| 1. |
- Dazel, O., et al.
(författare)
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An efficient solver for finite-element poroelastic problems
- 2012
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Ingår i: Proceedings - European Conference on Noise Control. - 9788001050132 ; , s. 851-853
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Konferensbidrag (refereegranskat)abstract
- Structural-acoustic finite element models including 3D modelling of poroelastic media modelled with the Biot theory are generally computationally costly. While being the most commonly used predictive tool in the context of noise reduction applications, efficient solution strategies are required. In this work, an original modal reduction technique, involving real-valued decoupled modes computed from a classical eigenvalue solver is proposed to reduce the size of the problem associated to the porous media. The idea of this technique is to enhance the modal basis with static correction calculated analytically which account for the response of non-preserved modes.
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| 2. |
- Gaborit, Mathieu, et al.
(författare)
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Influence of uncertain parameters on the acoustic behaviour of sound proofing laminates
- 2019
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Ingår i: INTER-NOISE 2019 MADRID - 48th International Congress and Exhibition on Noise Control Engineering. - : SOCIEDAD ESPANOLA DE ACUSTICA - Spanish Acoustical Society, SEA.
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Konferensbidrag (refereegranskat)abstract
- The protection against excessive noise has gathered a lot of attention along the years. Tailored solutions for specific types of noise conditions emerged and many communications on the subject are published every year. Although designing sound proofing systems is a well developed topic, building the proposed systems is still subject to many uncertainties. For instance, the very nature of the foams used in many broadband absorbers implies a degree of uncertainty on some of the most important parameters (e.g. the airflow resistivity). This phenomenon is even more noticeable in modern sound absorbing laminates in which every interface implies a barely controllable change in the continuity conditions. This effect being rarely accounted for and the interfaces' properties hard to quantify, it adds uncertainties that are widely neglected even though having a potentially strong impact. In this contribution, the effect of randomly distributed parameters on the overall acoustic response of multi-layer systems is considered. The influence of choosing specific acoustic models for each layer is emphasized and the resulting response envelope is studied.
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| 3. |
- Gaborit, Mathieu Maël, et al.
(författare)
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Coupling FEM, bloch waves and TMM in meta poroelastic laminates
- 2018
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Ingår i: Acta Acoustica united with Acustica. - : S. Hirzel Verlag GmbH. - 1610-1928 .- 1861-9959. ; 104:2, s. 220-227
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Tidskriftsartikel (refereegranskat)abstract
- The propagation of airborne plane waves in the presence of a meta poroelastic laminate, that is a poroelastic matrix coated with thin elastic layers at its facings and periodically-embedded with inclusions, is studied. Using the Finite Element Method (FEM) only would result in a drastic increase of the degrees of freedom due to the fine mesh required to account for the very thin coatings. Here, the approach relies on: The Bloch wave expansion of the fields in air; the modal Transfer Matrix Method to account for the coatings; and the coupling with the FEM model of the poroelastic matrix and the resonant inclusions. The model is developed for reflection and transmission problems and it can account for coatings with multiple layers. The procedure induces the addition of the Bloch coefficients in the FEM's linear system at a negligible additional computational cost. It is applied to the meta poroelastic laminates with poroelastic inclusions and rubber shell inclusions. The results are compared with those from the Multiple Scattering Theory and an excellent agreement between the methods is found. The approach offers a numerically-efficient way to account for coatings applied to meta poroelastic layers, and finds applications in industrial prototypes where coatings are widely used.
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| 4. |
- Gaborit, Mathieu, et al.
(författare)
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Off-line envelope estimation for acoustic screens with uncertain properties
- 2019
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Ingår i: Proceedings of the International Congress on Acoustics. - : International Commission for Acoustics (ICA). - 9783939296157 ; , s. 1992-1999
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Konferensbidrag (refereegranskat)abstract
- The development of new solutions to reduce impact of noise receives constant attention both from the research and engineering communities. Even though the proposed systems tend to diversify, multi-layered absorbers based on foams remain the most common. Such structures feature one or several thick slabs of foam and are completed by protective or tuning layers of small thickness inserted between slabs or on the free surface. These layers (acoustics screens or films) bring a number of challenges. Firstly, their thickness makes them hard to characterise and some parameters are uncertain. Secondly, the bonding to the surrounding system alter the effective properties. Given the strong influence the films have on the system's response, it appears important to account for these uncertainties from the design phase on. The present contribution introduces a new technique to efficiently account for uncertainty linked to the screens. More precisely, the proposed approach is based on separating the average film influence from the deviation due to uncertainties. This allows to estimate the response envelope using a pre-computed average response and the properties. The results computed for a range of typical and challenging configurations are promising and validate the robustness of the method at any angle of incidence.
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