Khaoutar AOUALI : "Quasiperiodic arrays of weakly coupled nonlinear oscillators for vibration energy harvesting by electromagnetic or electromagnetic-piezoelectric transductions"

Abstract : A study on nonlinear electromagnetic and hybrid oscillator arrays for vibration energy harvesting is conducted in this thesis. The common harvesters’ limitations namely the narrow bandwidth and the low amount of the harvested energy are overcome by investigating different enhancement approaches. First, the energy localization phenomenon was functionnalized in a 2-DOFs with electromagnetic transduction system. It has been shown that it permits minimizing the number and the cost of electrical circuits and therefore the technological constraints of the structure. After that, the combination of nonlinear dynamics with the mode localization phenomenon has been studied. It has been proven that nonlinear dynamics allow a robustness of the mode localization phenomenon. Add to that, this combination permits improving the harvested power up to 19 % and the frequency of the bandwidth up to 116% and ensures an enhancement up to 101% and 79% in terms of harvested power and frequency bandwidth in the case of quasiperiodic 5-DOFs device. Moreover, in order to further improve the total harvested power, the electromagnetic system was transformed into hybrid one by adding piezoelectric layers. The internal resonance phenomenon is, also, investigated for the hybrid electromagnetic piezoelectric structure. Well-chosen gaps between the magnets result in activating the 2:1 internal resonance and a significant improvement of the hybrid harvester output performance has been demonstrated. It has been shown that it is possible to reduce the harvester’s volume by nearly two times while increasing the frequency bandwidth and the harvested power by 300% and 100% respectively comparing to a nonlinear harvester away from internal resonance.

Jury Composition :

M. Noureddine BOUHADDI Professeure des universités Université Bourgogne Franche-Comté PhD Director
M. Mohamed-Najib ICHCHOU Professeur des universités Ecole Centrale de Lyon Reporter
M. Mnaouar CHOUCHANE Professeur des universités Ecole Nationale d'Ingénieurs de Monastir Reporter
M. Skandar BASROUR Professeur des universités Université Grenoble-Alpes Reviewer
M. Fakhreddine DAMMAK Professeur des universités Ecole Nationale d'Ingénieurs de Sfax Reviexer
M. Mohamed HADDAR Professeur des universités Ecole Nationale d'Ingénieurs de Sfax PhD Co-director
M. Najib KACEM Maîtresse de conférences Université Bourgogne Franche-Comté PhD Co-supervisor

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