On the convergence of multiple excitation sources to a two-tone excitation class: Implications for a global optimum excitation in active sensing for structural health monitoring

Abstract

We showed in a recent study that the parameters of a system of ordinary differential equations (ODEs) may be adjusted via an evolutionary algorithm (EA) to produce deterministic excitations that improve damage detection in a simple computational spring–mass system. In that study, frequency considerations were found to be dominant, but the exact mechanism by which detection improvement is effected was not immediately apparent. In this work, an EA is used to shape bandlimited noise excitations in the frequency domain such that improvement is seen in the sensitivity of the detection feature. Tailored excitations generated from three bandlimited excitation sources, a multi-tone (linear sum of sinusoids) excitation source, and an ODE excitation source complement results from the previous study and help explain what excitation frequency characteristics are important for improved damage discernment. The convergence of all excitation source optimizations to similar solutions suggests the existence of a class of excitations that are globally optimal for improved damage detection sensitivity in the model application. Copyright © 2008 John Wiley & Sons, Ltd.