Virtual method for modeling of multilayer noise absorbers

MSc Thesis proposal at Volvo Group (30 ECTS, two students):
Virtual method for modeling of multilayer noise absorbers
The Master of Science Thesis work will be performed at the Volvo Group Trucks Technology, which is responsible for product development within the Volvo Group.
Noise is an important emission in the society today and one part of the work for a better environment is to lower the radiated noise from vehicles. This is done in several ways and one important is to encapsulate the noise sources with sound absorbing material. In the development process, the first design steps are done in Finite Element Method (FEM) software (SW) environment by modelling the products. To get accurate results from these studies, the input data has to be as relevant as possible.
Today complex surface impedance is used to represent absorption in finite element models used for engine encapsulation absorption materials. With such method, noise encapsulation shields back face is considered as fully reflective and there is no possibility to assess transmission through the encapsulation. The existing method does not either allow to extrapolate absorption for materials with different compression rate.
For the proposed thesis work, the aim is to:
  • Build up knowledge around numerical simulation of acoustic porous material used for engine encapsulation. Focus on how to handle multilayers and different compression grades
  • Investigate the noise transmission through the materials and how to handle the transmission in models using FEM SW
The basis for the thesis work will be extended material data for a typical engine encapsulation material and the work will be to model the data in a FEM SW and verify the model by measurements.
The work program will include:
  • Implementation & validation of the FE model using impedance data for sound absorption
  • Comparison of impedance data representation & full Biot element for sound absorption
  • Comparison of several approaches for sound transmission
  • Sensitivity study regarding input parameters
  • Feasibility study for representing compressed materials for sound absorption and sound transmission
The outcome from the thesis work will be:
  • Verified numerical models of extracted material data
  • Correlation study between physical tests and numerical models to assess absorption
  • Correlation study between physical tests and numerical models to assess transmission
  • Sensitivity analysis in order to determine the level of precision required for the input data for numerical models of porous material
Your profile:
  • Master student at an Acoustical program
  • Knowledge in Finite Element Methods and FEM SW
Sophie Girolami, Volvo Group (Volvo responsible for the numerical implementation of the models)
PhD François-Xavier Bécot, Matelys (Matelys responsible for the characterization and modeling)
Pr Wolfgang Kropp, Applied Acoustics, Chalmers (Chalmers responsible for the empirical analysis)
Contact person:
Krister Fredriksson, Volvo Group, +46 31 3221535


The Volvo Group is one of the world’s leading manufacturers of trucks, buses, construction equipment and marine and industrial engines under the leading brands Volvo, Renault Trucks, Mack, UD Trucks, Eicher, SDLG, Terex Trucks, Prevost, Nova Bus, UD Bus and Volvo Penta.

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