| 1. |
- Brunskog, Jonas
(författare)
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A wave approach to structural transmission loss in periodic structures: Thin beam case
- 2005
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Ingår i: Acta Acustica united with Acustica. - 1861-9959. ; 91:1, s. 91-102
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Tidskriftsartikel (refereegranskat)abstract
- When new building systems are developed, these are often lightweight constructions with a periodical set of stiffeners, developed for use in load-bearing structures and dwellings. One of the main drawbacks of this type of building systems is the sound insulation, where flanking transmission is an important issue. A prediction model for flanking transmission of lightweight building structures is thus under development. This paper is a theoretical study of the structural transmission coefficient of a junction, using a propagating wave approach. Free waves travel in the periodic wave-medium. The periodic resilient elements consist of rotation and displacement springs. The free waves meet a discontinuity (or junction), and the power transmitted through the discontinuity is then studied. The discontinuity consists of a mechanical coupling and point mass load. The model is analytic and deterministic, and makes use of a spatial Fourier transform wave approach for periodic structures. The approach is intended for flanking transmission of lightweight building structures, but it is also applicable for structures such as ships and aircraft. Numerical results are presented and discussed. It is concluded that the periodic nature of the wave media affects the power transmitted through a discontinuity.
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| 2. |
- Brunskog, Jonas
(författare)
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Image solution for clamped finite beams
- 2005
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Ingår i: Journal of Sound and Vibration. - : Elsevier BV. - 0022-460X. ; 287:4-5, s. 1057-1064
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Tidskriftsartikel (refereegranskat)abstract
- An image solution for the forced response of a clamped finite beam is developed. The finite beam is replaced by an infinite beam under spatially periodic excitation and periodic support reactions. The response is then found by a Fourier transform approach, making use of the periodicity. An explicit expression is found, using the Poisson sum formula. The aim is to describe the potential of using the image method for clamped structural acoustic and vibration problems.
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| 3. |
- Brunskog, Jonas
(författare)
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The influence of finite cavities on the sound insulation of double-plate structures
- 2005
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Ingår i: Journal of the Acoustical Society of America. - : Acoustical Society of America (ASA). - 1520-8524 .- 0001-4966. ; 117:6, s. 3727-3739
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Tidskriftsartikel (refereegranskat)abstract
- Lightweight walls are often designed as frameworks of studs with plates on each side-a double-plate structure. The studs constitute boundaries for the cavities, thereby both affecting the sound transmission directly by short-circuiting the plates, and indirectly by disturbing the sound field between the plates. The paper presents a deterministic prediction model for airborne sound insulation including both effects of the studs. A spatial transform technique is used, taking advantage of the periodicity. The acoustic field inside the cavities is expanded by means of cosine-series. The transmission coefficient (angle-dependent and diffuse) and transmission loss are studied. Numerical examples are presented and comparisons with measurement are performed. The result indicates that a reasonably good agreement between theory and measurement can be achieved.
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| 4. |
- Mosharrof, Mohammad Sazzad, et al.
(författare)
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Prediction model for the impact sound pressure level of decoupled lightweight floors
- 2009
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Ingår i: 38th International Congress and Exposition on Noise Control Engineering 2009. - Red Hook, NY : Curran Associates, Inc.. - 9781615676903 ; , s. 2038-2046
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Konferensbidrag (refereegranskat)abstract
- Prediction of impact sound insulation in timber buildings is difficult since the constructions are complex, non isotropic and show large variances. There are earlier publications on precise models of simplified structures and simplified models of complex structures, where so far, none is considered as an acceptable simplified engineering model tool. The goal of our research is to develop methodology for such a simplified engineering tool. The starting focus is to model impact sound in a simple floor model of two plates that are realistically coupled via beams. The floor structure in Nordic countries is mostly decoupled, meaning there is either no structural connection or an elastic connection between the plates and the beams. In this paper, an improved floor model is proposed where as a first step there is no physical connection between the plates and beams, and where each plate is stiffened by separate beams. Hence the construction becomes more realistic as only coupling between the plates via air trapped inside the cavity is taken into account. Next step will be to introduce resilient coupling between the respective beams. The modelling show promising results with reasonable sound insulation improvements.
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| 5. |
- Sjökvist, Lars-Göran, et al.
(författare)
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Modal Analysis for Floors in Lightweight Buildings
- 2007
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Ingår i: 36th International Congress and Exhibition on Noise Control Engineering (INTER-NOISE 2007 ISTANBUL). - : Curran Associates.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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