A review on machinery diagnostics and prognostics implementing condition-based maintenance

Artificial intelligence for fault diagnosis of rotating machinery: A review

Vibration of cracked structures: A state of the art review

Recent advances in time–frequency analysis methods for machinery fault diagnosis: A review with application examples

Residual life predictions for ball bearings based on self-organizing map and back propagation neural network methods

High speed rotating machinery operating with higher load capacity in extreme working conditions can induce fatigue crack into the systems. To avoid failure of the system, it has to be monitored continuously for cracks before it becomes critical. There is a need for the newer techniques that can detect even small cracks. The aim of the present work is to identify the crack in a rotor-bearing system using the concept of operational deflection shape and using kurtosis of vibration response. In the literature kurtosis is used for identifying bearing and gearbox defects. Higher kurtosis means more of the variance is due to infrequent extreme deviations, as opposed to frequent modestly sized deviations. In this study kurtosis deviation curve and amplitude deviation curves are also used for shaft crack detection. It has been noted that the kurtosis changes are significant when the crack is closer to the bearing locations. Single cracks and two cracks have been identified. The rotational laser vibrometer has been...

Crack detection in a rotor by operational deflection shape and kurtosis using laser vibrometer measurements

Rotordynamic characterization of rotating labyrinth gas turbine seals with radial growth: Combined centrifugal and thermal effects

Crack detection and monitoring in a rotor supported on fluid film bearings: start-up vs run-down

Leakage characteristics, influenced by centrifugal and thermal radial growth are determined computationally for a generic rotating labyrinth seal used in the gas turbine secondary air system. Three seal locations, namely, R25, R50 and R75 are represented by means of varying the rotor radius mimicking different radial positions of the seal from the shaft axis. The combined influence of seal location and its radial (Centrifugal and thermal) growth on the leakage performance is investigated for a wide-ranging speeds from 1000 to 3000 rad/s, temperatures ranging from 200 to 450 °C and pressure ratios varying from 1.1 to 2.5, for a chosen initial clearance of 500 micron. A comparison of the effect of rotation and temperature gradient among different rotors shows that the radial growth and leakage flow rates significantly vary with the increasing radius.

Influence of combined radial location and growth on the leakage performance of a rotating labyrinth gas turbine seal

The shaft misalignment, even being a common fault in rotating machinery, is not sufficiently studied. The present work addresses effects of misalignment in rotating machinery. An attempt to give a theoretical model for a rotor-coupling-bearing system has been done. The rotor-bearing system including the flexible coupling is modelled using the finite elements. The reaction forces and moments developed due to flexible coupling misalignment both for parallel and angular are derived and introduced in the model. Vibration analyses such as eigen value analysis and unbalance response are carried out for the rotor system with misaligned shafts.Copyright © 1996 by ASME

A. S. Sekhar

Papers

Crack detection in a rotor by operational deflection shape and kurtosis using laser vibrometer measurements

Rotordynamic characterization of rotating labyrinth gas turbine seals with radial growth: Combined centrifugal and thermal effects

Crack detection and monitoring in a rotor supported on fluid film bearings: start-up vs run-down

Influence of combined radial location and growth on the leakage performance of a rotating labyrinth gas turbine seal

Vibration Analysis of Rotor - Coupling - Bearing System With Misaligned Shafts