Identifying damage using local flow variation method

Abstract

In this paper, a damage identification method called local flow variation is introduced. Itis a practical implementation of a phase space warping concept. A hierarchicaldynamical system is considered where a slow-time damage process causes drifts inthe parameters of a fast-time system describing the measurable response of astructure. The method is based on a hypothesis that the probability distributionfunction of the fast-time trajectory in its phase space is a function of a damagestate. In this method, an ensemble of estimated expectations of a trajectory indifferent locations of the reconstructed phase space is used as a damage featurevector. Using these feature vectors, damage identification is realized by a smoothorthogonal decomposition. An experiment is conducted to validate the method. Atwo-dimensional slow-time damage process is identified from experimental fast-time data.Although damage identification results from the local flow variation are not asaccurate as those from the direct application of phase space warping trackingfunctions, the required computation time is about two orders of magnitude shorter.