Author: Wen, Fuzhen
Title: Shear-horizontal waves generation and reception using piezoelectric wafers for thin-plate structure damage detection
Advisors: Cheng, Li (ME)
Degree: M.Sc.
Year: 2017
Subject: Hong Kong Polytechnic University -- Dissertations
Shear waves
Structural health monitoring
Department: Department of Mechanical Engineering
Pages: xiii, 93 pages : color illustrations
Language: English
Abstract: Structural health monitoring (SHM) techniques with shear horizontal (SH) waves have shown attractive advantages due to the non-dispersion feature of the fundamental SH0 mode wave. This work investigates the SH0 wave generation and reception using d35-mode shear horizontal piezoelectric wafer sensors (SH-PWAS). Finite Element (FE) and experimental results show that not only SH0 wave but also S0 mode and A0 mode of Lamb waves can be excited and received by SH-PWAS transducers, suggesting the necessity of considering the parameter-design of the SHM system to eliminate the Lamb-wave interference to the SH0 wave. Experiments are carried out to calibrate the group velocity, dispersion curves, the amplitude-frequency relationship, as well as the intensity attenuation of the guided waves in a 1.5-thick aluminum plate. An FE model is established with four SH-PWAS transducers serving as a sensor network for the detection of a 16mm-long and 0.3mm-wide non-thickness-through crack in the plate. It is observed that additional SH0 wave generated by the crack can be captured by one SH-PWAS sensor. The mode-conversion from SH0 wave to S0 and A0 waves can be detected by another SH-PWAS sensor, providing multiple diagnosis information for the damage detection. Following the configuration of the FE model, experiments are conducted using a baseline method based on the pristine and cracked results. A fairly good agreement is found among the FE simulations and experiments, thus confirming the practicability of the proposed sensor network. This work, as a whole, establishes the fact that SH0 wave can be effectively generated and captured using SH-PWAS sensors. The study also reveals various physical phenomena which provide useful guidelines for future SH0-based SHM technology in terms of both system design and SHM diagnosis.
Rights: All rights reserved
Access: restricted access

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