Nonlinear piezoelectric impedance modulation induced by a contact-type failure and its application in crack monitoring

Abstract

In this paper, a self-sensing, sensitive and baseline-free structural health monitoring methodology is developed, which aims to detect and characterize local structural failures of contact type, i.e. failures which arise along with the generation, growth and/or changes of imperfect solid-solid interfaces. The nonlinear piezoelectric impedance modulation (NPIM) method presented is based on the ideas of two existing damage detection principles; a piezoelectric impedance-based methodology and a nonlinear wave modulation spectroscopy. It uses a single piezoelectric active sensor bonded on the structural surface, which is driven by a high-frequency harmonic voltage source. When the structure including a contact-type failure is subjected to a low-frequency dynamic load, the induced structural vibration causes a fluctuation of the scattering conditions for the high-frequency elastic waves at the failure because of the contact acoustic nonlinearity (CAN). This nonlinear effect of vibro-acoustic interaction yields a significant fluctuation in the driving-point impedance in the high-frequency range, which may lead to a modulation of the coupled electromechanical impedance (or admittance) of the piezoelectric active sensor. Therefore, if the sensor is driven by a fixed amplitude high-frequency harmonic voltage source, modulation of the coupled admittance can be observed as the amplitude modulation and phase modulation of the current flowing through the sensor. A simplified modeling study leads to the definition of a damage evaluation index that assesses the intensity of the stiffness fluctuation caused by the CAN. Experiments using cracked beam specimens are conducted to show how the NPIM can be observed and to examine the performance of the proposed method.

Quantitative evaluation of residual torque of a loose bolt based on wave energy dissipation and vibro-acoustic modulation: A comparative study

“…To circumvent the said deficiencies, a great deal of effort has been directed to the development of alternative methodologies making good use of linear or nonlinear features of acoustic waves, based on a promise that a loose bolt, showing somewhat similar behaviors like damage, scatters incident acoustic waves propagating in the joint and introduces changes in either linear signal features (e.g., energy dissipation [10], delay in time-of-flight (ToF) [11], reflection/transmission [12], and mode conversion [13]) or nonlinear signal features (e.g., high-order harmonic generation, and shift in resonance frequency [14][15][16][17][18][19]).…”

Evaluation of fatigue cracks using nonlinearities of acousto-ultrasonic waves acquired by an active sensor network

“…Other efforts making use of nonlinear features of AU waves also include those based on nonlinear surface waves [25], contact acoustic nonlinearity (CAN) [26], dual frequency mixing [27] or time reversal [28], etc. Despite their demonstrated effectiveness in indicating the existence of fatigue damage, most approaches suffer from drawbacks when used for developing automatic SHM techniques, because of:…”