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Abstract: A
method for identification of multiple cracks in beam-type structures is
presented. The changes in nature frequency of the structure with various
crack locations and depths are accurately obtained by means of wavelet
finite element methods, and then the surface-fitting technique is
employed to plot the surfaces of nature frequency shifts. The global
cracked beam is divided into coarse mesh and the expressions relating
changes in natural frequency and damage index matrix are formulated via
an influence matrix. Damage index matrix can be solved by the resulting
system of linear algebraic equations. The elements corresponding to the
damage indexes with positive values are predicted to contain the crack.
In each damage element, the corresponding natural frequency shifts are
used as input in multiple cracks detection process and the crack
locations and depths can be identified through finding the points of
intersection of three frequency contour lines. Numerical example is
employed to demonstrate the effectiveness of the presented method.
Key
words: Multiple
cracks Fault diagnosis Detection Wavelet finite element method
CLC No: TB21
TH12
国家973发展计划(2005CB724106)、国家自然科学基金(50335030)、教育部博士点基金(20040698026)和西安交通大学自然科学基金资助项目.
Received 20040920, received in revised form 20050406
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