Damage Location Identification in Smart Beams Using Modal Parameters

Abstract

Modal analysis based damage detection techniques depend upon the accurate estimation of the changes in natural frequencies, damping ratio and mode shapes of a structure that occur with damage. But, even a large damage in a structure reflects only small shifts of the lower natural frequencies. At higher modes of vibration perceptible shifts can be observed even for occurrence of incipient damages. Yet, it is impractical to extract modal parameters at higher modes using conventional modal testing techniques. With the emerging smart piezoceramics (PZT) based damage detection technology, impedance response functions of the structure can be obtained in the higher frequencies ranges. The electromechanical admittance signature obtained in this method is a coupling of the impedances of the bonded PZT transducer and the host structure. In this paper, a unique method for damage detection that blends the modal analysis techniques with the emerging e/m impedance technique is presented. A finite element model of a cantilever beam is adopted to simulate damage and to demonstrate the possible damage identification by this method.