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Structural Engineering and Mechanics
  Volume 35, Number 6, August20 2010, pages 773-789
DOI: http://dx.doi.org/10.12989/sem.2010.35.6.773
 


Time domain identification of multiple cracks in a beam
Z.Y. He and Z.R. Lu

 
Abstract
    It is well known that the analytical vibration characteristic of a cracked beam depends largely on the crack model. In the forward analysis, an improved and simplified approach in modeling discrete open cracks in beams is presented. The effective length of the crack zone on both sides of a crack with stiffness reduction is formulated in terms of the crack depth. Both free and forced vibrations of cracked beams are studied in this paper and the results from the proposed modified crack model and other existing models are compared. The modified crack model gives very accurate predictions in the modal frequencies and time responses of the beams particularly with overlaps in the effective lengths with reduced stiffness. In the inverse analysis, the response sensitivity with respect to damage parameters (the location and depth of crack, etc.) is derived. And the dynamic response sensitivity is used to update the damage parameters. The identified results from both numerical simulations and experiment work illustrate the effectiveness of the proposed method.
 
Key Words
    multiple cracks; dynamic response; crack identification; inverse problem.
 
Address
Z.Y. He: School of Civil and Transportation Engineering, South China University of Technology, Guangzhou 510641, P.R. China
Z.R. Lu: School of Engineering, Sun Yat-sen University, Guangzhou 510275, P.R. China
 

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