Damage detection strategies based on propagation of guided elastic waves

Abstract

This paper demonstrates the effectiveness of certain structural health monitoring (SHM) strategies based on propagation of guided elastic waves within thin-walled shell structures. This is realized based on results of numerical and experimental investigations obtained by the use of the spectral finite element method (SFEM) together with laser scanning vibrometry (LSV) and subsequent application of two different integral-based indices for damage quantification, these being the integral mean value (IMV) and the root mean square (RMS). Numerical tests by SFEM were carried out for a square plate with through-hole damage, a cracked fuselage section with two stiffeners and a cracked wing section skin, all made out of aluminium. Experimental measurements by LSV included tests on a square aluminium plate, composite plate and a composite stabilizer of a PZL W-3A helicopter, all with simulated damage. During numerical and experimental investigations damage sensitivity of both IMV and RMS indices was tested by considering various displacement components, signal timescales or weighting factors. A certain practical method for quick construction of RMS damage maps based on experimental measurements by LSV was also presented.