Table of Contents Author Guidelines Submit a Manuscript
International Journal of Rotating Machinery
Volume 7 (2001), Issue 2, Pages 105-115

Instantaneous Purified Orbit: A New Tool for Analysis of Nonstationary Vibration of Rotor System

1Research Institute of Vibration Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
2Research Institute of Diagnostics and Cybernetics, Xian Jiaotong University, Xian 710049, China

Received 15 June 1999; Revised 8 October 1999

Copyright © 2001 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


In some circumstances, vibration signals of large rotating machinery possess time-varying characteristics to some extent. Traditional diagnosis methods, such as FFT spectrum and orbit diagram, are confronted with a huge challenge to deal with this problem. This work aims at studying the four intrinsic drawbacks of conventional vibration signal processing method and instantaneous purified orbit (IPO) on the basis of improved Fourier spectrum (IFS) to analyze nonstationary vibration. On account of integration, the benefits of short period Fourier transform (SPFT) and regular holospectrum, this method can intuitively reflect vibration characteristics of’a rotor system by means of parameter analysis for corresponding frequency ellipses. Practical examples, such as transient vibration in run-up stages and bistable condition of rotor show that IPO is a powerful tool for diagnosis and analysis of the vibration behavior of rotor systems.