Using transfer function parameter changes for damage detection of structures

A novel approach is presented for damage detection of large flexible structures by using the parameter change of the transfer function. First, an interval modeling technique, which represents the system uncertainty under the environmental change via the intervals of transfer function parameters, is used to distinguish the structural damage from the environmental change. In this paper a coherence approach is developed for locating the damage position when the structural damage is observed. Only a few sensors are required in using the proposed coherence approach for damage detection. This has the advantage of using the proposed algorithm for practical applications. Also this approach has the flexibility of using the multi-input and multi-output system. A nine-bay truss example is used to demonstrate and verify the approach developed. Nomenclature a, b = denominator and numerator parameters of transfer function C = coherence of the tested system to damage G = interval model g = transfer function k = number of modes m = number of outputs n = number of tests for environmental change p = parameter vector of transfer function R = magnitude ratio of the tested system to damage R, JR = magnitude ratio bounds W = weight of parameter change Wa, W}} = weights of intervals for interval model x,y = unit vectors of Cartesian coordinate system Ap = parameter change vector Superscripts