Structural Health Monitoring under Varying Environmental Conditions Using Wavelets

Abstract

A novel structural health monitoring system to detect damages in structures under varying operational and environmental conditions is presented in this paper. A noncontact, full-field measurement using a high speed camera offers a convenient and less expensive measurement procedure, enabling the measuring of responses in elevated temperatures and in conditions where contact sensors are unable to be used. In this paper, a combination of Decay lines of the Wavelet Transform Modulus Maxima (WTMM) and Holder Exponent (HE) are used to distinguish changes on the time response of a vibrating structure due to the operational and environmental variations to changes due to the presence of damage, thus minimising the possibility of false alarm. The proposed methodology is demonstrated using a 3-DOF system under conditions of varying and constant temperatures with the presence of damage, as well as using an experimental setup of a cantilever beam under intact and damaged conditions.