Title page for ETD etd-08032002-124724

Type of Document Master's Thesis
Author Davis, Ivan Christopher
Author's Email Address idavis@vt.edu
URN etd-08032002-124724
Title Damage Detection in Aluminum Cylinders Using Modal Analysis
Degree Master of Science
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Wicks, Alfred L. Committee Chair
Duma, Stefan M. Committee Co-Chair
Garnett, Charles Committee Member
  • Mechanical Engineering
  • Damage Detection
  • Modal Analysis
  • Statistics
Date of Defense 2002-07-31
Availability unrestricted
Many studies have attempted to detect structural damage by examining differences in the frequency response functions of a structure before and after damage. In an experimental setting, this variation can not be attributed solely to the addition of damage. Other sources of variation include testing and structure variation. Examples of testing variation include the error introduced by modal parameter extraction, measurement noise, and the mass loading of the accelerometer. Structure variability is due to slight differences in the supposedly identical structures. Dimensional tolerancing is one example.

This study began with six "identical" undamaged aluminum cylinders, of which three were later damaged to varying extents. The frequency response functions of the undamaged and damaged cylinders were measured. Also, the frequency response function of the same undamaged cylinder was measured multiple times to investigate testing variation. The contributions of testing, cylinder, and damage variation to the differences between cylinder responses was elucidated by specifically examining their frequency response functions in two ways: comparing the natural frequencies and directly investigating the entire frequency response function. The curvature of the frequency response functions was then used to determined the presence, location, and severity of the imparted damage.

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