Vibration Signal Analysis Techniques

The program was initiated to investigate the many means of using vibration signals to detect the condition of mechanical components, with particular emphasis on gears and bearings in the helicopter power train. An exhaustive literature search was performed in which specific techniques were identified. Several visits were made to people active in the vibration diagnostics field. The techniques which were identified as being potentially useful were investigated in detail. The results of this investigation include a presentation of the state of the art of each technique and an analysis via actual helicopter data, test rig data, and a dynamic model simulation. The techniques have been broken down by mathematical function, i.e., time domain and frequency domain, and also by the components being monitored, i.e., gears or bearings. Both mechanically related and pattern recognition techniques are discussed. An extensive reference listing and a listing of companies and agencies active in diagnostics work are included.