- Brunskog, Jonas, et al.
(författare)
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The interaction between the ISO tapping machine and lightweight floors
- 2003
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Ingår i: Acta Acustica united with Acustica. - 1436-7947. ; 89:2, s. 296-308
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Tidskriftsartikel (refereegranskat)abstract
- The ISO standard tapping machine, used as an excitation source in rating the impact-sound level of a floor structure, interacts with the floor structure during the hammer impact. Expressions for the force spectrum due to the impact are presented. The 6 dB difference at low frequencies of the force spectrum, evident in measurements, and reasons for it, are discussed. The interaction is investigated by use both of simplified lumped models and arbitrary frequency-dependent models. Local effects due to indentation near the point of impact and to global effects due to stiffeners are included in the description of the mobility involved. Numerical results are presented, where it is concluded that both the local and the global effects of the driving-point mobility are important in describing the force spectrum caused by the interaction between the tapping machine and the complex floor structure.
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| 18. |
- Brunskog, Jonas
(författare)
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Wave-modes of a double-plate system with joists and cavity
- 2003
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Ingår i: Proceedings of the 10th International Congress on Sound and Vibration. ; , s. 4555-4562
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Konferensbidrag (refereegranskat)abstract
- Lightweight walls and floors are often designed as frameworks of studs with plates on each side - a double-plate structure. The free wave-modes and periodic wave motion of a double-plate system reinforced by joists are analysed in the present paper (as the insertion loss and impact sound insulation have been studied in previous papers). The free wave-modes can in a future step be used in connection with flanking transmission. The cavity between the plates is assumed locally reacting. A spatial transform technique is used, making use of the periodicity.
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| 19. |
- Davidsson, Peter, et al.
(författare)
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Analysis of sound transmission loss of double-leaf walls in the low-frequency range using the finite element method
- 2004
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Ingår i: Building Acoustics. - : SAGE Publications. - 1351-010X .- 2059-8025. ; 11:4, s. 239-257
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Tidskriftsartikel (refereegranskat)abstract
- The sound transmission loss of double walls in the low-frequency range is studied by means of structure-acoustic finite element analysis. The analysis simulates standard experiments to determine sound transmission loss of walls. The model is a detailed description of the geometry of the system, including both the double wall and the rooms acoustically coupled to the wall. The frequency range studied is in the 1/3-octave bands between 40 Hz and 200 Hz. A parametric study is performed to investigate the influence on the sound transmission loss of various material and geometric properties of the wall and the dimensions of the connecting rooms. The model confirms the importance of primary structural resonance and the size of the connecting rooms in determining the degree of sound transmission loss. The primary structural resonance is mainly determined by the distance between the wall studs and the properties of the sheeting material. Wall length is also important; if the length is such that the wall studs of the last wall cavity are closer together than those of the other wall cavities, the primary structural resonance will be at a higher frequency, thereby decreasing sound transmission loss over a broader frequency range. Similar dimensions of the connecting rooms results in poor transmission loss, mainly at frequencies below 100 Hz (for the wall and room dimensions studied here).
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| 20. |
- Davidsson, Peter, et al.
(författare)
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Sound reduction in double walls at low frequencies - A parametric study
- 2003
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Ingår i: Proceedings of the 10th International Congress on Sound and Vibration. ; , s. 4601-4608
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Konferensbidrag (refereegranskat)abstract
- The sound transmission in double walls at low frequencies is studied using a detailed geometric model, based on FEM. The model simulates the experiments carried out to determine the sound reduction index of the wall. The wall properties effect on the sound transmission loss is investigated and also how the sound reduction is affected by the dimensions of the connecting rooms.
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