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Title: Determination of damage severity on rotor shaft due to crack using damage index derived from experimental modal data

Abstract

After long duration of an operation, a shaft under high spin speeds and heavy loadings may develop fatigue cracks. This could lead to catastrophic failure and could be difficult to detect. An accurate prediction of dynamic characteristics of rotor system is fundamentally important. Hence, a practical method to nondestructively locate and estimate the severity of a crack in terms of its damage index by measuring the changes in natural frequencies of the rotor shaft is presented. In this study, experimental modal analysis (EMA) data were utilized. A crack detection algorithm to locate and identify cracks in the rotor system using the first and second natural frequencies was outlined. Subsequently, a crack-locating model was formulated by relating the fractional changes in modal energy to the changes in natural frequencies as a result of cracks based on the experimentally obtained natural frequencies and mode shapes’ functions. The feasibility and practicality of the crack detection scheme were evaluated for several damage scenarios by locating and sizing cracks in test rotor shafts for which the first two natural frequencies were available. It was observed that crack could be confidently located with a relatively small localization error. It was also observed that crack severity couldmore » be estimated in terms of its damage index.« less

Authors:
 [1];  [2];  [3]
  1. University of Malaya, Mechanical Engineering Department, Faculty of Engineering (Malaysia)
  2. University Malaysia Pahang, Faculty of Mechanical Engineering (Malaysia)
  3. University of Malaya, Civil Engineering Department, Faculty of Engineering (Malaysia)
Publication Date:
OSTI Identifier:
22771694
Resource Type:
Journal Article
Journal Name:
Experimental Techniques
Additional Journal Information:
Journal Volume: 38; Journal Issue: 5; Other Information: Copyright (c) 2014 Society for Experimental Mechanics, Inc.; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0732-8818
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; ALGORITHMS; CRACKS; DAMAGE; DETECTION; ERRORS; FAILURES; FATIGUE; FORECASTING; ROTORS; SHAPE; SIZE; VELOCITY

Citation Formats

Ong, Z. C., E-mail: zhichao83@gmail.com, Rahman, A. G. A., and Ismail, Z. Determination of damage severity on rotor shaft due to crack using damage index derived from experimental modal data. United States: N. p., 2014. Web. doi:10.1111/J.1747-1567.2012.00823.X.
Ong, Z. C., E-mail: zhichao83@gmail.com, Rahman, A. G. A., & Ismail, Z. Determination of damage severity on rotor shaft due to crack using damage index derived from experimental modal data. United States. doi:10.1111/J.1747-1567.2012.00823.X.
Ong, Z. C., E-mail: zhichao83@gmail.com, Rahman, A. G. A., and Ismail, Z. Mon . "Determination of damage severity on rotor shaft due to crack using damage index derived from experimental modal data". United States. doi:10.1111/J.1747-1567.2012.00823.X.
@article{osti_22771694,
title = {Determination of damage severity on rotor shaft due to crack using damage index derived from experimental modal data},
author = {Ong, Z. C., E-mail: zhichao83@gmail.com and Rahman, A. G. A. and Ismail, Z.},
abstractNote = {After long duration of an operation, a shaft under high spin speeds and heavy loadings may develop fatigue cracks. This could lead to catastrophic failure and could be difficult to detect. An accurate prediction of dynamic characteristics of rotor system is fundamentally important. Hence, a practical method to nondestructively locate and estimate the severity of a crack in terms of its damage index by measuring the changes in natural frequencies of the rotor shaft is presented. In this study, experimental modal analysis (EMA) data were utilized. A crack detection algorithm to locate and identify cracks in the rotor system using the first and second natural frequencies was outlined. Subsequently, a crack-locating model was formulated by relating the fractional changes in modal energy to the changes in natural frequencies as a result of cracks based on the experimentally obtained natural frequencies and mode shapes’ functions. The feasibility and practicality of the crack detection scheme were evaluated for several damage scenarios by locating and sizing cracks in test rotor shafts for which the first two natural frequencies were available. It was observed that crack could be confidently located with a relatively small localization error. It was also observed that crack severity could be estimated in terms of its damage index.},
doi = {10.1111/J.1747-1567.2012.00823.X},
journal = {Experimental Techniques},
issn = {0732-8818},
number = 5,
volume = 38,
place = {United States},
year = {2014},
month = {9}
}