Damage severity and propagation characterization with admittance signatures of piezotransducers

Abstract

The electromechanical (EM) impedance method is emerging as an effective tool forstructural damage detection. Damage is detected by changes in the EM impedancesignatures of the smart piezoelectric transducer bonded on the structure. The damagequantification has so far been restricted to using non-parametric statistical indices tomeasure changes in the signatures. Such measures, although simplistic, fail tocorrelate the changes in the signatures to physical parameters of the structures.Thus, although effective in detecting the presence of damage, the method fails togive further information about the location and severity of the damage. In thispaper, the EM impedance method integrated with a finite element (FE) modelis presented as a means for characterizing damage growth. Damage growth ischaracterized by quantifying the changes in the natural frequency shifts of the structureextracted from the EM admittance signatures. A new damage characterization indexis derived, which is experimentally validated to be capable of distinguishing alocalized increase in severity from damage propagation through the structure.