Crack Detection in a Rotor Dynamic System by Vibration Monitoring


Vibration monitoring is one of the most important techniques which are used to detect the cracks or defects in rotating mechanical systems. To distinguish characteristics of the system response that may lead to the transverse crack in rotating shaft, local asymmetry crack model is used where crack simulated by increasing the flexibility of the shaft and transverse crack in the shaft is introduced. The obtained results showed a decreasing in the resonance shaft speed with increasing the crack depth ratio. The feature is used for diagnostics the crack in the shaft by using the graphed results between the natural frequency and shaft speed. The method of detecting was applied for several crack depth ratios (uncracked, %10, %20 and %30) in a clamped-free rotor. Also for investigating the effect of position of crack and effect of mass location, a crack and mass with different locations are introduced in the shaft. Although, the presence of a transverse shaft crack has also been shown to induce an unstable response for some shaft speeds and the behavior of the 2x harmonic component of the system response is effective target observation for a monitoring system.