PhD Defense - Fadi KARKAFI

Nonstationary vibration diagnostics of rotating machinery: application to aeronautic power transmission systems

The proper functioning of rotating machines relies on vibration monitoring of fragile rotating components such as gears and bearings. Concerning more particularly the case of power transmission systems in aeronautics, vibration monitoring presents considerable challenges that are addressed in this thesis: (i) nonstationary operating regimes, which require the adoption of synchronous approaches, (ii) complex interactions between different subsystems, likely to mask or disturb diagnostic signals and (iii) noise emitted by various sources, both environmental and internal, making fault detection more difficult. To address these challenges, the diagnostic principles proposed in this thesis are structured around several objectives: (1) a reliable estimation of the instantaneous angular speed, allowing the synchronization of the signals with the variations of the regime, (2) the extraction of the relevant vibration components to isolate the critical mechanical components and (3) the application of specific diagnostics to each component, taking into account the operational variations to guarantee robustness and reliability. The developed methodologies are validated by experimental data, demonstrating their potential to improve the reliability and safety of transmission systems in aeronautics.

Membres du jury :
- Marie Chabert (Rapporteuse)
- Karim Abed Meraim (Rapporteur)
- Demba Diallo (Examinateur)
- Cédric Peeters (Examinateur)
- Quentin Leclère (Directeur de thèse)
- Jérôme Antoni (Co-directeur de thèse)
- Mohammed El Badaoui (Co-encadrant de thèse)
- Dany Abboud (Invité)
- Konstantinos Gryllias (Invité)