Global Status Assessment Based on the Lower Eigenvalues

A global status assessment scheme based on the lower eigenvalues is proposed to detect the damages in the existing structure. Firstly, a real structure is parameterized as analytical model by finite-element method, which is divided into identified part and non identified part according to chief and subordinate freedom degrees. The subordinate freedoms are condensed with Guyan reduced freedom method. The error estimator between the real structure and its analytical model is defined, and the algorithm of damage detection is developed. Finally a numerical example is presented to study the properties of the scheme by investigating the error extents of the identified results influenced by the number of measured frequency ranks in detail. The results illustrate that the proposed procedure is effective and useful.