Journal of the Korean Society for Aeronautical & Space Sciences (한국항공우주학회지)

The Korean Society for Aeronautical and Space Sciences (한국항공우주학회)
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Study of Effects of Measurement Errors in Damage Detection

동적 측정오차가 손상탐지에 미치는 영향에 관한 연구

  • 김기욱 (인하대학교 공과대학 항공우주공학)
  • Received : 2010.11.03
  • Accepted : 2011.01.26
  • Published : 2011.03.01
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Abstract

A modal method is presented for the investigation of the effects of measurement errors in damage detection for dynamic structural systems. The structural modifications to the baseline system result in the response changes of the perturbed structure, which are measured to determine a unique system in the inverse problem of damage detection. If the numerical modal data are exact, mathematical programming techniques can be applied to obtain the accurate structural changes. In practice, however, the associated measurement errors are unavoidable, to some extent, and cause significant deviations from the correct perturbed system because of the intrinsic instability of eigenvalue problem. Hence, a self-equilibrating inverse system is allowed to drift in the close neighborhood of the measured data. A numerical example shows that iterative procedures can be used to search for the damaged structural elements. A small set of selected degrees of freedom is employed for practical applicability and computational efficiency.

동적구조의 손상탐지에 적용되는 모드법에서 측정오차가 계산과정의 수렴특성에 미치는 영향을 조사하였다. 구조요소의 손상과 같은 구조적 변화가 발생하면 응답특성도 변화되므로, 고유진동수 또는 고유벡터의 변화를 측정하면 구조적 변화를 밝혀낼 수 있다. 시험을 통하여 얻은 측정자료가 정확한 경우 수학적 프로그래밍은 우수한 수렴특성을 보여주고 있다. 그러나 실제 측정치는 오차를 포함하며, 고유치문제의 수치적 불안정성 때문에 작은 수치오차는 실제와 전혀 다른 계산결과를 초래할 수 있다. 그러므로 응답특성은 일정한 범위 안에서 스스로 평형상태를 찾아갈 수 있도록 허용되어야 한다. 유한요소모델에 포함되는 모든 자유도에 측정센서를 부착할 수 없으므로, 가장 효과적인 소수의 자유도를 선정하여 측정자료를 얻을 수 있으며 측정된 자유도에 대한 평형방정식을 적용한다.

Keywords

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