Damage Identification in Active Plates with Indices Based on Gaussian Confidence Ellipses Obtained of the Electromechanical Admittance

Abstract

Structural health monitoring (SHM) is an important area of study in the diagnosis of structural failures. Through SHM, structures can be diagnosed by electromechanical impedance (EMI) technique to detect changes in operative state. The signals of EMI obtained from piezoelectric transducers (PZT) are processed to quantify and classify damage severities by means of indices. These indices are studied and analyzed to recognize damage patterns in the electrical signals emitted by PZTs. In this research, an experimental analysis is carried out to identify structural damage in active plates with indices based on Gaussian confidence ellipses of the EM admittance. Three experimental tests are performed to assess the feasibility of the indices in the damage identification. A damage metric is depicted in each test together with the conductance (G) and susceptance (B), which were analyzed from different points of view. A probabilistic procedure is established to estimate Gaussian ellipses from a structure without damage with the aim to establish an alert baseline before that damage is induced. The results show that using the proposed methodology, the damage identification is a feasible procedure in the proposed case studies. Therefore, the presented analysis can be extrapolated to other applications to identify damage and so to test the feasibility of the methodology in other context.