Thèse de doctorat : Génie mécanique : Villeurbanne, INSA : 2002. / Titre provenant de l'écran-titre. Bibliogr. p.90-95.

Thèse doctorat : Génie Electrique : Villeurbanne, INSA : 2006. / Titre provenant de l'écran-titre. Bibliogr. p. 150-155. Publications de l'auteur p. 148-149.

Thèse de doctorat : sciences. Génie Mécanique : Ecully, Ecole centrale de Lyon : 2006. / 153 réf.

Thèse de doctorat : sciences. Génie Mécanique : Ecully, Ecole centrale de Lyon : 2006. / Titre provenant de l'écran-titre. 153 réf.

Thèse de doctorat : Acoustique : Villeurbanne, INSA : 1996. / Titre provenant de l'écran-titre. Bibliogr. p.217-225.

Significant interior noise and vibrations in aircraft cabins are generated by the turbulent flow over the fuselage. The turbulent boundary layer (TBL) excitation is the most important noise source for jet powered aircraft during cruise flight. Reduced levels of interior noise are desirable both for comfort and health reasons. However, to efficiently design noise control systems, and to design new and optimized structures that are more efficient in the noise reduction, a clearer understanding of the sound radiation and transmission mechanisms is crucial. This task is far from being straightforward, mainly due to the complexity of the system consisted by the aircraft fuselage, and all the sound transmission mechanisms involved in a such complex environment. The present work aims to give a contribution for the understanding of these mechanisms. For that, a coupled aero-vibro-acoustic analytical model for the prediction of the TBL-induced noise and vibration in aircraft is developed. Closed form analytical expressions are obtained to predict the structural vibration levels, noise radiated from the structure and interior sound pressure levels. / Graduate

The work presented in this thesis is motivated by a need for an advanced understanding of the governing mechanisms for vibrations in complex structures. In order to obtain a simplified description of the complex structure with the dominant information of the structure enhanced, one removes some unimportant structural information from the description by identifying secondary contributing substructures and couplings, then describing them using simplified models. It is found that the secondary substructures are those substructures being required for their vibrational transmission characteristics only, and the secondary couplings are the weak couplings in the structure. Moreover, it is demonstrated that the transmission characteristics can be sufficiently described by using only the direct wave and the fIrst reflection in the structure, and the secondary coupling can be simplified as an idealised coupling. The procedure for establishing such a simplifIed description for the complex structure is illustrated by a two-element built-up structure. Finally, the efficiency of using such a simplifIed description to analyse the complex structure is demonstrated for two mechanical artefacts, one being a laboratory structure consisting of a cylindrical shell attached to a plate via two beams, and the other a full-scale aircraft - Eurofighter 2000.

No description available.

The demand for portable permanent sources of electrical energy increases every day to power portable or non-accessible devices. Energy harvesting from vibrations offers a non-traditional source of energy. It is renewable and prevailing, since nature around is rich in kinetic energy that can be harvested. In this work, we have developed two mechanisms to harvest energy from low-frequency vibrations present in nature using electromagnetic transduction. The harvesting mechanisms use a mass-on-spring mechanical oscillator to capture kinetic energy from a host body. Prototypes embodying the two harvesting mechanisms were fabricated and tested. We identi ed the system parameters of the harvester prototypes and generated their frequency-response curves. We analyzed the results using and compared them with mathematical models of the system dynamics to characterize the harvesters' performance including their output power, center frequency, and harvesting bandwidth. We were successful in demonstrating energy harvesters that can harvest low-frequency vibration with center frequencies in the range of 8-14 Hz, harvesting bandwidth in the range of 8-12Hz, and output power on the order of 1mW. The realized harvesters are relatively small, a few inches in dimension, and light, a few tens of grams in mass. We also introduced a novel electromagnetic transduction mechanism that can be used in harvesting low-frequency vibrations.

No description available.