Model Based Fault Diagnosis of a Rotor System for Unbalance, Misalignment and Crack

Abstract

Vibration in rotating machinery is mostly caused by unbalance, misalignment, shaft crack, mechanical looseness and other malfunctions. The objective of this research is to propose a model based fault diagnosis of a rotor system for unbalance, misalignment and crack. The modeling of the rotor-bearing system has been done using finite element method. In industrial rotor-bearing system unbalance, misalignment and shaft cracks are common and major sources of vibration. Presence of these faults changes the dynamic behavior of the system. These changes are taken into account by equivalent loads acting on the healthy system model. Equivalent loads on the system generate a dynamic behavior identical to that of the real faulty system. Numerical analysis was carried out for rotor- coupling-bearing system with aforementioned faults using finite element method for flexural vibrations. Numerical findings show the effect of faults in the rotor system. In order to validate the numerical results experiment were carried out with a machinery fault simulator which had provision to introduce different types of faults in a rotor system. Good agreement between the experimental results and numerical simulations has been observed.