Topic
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: The spatial distribution of various properties attributed to the cavitation field generated by a shock wave lithotripter are examined, including acoustic emission and sonoluminescence, which result from violent bubble collapse, and the degree of cell lysis in vitro, which appears to be related to cavitation.
Abstract: This study examines the spatial distribution of various properties attributed to the cavitation field generated by a shock wave lithotripter. These properties include acoustic emission and sonoluminescence, which result from violent bubble collapse, and the degree of cell lysis in vitro, which appears to be related to cavitation. The acoustic emission detected with a 1 MHz, 12 cm diameter focused hydrophone occurs in two distinct bursts. The immediate signal is emitted from a small region contained within the 4 MPa peak negative pressure contour. A second, delayed, burst is emitted from a region extending further along the beam axis. The delay between these two bursts has also been mapped, and the longest delay occurs at positions close to the regions of maximum peak negative pressure. Sonoluminescence from both single and multiple shocks occurs in a broader region than the acoustic emission but the measurement technique does not allow time resolution of the signal. Cell lysis occurs in a relatively small region that correlates closely with the immediate acoustic emission for a shock propagating in a gelatine solution.
64 citations
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TL;DR: In this article, principal component analysis and Sammon mapping were used to reduce the dimension of acoustic emission (AE) signals generated by damage to a structure, namely, a box girder from a bridge.
Abstract: This paper is concerned with the compression or dimensional reduction of a number of acoustic emission (AE) signals generated by damage to a structure, namely, a box girder from a bridge. The object of the exercise is to visualise the data and thereby associate clusters tothe measured AE bursts. These can be used tohelp interpret the signals. Two methods are used to reduce the dimension: principal component analysis and Sammon mapping.
64 citations
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TL;DR: In this paper, the effects of chemical environment (dry versus solution flooded), grain size (d=196-378 mu m), and applied effective stress (sigma(a) up to 30MPa), at room temperature conditions favoring grain-scale brittle processes were investigated.
Abstract: Time-dependent brittle creep plays a role in controlling compaction of sands and sandstones under upper crustal conditions, influencing phenomena such as production-induced reservoir compaction, surface subsidence, and induced seismicity. Brittle creep also plays a role in determining the mechanical behavior of gouge-rich faults. We performed uniaxial creep experiments on sand to investigate the effects of chemical environment (dry versus solution flooded), grain size (d=196-378 mu m), and applied effective stress (sigma(a) up to 30MPa), at room temperature conditions favoring grain-scale brittle processes. Creep measurements were complemented with acoustic emission (AE) detection and microstructural analysis to characterize the main creep mechanism. Wet samples showed much higher creep strains than dry-tested samples. AE event counts showed a direct relation between grain failure and creep strain, with higher AE rates occurring in the wet samples. Therefore, we inferred that time-dependent deformation was dominated by subcritical crack growth, resulting in grain failure accompanied by intergranular sliding rearrangements, and that crack growth in the presence of chemically active fluids was controlled by stress corrosion. The sensitivity of the compaction rate of the sands to d and sigma(a) can be expressed as (epsilon) over bar proportional to d(i)sigma(j)(a) where i approximate to 6 and j approximate to 21 under dry conditions and i approximate to 9 and j approximate to 15 under wet conditions. Our results were compared to a simple model based on Hertzian contact theory, linear elastic fracture mechanics, and subcritical crack growth. This model showed agreement between the observed stress and grain size sensitivities of creep, within a factor of 2.
64 citations
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TL;DR: In this article, a numerical approach using bonded-particle model (BPM) was adopted to simulate the loading processes and acoustic emission (AE) events of limestone, which revealed that the AE parameters in the BPM including crack number and AE event were generally comparable with the AE count and AE hit in the experiments.
64 citations