Methods for increasing sensitivity in structural damage detection based on impedance measurement of piezoelectric transducers

Author(s)

Danilo Ecidir Budoya

• Document type: Doctoral Thesis
• Press: Bauru. 2022-01-26.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Engenharia. Bauru
• Defense date: 2021-12-15
• Advisor: Fabricio Guimarães Baptista

Abstract

The measurement of electrical impedance of piezoelectric transducers is one of the most important steps in structural health monitoring (SHM) systems with damage detection based on the electromechanical impedance (EMI) technique. Many alternative measurement systems have been proposed to replace commercial impedance analyzers as they are more suitable for field applications and multi-transducer measurement. Studies reported in the literature usually analyze the performance of these systems at low frequency. However, excitation of the transducer with a high frequency, typically above 1 MHz, allows the detection of incipient damage, making it necessary to analyze measurement systems at high frequencies. Therefore, this doctoral thesis presents the results of two proposals that enable the analysis at high frequencies (above 1 MHz) and even improve the sensitivity to structural variations also at low frequencies. The first stage of this work presents results regarding the use of a negative capacitance interface together with the other elements of the measurement system. Theoretical analyzes were carried out which indicated an improvement in the sensitivity of the measurement system and, corroborating this characteristic, the results of the practical tests showed the same behavior. In the second stage, results of practical tests performed on three structures of different sizes are presented (100 cm × 5 cm × 0.2 cm, 100 cm × 10 cm × 0.2 cm and 100 cm × 25 cm × 0.2 cm) in which the amplitude of the excitation signals was varied and also their duration (through the stabilization cycles) and, according to what was obtained, this approach also presents better results at low frequencies and enables analyzes at high frequencies for all the structures used. (AU)

• FAPESP's process: 18/09312-9 - Measurement and signal acquisition techniques from piezoelectric transducers excited with high frequency signals in the structural health monitoring
• Grantee: Danilo Ecidir Budoya
• Support Opportunities: Scholarships in Brazil - Doctorate