Abstract
Acoustic emission (AE) source location is an effective method used to reveal the deformation and damage characteristics of materials. Improving the positioning accuracy of AE events is extremely important for both experimental research and engineering practice. An experiment was performed on a standard rock specimen to investigate the key factors that affect the positioning accuracy of an AE event, such as the computational combinations and spatial layout of the sensors and the picking accuracy of the first arrival signal. The results show that as the number of sensors involved in the positioning calculation increases, both the maximum and average positioning errors clearly decrease, and the positioning accuracy increases. Meanwhile, a better result is achieved when the number of sensors involved in the positioning calculation reaches three-fourths of the total number of monitoring sensors used. Under this condition, both the minimum positioning error and the error dispersion are sufficiently low, and the reliability of the positioning results is greatly improved. Furthermore, when different types of and deviations in the first arrival signal are used for the location calculation of the same AE event, the positioning results are quite different, and large errors are found. Finally, the accurate positioning of an AE event is realized by adjusting the number of sensors and improving the picking accuracy of the first arrival time of the signal. The maximum reduction in the positioning error achieved is 96.62%, and the minimum reduction is 57.61%. Hence, the positioning error decreases significantly. The investigation results can provide an important reference for the precise positioning of AE events involved in experimental research and engineering.
Highlights
As part of the irrecoverable energy dissipation due to the plastic straining of a stressed material, acoustic emission (AE) is highly associated with the material’s failure
The spatial positions of these AE events are obtained by microscopic image analysis (Table 2)
When the number of sensors increases from four to twelve, the maximum positioning error changes from 100.472 mm to 12.641 mm, which is a reduction of 60%, and the average positioning error changes from 24.328 mm to 12.641 mm, which is a reduction of 48%
Summary
As part of the irrecoverable energy dissipation due to the plastic straining of a stressed material, acoustic emission (AE) is highly associated with the material’s failure. The main purpose of AE localization is to confirm the spatial positions of internal seismic events induced by fracture initiation and propagation. During the microcrack fracturing process, the spatial scales and evolution features of the internal microcracks can be confirmed to provide rational, objective evaluation of the material breakage degree [8], [9]. The positioning accuracy of AE events is low, and the regularity and reliability are poor in many laboratory experiments and engineering practices [10]–[12]. A higher positioning accuracy can lead to a deeper understanding of the microcrack evolution in a material. The positioning accuracy of AE events has become a notable geophysical parameter that determines the efficiency and reliability of AE monitoring
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