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Modelling strategies for thin imperfect interfaces and layers

Time: Fri 2019-12-13 10.15

Location: F3, Lindstedtsvägen 26, Stockholm (English)

Subject area: Engineering Mechanics

Doctoral student: Mathieu Gaborit , MWL Marcus Wallenberg Laboratoriet, LAUM UMR CNRS 6613, Le Mans Université, Le Mans, France

Opponent: Lucie Rouleau, Laboratoire de Mécanique des Structures et des Systèmes Couplés, Conservatoire national des arts et métiers, Paris, France

Supervisor: Peter Göransson, MWL Marcus Wallenberg Laboratoriet, Farkostteknik, VinnExcellence Center for ECO2 Vehicle design; Olivier Dazel, LAUM UMR CNRS 6613, Le Mans Université, Le Mans, France

Abstract

The global trend towards quieter environments has been one of the key topics of acoustics research for years. The recent tightening of the regulations on noise exposure as well as the many reports on the impact of noise on human health confirm this situation and stress ever more the need for innovative mitigation strategies. Numerous efforts from many teams allowed to refine existing solutions and explore new approaches towards a lower noise level ultimately leading to a number of promising concepts. Central to this field, the use of poroelastic media and the development of realistic meta-materials are paving the way to tackle the problem. In the meantime, a great part of the most widely adopted systems to mitigate noise, such as acoustics panels for instance, resort to thin resistive screens placed on the surface to protect the bulk and control the properties. Despite often being one of the thinnest components of the systems, they have a non-negligible impact on the overall response and are subject to a number of uncertainties.The approach chosen in this thesis differs from the global trend of designing new solutions and conversely relies on investigating the effect of uncertainties inherent to all these sound proofing systems. More precisely, the work performed focuses on modelling the impact of uncertain interfaces and uncertain parameters in the thin layers used as protective, tuning or aesthetic elements. These acoustic films, and to a certain extent the thin interface zones resulting from the assembly process, are notably challenging to characterise with precision. The main goal of this thesis is then to propose strategies to account for uncertainties on the parameters of the films and interfaces and predict their impact on the overall response of the systems.Three different scientific contributions are presented in this thesis. Together they discuss modelling aspects related to the films, propose possible simplifications and demonstrate the effect of parameter uncertainties. Finally they introduce numerical strategies to efficiently account for uncertainties in computations within the context of poroelastic and meta-poroelastic media.

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Last changed: Nov 19, 2019