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| Investigation on crack identification in the beam-type structures |
| Revised:April 19, 2004 |
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| DOI：10.7511/jslx20063056 |
| KeyWord:vibration,parameter identification,transfer matrix,cantilever beam |
| WANG Zhi-hua ZHAO Yong-gang MA Hong-wei |
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| Abstract: |
| In this paper,the local effect of "softening" at the crack location can be simulated by an equivalent spring connecting the two segments of the beam. This model using the transfer matrix method in conjunction with the BernoulliEuler theories of beam vibration,modal analysis and fracture mechanics principle are applied to derive characteristic equation,which relates the natural frequencies,the boundary conditions including the more realistic(elastic) end supports to crack parameters.The procedure proposed is advanced by elimination of numerical computation of the high order determinant so that the computer time for calculating natural frequencies in consequence is significantly reduced.Furthermore,from this expression,two accurate crack identification methods are developed,which only require the variation of the first several natural frequencies due to the crack,with no other information needed concerning the beam geometry or material and the crack depth or shape.The proposed approaches are verified by simulated damage in the form of one-side cracks in a cantilever beam. |
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