An Induced Shaft Deflection for Rotating Shaft Crack Detection

Abstract

Over the years various techniques have been developed to extract information on the dynamic state of the rotating machinery. This paper introduces a new method based on the phase data of the shaft rotation angle. Usually the phase data is omitted and only the frequency components of the vibration spectrum are taken into consideration. However, the transverse shaft crack has a specific angular location about the shaft axis. Therefore, it is supposed that by measuring the vibration response of the rotor deflected by an additional constant force applied perpendicularly to the shaft axis at different angular locations, different vibration signatures can be obtained. Such signatures can then be used to detect the crack. The method utilizes also the coupling phenomenon between the lateral/torsional vibrations of the cracked rotor, since the shaft is additionally excited by an external harmonic torque. The computer simulation study is based on the uncracked and cracked rotor models obtained by using the finite element (FE) approach. The results of the numerical analysis demonstrate the potential of the suggested method for the effective shaft crack detection.