Damage detection on hollow cylinders by Electro-Mechanical Impedance method: Experiments and Finite Element Modeling

Abstract

Damage detection using the Electro-Mechanical Impedance method (EMI) is based on measuring the electrical impedance spectrum of piezoelectric wafer active sensors (PWAS) attached to the structure. Any changes in the structure, such as a crack, lead to changes in the mechanical impedance of the structure, which affect the PWAS electrical impedance by the electromechanical coupling effect of PWAS. The motivation here is to examine the performance of the EMI technique for damage detection on hollow cylinders. For this purpose, the EMI technique on hollow cylinders was implemented experimentally. Damage detection was realized by comparison of damage metrics extracted from measured PWAS electrical impedance for undamaged and damaged cylinders. A Finite Element Model (FEM) of a hollow cylinder considering the EMI technique has been developed. FEM results are in accordance with experimental data and similar trends are also observed for damage metrics. The influence of different damage types and damage location on damage metrics has been explored both by experiments and FEM. Moreover, the effects of accumulated damage on damage metrics are explored both by FEM and experiments. To examine the influence of host material stiffness on damage metrics, the EMI technique was performed on aluminum and steel hollow cylinders with different thicknesses.