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Acoustic emission
About: Acoustic emission is a research topic. Over the lifetime, 16293 publications have been published within this topic receiving 211456 citations.
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TL;DR: In this paper, a technique combining wavelet transform and conventional AE parameter analysis was developed to study the tensile failure process of thermal barrier coatings in real time, and it was demonstrated that the failure of thermal barriers originates from surface vertical cracking and follows interface cracking, and the AE count increases with tensile load following a power law.
Abstract: The fracture type differentiation, quantification, and source identification are desirable and yet intractable in the acoustic emission (AE) testing of a complex coating system. In this letter, a technique combining wavelet transform and conventional AE parameter analysis was developed to study the tensile failure process of thermal barrier coatings in real time. It is demonstrated that the failure of thermal barrier coatings originates from surface vertical cracking and follows interface cracking, and that the AE count increases with tensile load following a power law. The cracking source identified from AE signals agrees well with that observed by optical microscopy. This technique provides a powerful tool for the study of failure processes of a wide range of coatings and thin films.
66 citations
TL;DR: In this article, acoustic emission and electronic speckle pattern interferometry (ESPI) were used to quantify the fracture phenomena through AE locations and ESPI images of an intrinsic damage zone.
66 citations
TL;DR: Wang et al. as mentioned in this paper studied the differences in physical-mechanical properties and acoustic emission (AE) characteristics during deformation and fracture of thermally damaged sandstone, while simultaneously monitoring AE signals.
Abstract: An analysis of the physical–mechanical properties and acoustic emission (AE) characteristics of rock following high-temperature treatment provides theoretical guidance for detecting thermal stability in underground engineering under high-temperature conditions. The physical and mechanical properties of rock, including density, wave velocity, porosity, peak strength, elastic modulus, and deformation modulus, change after subjection to hightemperature treatment (Tian et al. 2012; Ozguven and Ozcelik 2013; Wang et al. 2015). The internal composition and structure of rock materials under such conditions undergo complex physicochemical changes, eventually resulting in cracking by thermal expansion (Chmel and Shcherbakov 2015). Sandstone is a common sedimentary rock, used in a broad array of geotechnical engineering applications and present in many coal mines (Tian et al. 2012; Zhu et al. 2016). AE technology can help deepen our understanding of deformation and fracture of rock materials after high-temperature treatment. Because of differences in mineral composition and structure, previous studies have not reported on differences in AE time domain characteristics and the spatial evolution of sandstones. In this work, we studied the differences in physical–mechanical properties and AE characteristics during deformation and fracture of thermally damaged sandstone. Uniaxial compression tests were carried out, while simultaneously monitoring AE signals. The time & Enyuan Wang weytop@263.net
66 citations
TL;DR: In this article, the authors used the discrete element method (DEM) to simulate crack initiation and propagation of polycrystalline alumina during the brittle model machining process and found that the cracks initiated right under or in front of the machining tool, some of them propagated downwards to form macro-cracks or forwards to lead material removal.
Abstract: Discrete element method (DEM) was introduced to simulate crack initiation and propagation of polycrystalline alumina during the brittle model machining process. A bonded particle model (BPM) was employed in the DEM simulations procedure to generate a particle assembly system similar to the micro-structure of the polycrystalline alumina. Particle and parallel bond properties, which were calibrated through a series of numerical tests, were subsequently used in the simulations of polycrystalline alumina cutting process and scratching tests. It is found that the cracks initiated right under or in front of the machining tool. There were many micro-cracks remained on the machined surface, some of them propagated downwards to form macro-cracks or forwards to lead material removal. Both DEM simulations and acoustic emission measure experiments have found that the fracture became acute when the normal and the tangential force changed suddenly, causing the crack number to increase. In 3D DEM scratching simulation, the surface cracks length and subsurface cracks depth linearly increased with the scratching depth, the value agreed well with the experimental results, and the surface-damage width decreased gradually with the depth to the surface, looking like half of a coin.
66 citations
TL;DR: In this paper, the uniaxial compressive strength (UCS), Young's modulus and Poisson's ratio, both static and dynamic, of the seismogenic Triassic Evaporites of the Northern Apennines were reported.
66 citations