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Structural Engineering and Mechanics
  Volume 25, Number 6, April20 2007, pages 691-716
DOI: http://dx.doi.org/10.12989/sem.2007.25.6.691
 


A robust identification of single crack location and size only based on pulsations of the cracked system
Jean-Jacques Sinou

 
Abstract
    The purpose of the present work is to establish a method for predicting the location and depth of a crack in a circular cross section beam by only considering the frequencies of the cracked beam. An accurate knowledge of the material properties is not required. The crack location and size is identified by finding the point of intersection of pulsation ratio contour lines of lower vertical and horizontal modes. This process is presented and numerically validated in the case of a simply supported beam with various crack locations and sizes. If the beam has structural symmetry, the identification of crack location is performed by adding an off-center placed mass to the simply supported beam. In order
to avoid worse diagnostic, it was demonstrated that a robust identification of crack size and location is possible if two tests are undertaken by adding the mass at the left and then right end of the simply supported beam. Finally, the pulsation ratio contour lines method is generalized in order to be extended to the case of rectangular cross section beams or more complex structures.
 
Key Words
    vibration; crack; identification.
 
Address
Laboratoire de Tribologie et Dynamique des Systemes UMR-CNRS 5513, Ecole Centrale de Lyon,36 avenue Guy de Collongue, 69134 Ecully Cedex, France
 

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