테이퍼 캔틸레버 원형강관 균열보의 모드특성 추정 = Modal Property Estimation of Tapered Cantilever Pipe-type Cracked Beam

국문 초록 (Abstract)

본 연구에서는 테이퍼 보에 대한 미분방정식의 일반해에 캔틸레버 보의 경계조건을 적용하여 모드특성을 추정한다. 또한, 휨을 받는 테이퍼 원형강관 캔틸레버 보에 발생하는 관통균열을 모델링하기 위하여 에너지 방법을 이용하여 균열보에 대한 보 길이방향 휨강성을 구한 후 이를 이용하여 테이퍼 원형강관 캔틸레버 균열보에 대한 고유주파수와 모드형상을 추정한다. 보 길이에 따른 균열보의 휨강성 변화는 기존 연구에서 밝혀진 현상과 유사하게 합리적인 양상을 보였으며, 유도한 휨강성을 적용하여 산정한 균열보의 고유주파수는 균열 크기가 증가할수록 감소함을 확인하였고, 모드형상은 균열발생에 의해 변화함을 알 수 있었다. 연구결과는 향후 테이퍼 원형강관 캔틸레버 보 형태의 타워 구조물에 대한 진동기반 균열탐지에 활용될 수 있을 것으로 판단된다.

다국어 초록 (Multilingual Abstract)

Modal properties for tapered cantilever pipe-type beam is identified by applying the boundary conditions to a general solution for tapered beam. A bending stiffness for cracked beam is constructed based on an energy method for tapered cantilever thin-walled pipe, which has a through-the-thickness crack, subjected to bending. Then the natural frequencies and mode shapes of a tapered cantilever thin-walled cracked pipe are identified. It can be found that the phenomenon of the bending stiffness distribution along the beam length of the cracked beam is quite reasonable, the natural frequencies are decreased as the crack sizes are increased, and the mode shapes are changed due to the crack. This results may be used to the vibration-based crack identification for the tapered cantilever pipe-type tower structures.

참고문헌 (Reference)

1 Auciello, N. M., "Vibrations of a Cantilever Tapered Beam with Varying Section Properties and Carrying a Mass at the Free End" 214 : 105-119, 1998

2 Ece, M. C., "Vibration of a Variable Cross-Section Beam" 34 : 78-84, 2007

3 Tada, H., "The Stress Analysis of Cracks Handbook"

4 Chen, D. W., "The Exact Solutions for the Natural Frequencies and Mode Shapes of Non-Uniform Beams with Multiple Spring-Mass Systems" 255 : 299-322, 2002

5 Sinha, J. K., "Simplified Models for the Location of Cracks in Beam Structures using Measured Vibration Data" 251 : 13-38, 2002

6 Kemppainen, M., "Realistic Cracks for In-Service Inspection Qualification Mock-Ups" 8 : 1-8, 2003

7 National Transportation Safety Board, "Pipeline Accident Brief (DCA99-MP005), NTSB/PAB -01/01"

8 Christides, S., "One-dimensional Theory of Cracked Bernoulli-Euler Beams" 26 : 639-648, 1984

9 Naniwadekar, M. R., "On Prediction of Crack in Different Orientations in Pipe using Frequency Based Approach" 22 : 693-708, 2008

10 Murigendrappa, S.M., "Frequency-Based Experimental and Theoretical Identification of Multiple Cracks in Straight Pipes Filled with Fluid" 37 : 431-438, 2004

11 Rosa, M. A. D., "Free Vibration of Elastically Restrained Cantilever Tapered Beams with Concentrated Viscous Damping and Mass" 37 : 261-264, 2010

12 Gorman, D.J., "Free Vibration Analysis of Beams and Shafts" John Wiley & Sons 365-368, 1975

13 Franco, R. J., "Failure Analysis and Prevention, Vol. 11, ASM Handbook"

14 Dilena, M., "Detecting Cracks in Pipes Filled with Fluid from Changes in Natural Frequencies" 25 : 3186-3197, 2011

15 Wang, Y. M., "Daubechies Wavelet Finite Element Method and Genetic Algorithm for Detection of Pipe Crack" 26 : 87-99, 2011

16 Huh, Y.C, "Crack Identification of Euler-Bernoulli Beam Using the Strain Energy Method" The Korean Society for Noise and Vibration Engineering 396-400, 2006

17 Yang, X. F., "Crack Identification in Vibrating Beams using the Energy Method" 244 : 339-357, 2001