Athanasios Theodoridis, MPNAT Nanotechnology, presenterar sitt examensarbete med titeln "Characterization of Graphene based porous structures for noise damping in transmission systems"
Handledare: Dr. Yifeng Fu (Chalmers), Dr. Flavio Presezniak (Volvo AB)
Opponent: Awse S. A. Salha
Examinator: Prof. Johan Liu
Abstrakt: Noise pollution is an environmental issue that has been gaining more and more attention over the last years. Heavy machinery such as trucks are a big contributor to this problem, and stricter environmental regulations drive companies into finding better solutions where they can keep noise levels to a minimum, while still being profitable. Recently developed porous graphene films (PGFs) can be a promising solution, since they are thin, lightweight and industrially produced. Due to their film structure and inherent porosity, in the form of air pockets, they are studied, for the first time, for their potential to be incorporated into today's acoustic applications. In this project, PGFs are investigated in terms of their thermal, structural and acoustical properties. For the first two, several characterization methods are employed, namely a self-heating method, the buoyancy method, tensile stress measurements, BET analysis and SEM imaging, among others. For the latter impedance tube measurements are conducted, in order to investigate the acoustic performance and characterize the PGFs in terms of their acoustic properties. For that matter, both measurements on sample acoustic devices and simulations are employed. Thin membrane-type acoustic devices are designed and fabricated where they exhibit absorption peaks in the low-frequency range and are compared with today's standard acoustic materials that are used in the automotive industry. Additionally, acoustical characterization leads to the estimation of certain material parameters, which are then used in the JCA model to simulate different device configurations. Simulations have shown, that in applications consisting of PU/fabric structures, the substitution of the thin fabric with a graphene film, can improve the sound absorption performance and also shift the absorption peak to lower frequencies. Finally, the recyclability of waste PGFs is investigated, in which graphene film pieces are crushed and shear exfoliated into graphene powder. This graphene powder can later be incorporated into various applications.
Fasrummet, meeting room, Kemivägen 9, MC2-huset