Nondestructive Testing and Structural Health Monitoring Techniques for Damage Detection of Cement-based Materials
Date
2022
Authors
Yin, Tingyuan
Editors
Advisors
Ng, Alex Ching-tai
Kotousov, Andrei Georgievich
Kotousov, Andrei Georgievich
Journal Title
Journal ISSN
Volume Title
Type:
Thesis
Citation
Statement of Responsibility
Conference Name
Abstract
This thesis contains theoretical and experimental studies of non-destructive testing (NDT) and structural health monitoring (SHM) techniques for damage detection of cement-based materials. New nonlinear vibro-acoustic techniques are proposed in the study for the purposes of 1) to overcome application restriction of vibro-acoustic technique (e.g., limited frequency range of signal emitter and high power consumption for long-term monitoring), and 2) to develop a better understanding of amplitude-modulated signals propagating through medium with material nonlinearity and contact nonlinearity, and 3) to establish feasible nonlinear parameter to quantitatively assess different levels of damage in cement-based materials.
In Chapter 1, an overview of the existing vibro-acoustic technique for damage detection on cement-based materials is provided to shed light on the significance of this work. Chapter 2 introduces the previous research on SHM and NDT technique and theoretical models with material nonlinearity and contact nonlinearity.
In Chapter 3, the cross-modulated vibro-acoustic (CMVA) technique is proposed to detect damages caused by flexural tests in ultra-high-performance fibre-reinforced concrete (UHP-FRC) material. This study is a preliminary exploration of applying amplitude-modulated signals to the vibro-acoustic technique. A theoretical model is established to describe amplitude-modulated low-frequency pump wave and high-frequency probe wave propagating through the medium with concentrated crack, which can be seen as the source of contact nonlinearity.
In Chapter 4, three amplitude-modulated approaches: 1) the pure amplitude-modulated (PAM) method, 2) the suppressive amplitude-modulated (SAM) method and 3) the transmitted amplitude-modulated (TAM) method, are utilized in the low-frequency excitation in the vibro-acoustic (VA) technique to track the evolution of thermal damage in pristine graphene (PRG) mortar. Furthermore, the nonlinear parameters of these three approaches are built through building a theoretical model with material nonlinearity, where analytical solutions of nonlinear displacement of waves are obtained by solving the wave equation with second-order nonlinear terms. It is the first time that three amplitude-modulated vibro-acoustic approaches are proposed and compared from the aspects of sideband generation, power consumption, and sensitivity to damages.
In Chapter 5, the application of amplitude-modulated vibro-acoustic technique is extended to distinguish the different dosages of PRG mortar. Additionally, by solving the wave equation with second- and third-order nonlinear terms, it can be found that second- and third-order terms and higher-order perturbation assumptions are necessary to obtain more comprehensive analytical solutions of displacement of waves with three frequencies. To conclude from the study in Chapter 3 to 5, the amplitude-modulated vibro-acoustic technique can overcome the limitations of the conventional vibro-acoustic technique and be more practical, efficient, and power-saving. In addition, the proposed vibro-acoustic approaches are sensitive to the damages, particularly in the early damage state.
Chapter 6 summarizes the major contribution of this thesis and suggestions for future works.
School/Discipline
School of Architecture and Civil Engineering
Dissertation Note
Thesis (Ph.D.) -- University of Adelaide, School of Architecture and Civil Engineering, 2023
Provenance
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