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FRF Distortion Caused by Exponential Window Function on Impact Hammer Testing and Its Solution

지수창함수를 사용한 임팩트햄머 실험에서 주파수응답함수의 왜곡과 개선책

  • 안세진 (부산대학교 대학원 기계설계공학과) ;
  • 정의봉 (부산대학교 대학원 기계공학부)
  • Published : 2003.05.01

Abstract

Exponential window function Is widely used In impact hammer testing to reduce leakage error as well as to get a good S/N ratio. The larger its decaying rate is, the more effectively the leakage errors are reduced. But if the decay rate of the exponential window is too large, the FRF is distorted. And the modal parameters of the system can not be exactly identified by modal analysis technique. Therefore, it is a difficult problem to determine proper decay rate in impact hammer testing. In this paper, amount of the FRF distortion caused by exponential window is theoretically uncovered. A new circle fitting method is also proposed so that the modal parameters are directly extracted from impulse response spectrum distorted by the exponential-windowed impulse response data. The results by the conventional and proposed circle fitting method are compared through a numerical example.

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