ORCID Profile
0000-0002-0282-6565
Current Organisation
University of Adelaide
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Publisher: AIP Publishing
Date: 09-03-2020
DOI: 10.1063/1.5142416
Abstract: The measurement and evaluation of nonlinear elastic properties represents a great interest in materials science and engineering. These measurements can be conducted using the internal resonance of higher harmonics generated with ultrasonic bulk, Rayleigh, and Lamb waves. However, these waves are spatially dispersive, making the evaluation very difficult. In this paper, we present the outcomes of an experimental study on the generation of higher harmonics with the fundamental mode of edge waves. This wave mode—an analog of the Rayleigh wave—propagates along the apex of an elastic plate, where the lateral plate surfaces naturally avoid spatial dispersion. In addition, this mode is weakly dispersive in the frequency domain enabling approximate internal resonance, which is required for the measurement of material nonlinearities. The current experimental results indicate that the second harmonic of the fundamental edge wave mode grows linearly with the propagation distance. The linear rate of accumulation of this harmonic can then be related to the nonlinear elastic properties as procured by previous theoretical studies.
Publisher: Springer International Publishing
Date: 2019
Publisher: Elsevier BV
Date: 06-2022
Publisher: Elsevier BV
Date: 06-2023
Publisher: Elsevier BV
Date: 07-2019
DOI: 10.1016/J.ULTRAS.2019.02.006
Abstract: This paper presents a new method for determining the third-order elastic constants (TOECs) of a homogeneous isotropic material utilising the acoustoelastic effect associated with Rayleigh waves. It is demonstrated that the accuracy of the evaluation of TOECs can be substantially improved by supplementing the classical equations of acoustoelasticity, which describe the effect of applied stress on bulk wave speeds, with the nonlinear characteristic equation for the propagation of Rayleigh waves in pre-stressed media. The developed method can be readily implemented for Structural Health Monitoring applications for ex le, the measurement of applied stresses based on the acoustoelastic effect, or the monitoring of near-surface microstructural damage based on the change in magnitude of the TOECs.
Publisher: SAGE Publications
Date: 17-09-2019
Abstract: The in situ monitoring of stresses provides a crucial input for residual life prognosis and is an integral part of structural health monitoring systems. Stress monitoring is generally achieved by utilising the acoustoelastic effect, which relates the speed of elastic waves in a solid, typically longitudinal and shear waves, to the stress state. A major shortcoming of methods based on the acoustoelastic effect is their poor sensitivity. Another shortcoming of acoustoelastic methods is associated with the rapid attenuation of bulk waves in the propagation medium, requiring the use of dense sensor networks. The purpose of this article is twofold: to demonstrate the application of Rayleigh (guided) waves rather than bulk waves towards stress monitoring based on acoustoelasticity, and to propose a new method for stress monitoring based on the rate of accumulation of the second harmonic of large- litude Rayleigh waves. An experimental study is conducted using the cross-correlation signal processing technique to increase the accuracy of determining Rayleigh wave speeds when compared with traditional methods. This demonstrates the feasibility of Rayleigh wave–based acoustoelastic structural health monitoring systems, which could easily be integrated with existing sensor networks. Second harmonic generation is then investigated to demonstrate the sensitivity of higher order harmonics to stress-induced nonlinearities. The outcomes of this study demonstrate that the sensitivity of the new second harmonic generation method is several orders of magnitude greater than the acoustoelastic method, making the proposed method more suitable for development for online stress monitoring of in-service structures.
Publisher: Elsevier BV
Date: 11-2022
Publisher: SAGE Publications
Date: 27-05-2021
Abstract: Detection of mechanical damage using Lamb or Rayleigh waves is limited to relatively simple geometries, yet real structures often incorporate features such as free or cl ed edges, welds, rivets, ribs and holes. All these features are potential sources of wave reflections and scattering, which make the application of these types of guided waves for damage detection difficult. However, these features can themselves generate so-called ‘feature-guided’ waves. This article details the first application of the fundamental mode of transient edge waves for detection of mechanical damage. The fundamental edge wave mode (ES 0 ) – a natural analogue to Rayleigh waves – is weakly dispersive and may decay with propagation distance. The phase and group velocities of the ES 0 wave mode are close to the fundamental shear horizontal (SH 0 ) and symmetric Lamb (S 0 ) wave modes, at low and high frequencies, respectively. It is therefore quite challenging to excite a single ES 0 mode and avoid wave coupling. However, it was found experimentally that at medium range frequencies the ES 0 mode can be decoupled from SH 0 and S 0 modes, and its decay is small, allowing for distant detection of defects and damage along free edges of slender structural components. This article provides a brief theory of edge waves, excitation methodology and successful ex les of distant detection of crack-like and corrosion damage in I-beam sections, which are widely applied in engineering and construction.
Publisher: Elsevier BV
Date: 02-2023
Publisher: Elsevier BV
Date: 07-2021
Publisher: Springer International Publishing
Date: 2020
No related grants have been discovered for James Hughes.