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eXtended Finite Elements for thin acoustic layers

is planned to start in september or october 2019
PhD position
3 years

Project description

Resistive films are essential components for damping acoustic systems (acoustic layers for buildings and cars).Event if these components are of negligible volume, they are usually difficult to model with classical simulationtools as they lead to distorted meshes that are also tedious to setup.The objective of this thesis is to develop an efficient and robust numerical method in order to solve suchproblems with minimal human know-how. To achieve this objective, two main issues must be tackled :(i)On the modelling side, the behaviour of the films will be condensed across their mean surfaces, so that thereal geometry (whose thickness is negligible) does not have to be considered. This will require the developmentof a surface model formulated with jumps across the mean surface. The expertise of the LAUM laboratory(thesis M.Gaborit with KTH university) will be fundamental for this task.(ii)On the numerical side, the equations that govern the problem are numerically difficult to solve in a robustmanner with the finite element method not only due to mesh distorsions, but also due to so called pollutioneffects that degrade the solution with increasing frequency. This pollution issue can be efficiently mitigated bythe use of plane wave enrichments (discontinuous Galerkin, partition of unity) or by an increase of the order ofthe finite element approximation (p-fem). Unfortunately, geometrical issues are not solved by these approaches.These difficulties will be overcome by the use of a high-order version of the X-FEM which is currently developedat the GeM institute in the solid mechanics context.Finally, this new approach can be validated against experimental datas available at the LAUM laboratory

PDF document descriptif_these_ED_SPI.pdf — PDF document, 129 KB
Olivier Dazel