This paper concerns a reflection on a new decision boundary technique devoted for baseline-free damage detection purpose. Its scope focuses in studying analytically the impact of an unknown disturbance on the behavior of a monitored structure, through linear and nonlinear perturbation models. These perturbation models are introduced to interpret how an unknown disturbance away linearly and nonlinearly a monitored structure from its initial state, which is a healthy one, to its current state, which can be damaged or a healthy one that has undergone environmental/operational variations. To quantify the amount of that unknown disturbance effect, matrix perturbation theory is addressed to define two analytical bounds. The gap between them gives the decision regarding the monitored structure current state. The effectiveness of the proposed approach is demonstrated through an experimental setup of a test coupon aluminum plate, which has undergone varying loads and temperatures conditions, and crack damage cases.
doi: 10.12783/SHM2015/367