Evaluation of acoustic emission source localization accuracy in concrete structures

Abstract

Acoustic emission source localization is a promising monitoring technique for concrete structures. However, the accuracy of acoustic emission source localization is influenced by many factors, such as the presence of cracks, which are commonly observed in existing reinforced concrete structures. In this article, the acoustic emission source localization is evaluated using a numerical model with a total number of 11,827,200 independent simulated tests. In this work, the investigated influential factors include the presence of cracks, arrival time picking error, and senor layout. The accuracy of source localization is quantified by the characteristic error defined in this article. Using the proposed wave propagation properties, a relatively stable characteristic error of 150 mm is estimated in the detection zone with the maximum sensor spacing less than 1 m. The evaluation approach and simulated characteristic error are validated experimentally by comparing the 200 manually generated signals using hammer hits on a cracked concrete beam.

Monitoring Shear Behavior of Prestressed Concrete Bridge Girders Using Acoustic Emission and Digital Image Correlation

“…For AE monitoring of such large-scale specimens, the sensor spacing needs to be controlled. Using a large sensor spacing can increase the measuring area, but may decrease the source localization accuracy [ 6 ] or falsely classify tensile cracking into friction [ 27 , 28 ]. This paper controlled the sensor spacing to be 0.5 m and 0.52 m in horizontal and vertical directions, respectively, as shown in Figure 3 , which was proven to be effective in the previous measurements on large-scale reinforced concrete structures [ 29 ].…”

“…The function is a sum of a linear function (from material attenuation, with the material attenuation factor as the slope) and a logarithmic function (from spreading loss) to the wave travel distance. The mathematical expressions can be found in [ 6 ]. By fitting the amplitude drop function to the measured data which were acquired at different travel distances ( Figure 4 b), the material attenuation factor was found to be 8 dB/m.…”

“…In this paper, the measuring area was discretized into a grid with size 5 × 5 mm. The mathematical formulation used in source localization can be found in our previous paper [ 6 ].…”

“…The distance between the actual source location and the estimated location is called the source localization error. A previous study showed an error less than 15 cm for concrete structures when four AE sensors were used [ 6 ]. The source localization error can be reduced when more sensors receive signals from the same source.…”

“…An AE event includes a group of signals that come from one source. With sufficient accuracy [ 6 ], one can find the crack profile by locating the source of AE events based on the arrival times of signals, which is called AE source localization [ 7 ]. Besides, features of AE signals can help classify different sources of AE events, which is called AE source classification [ 8 , 9 , 10 ].…”