Structural damage detection based on virtual element boundary measurement

Abstract

A “weak” formulation of the pseudo-excitation (PE) approach was recently proposed for structural damage detection in thin-walled structures. The method was shown to exhibit some appealing features including high noise tolerant ability. However, the method requires very dense displacement field measurement within the inspection region. To tackle the problem, a new damage detection method based on virtual element boundary measurement (VEBM) under the “weak” formulation framework is proposed in this paper. VEBM based “weak” formulation divides the entire structure into several “virtual elements” (VE). By tuning the vibration frequency to the natural frequency of the VE, the “weak” formulation is shown to provide a “region-by-region” detection strategy, allowing reliable damage detection by using only a small number of measurement points at the VE boundaries. The effectiveness of the proposed method was first validated numerically using a cantilever beam containing a small damage. Influences of various factors such as measurement noise levels and frequency discrepancies between the ideal and the actual elements were discussed. An experiment was carried out through a Laser Doppler Vibrometer (LDV) measurement. Results demonstrated that VEBM method can achieve good detection results by using a small number of measurement points, whilst providing enhanced noise tolerant capability against measurement uncertainties.