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2004 년도 대한토목학회 학술발표회

2004 년도 대한토목학회 학술발표회. Experimental Comparison of Structural Damage Detection Methods. 임현우 , 한국과학기술원 건설및환경공학과 석사과정 문영종 , 한국과학기술원 건설및환경공학과 박사과정 이종헌 , 경일대학교 토목환경공학과 교수 이인원 , 한국과학기술원 건설 및 환경공학과 교수. Introduction.

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2004 년도 대한토목학회 학술발표회

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  1. 2004년도 대한토목학회 학술발표회 Experimental Comparison of Structural Damage Detection Methods 임현우, 한국과학기술원 건설및환경공학과 석사과정 문영종, 한국과학기술원 건설및환경공학과 박사과정 이종헌, 경일대학교 토목환경공학과 교수 이인원, 한국과학기술원 건설 및 환경공학과 교수

  2. Introduction • Damage detection becomes a very important issue and, there are a lot of evaluation methods in this field. • Experimental investigation was planed for comparison of some of these various methods. • Aluminum cantilever beams are used for comparison of time, frequency domain and mode shape method. • Experiment is focused on the applicability of the three methods in practical situations. Structural Dynamics & Vibration Control Lab., KAIST, Korea

  3. 0.4cm 4cm 60cm aluminum beam • Experimental setup • Equipment • - FFT analyzer ( B&K ) • - impact hammer ( PCB ) • - accelerometer ( B&K ) • - shaker ( YAVETEX ) • Damage case • - size (%) : 5, 10, 20, 30 • - location : 1/4, 2/4, 3/4 Structural Dynamics & Vibration Control Lab., KAIST, Korea

  4. Frequency domain method • Comparison of natural freq. • - measured freq : 1st,2nd,3rd • - damage case : 10, 20, 30% • : 1/4, 2/4, 3/4 Differences in 1st natural freq. Differences in 2nd natural freq. Differences in 3rd natural freq. Structural Dynamics & Vibration Control Lab., KAIST, Korea

  5. FRF based method - where, : undamaged FRF : damaged FRF Damage size 30%, location 1/4 Damage size 30%, location 2/4 Damage size 30%, location 3/4 Structural Dynamics & Vibration Control Lab., KAIST, Korea

  6. Mode shape method • Comparison of mode shape • - measured mode shape : 2nd • - damage case : 10, 20, 30% • : 1/4, 2/4, 3/4 Damage location 1/4 Damage location 2/4 Damage location 3/4 Structural Dynamics & Vibration Control Lab., KAIST, Korea

  7. Wavelet transform • Simulation ( FEM ) • - dimension (cm) : 60×4×0.4 • - no. of element : 240 • - element type : beam Finite element model by MIDAS • Damage • - size (%) : 10, 20, 30 • - location : 1/4, 2/4, 3/4 • - element no. : 60, 120, 180 Damage size 30%, location 2/4 Structural Dynamics & Vibration Control Lab., KAIST, Korea

  8. Mode Shape (MS) • where, : Undamaged mode shape vector • : Damaged mode shape vector • Mode Shape Slope (MSS) • Mode Shape Curvature (MSC) & (MSCS) • , Structural Dynamics & Vibration Control Lab., KAIST, Korea

  9. Simulation : damage case 20%, 1/4 Structural Dynamics & Vibration Control Lab., KAIST, Korea

  10. Time domain method • Wave propagation • - impact at fixed end : 9.8 ms • - 1st arrival at free end : 10.3ms • - reflection from damages : - • - 2nd arrival at free end : 11.1ms Undamaged Damage size 30%, location 1/4 Damage size 30%, location 2/4 Structural Dynamics & Vibration Control Lab., KAIST, Korea

  11. Effect of experimental errors Structural Dynamics & Vibration Control Lab., KAIST, Korea

  12. Conclusions • Under 10% damages can be found by various detection methods with simulation, however it is impossible by experiment because of practical problems. • Not exact location of damages but existence of them can be detected by frequency domain method. • Simulation of mode shape method find even small damages, however its experimental result is insufficient to detect damages. • Time domain method can find the location of relatively large damages. Structural Dynamics & Vibration Control Lab., KAIST, Korea

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