Three-dimensional images generated from diffuse ultrasound wave: detections of multiple cracks in concrete structures

Abstract

The simultaneous detection of multiple defects in concrete structures is a task of pivotal importance for non-destructive testing and evaluation. Diffuse waves experiencing multiple scattering inside media are demonstrated to be sensitive to weak defects. Here, an analytic model is presented for diffuse wave decorrelation associated with sensitivity kernel that describes the time-of-flight distribution in strongly scattering environments. The model is then used for generating three-dimensional images that involve estimating perturbations at each localized position through an iterative, non-linear algorithm. With the consideration of loads and micro-cracks effects on diffuse waves, an application of the approach to a real-size concrete beam shows features that denote the positions and depths of multiple existing cracks. Extension of the approach to other strongly scattering media such as tissues and volcanos is straightforward. This study offers great potential for practical applications such as structural health monitoring, medical image generation, and seismic monitoring.

Condition Evaluation of an Existing T-Beam Bridge Based on Neutral Axis Variation Monitored with Ultrasonic Coda Waves in a Network of Sensors

“…More transducers and closer placement as well as analysis of different source-receiver pairs (i.e., sensor network) can lead to higher resolution. In a recent study, several other coda wave-based techniques such as maximum likelihood [ 23 ] and diffusion imaging [ 24 , 25 , 26 ] are developed for precise localization of cracks. Integrating them with this proposed technique will be an important task of our future work.…”

“…These features are well-known to severely affect the performance of traditional direct wave-based techniques. Fortunately, previous studies in the fields of optics, acoustic, and geophysics demonstrate that noise-like coda waves contain detailed information about internal structures, and they are very sensitive to changes occurring in the large volume of a medium [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ]. This sensitivity is attributed to the fact that coda waves propagate following complex trajectories not limited to the direct path between two sensors, and they may traverse the regions of interest repeatedly.…”

“…Thanks to these properties, coda waves have been successfully used for several NDT&E applications, mostly on laboratory scales. Depending on practical applications, these coda wave-based techniques can generally be separated into two categories: evaluation of global structural health [ 16 , 17 , 18 , 19 , 20 ] and characterization of cracks [ 21 , 22 , 23 , 24 , 25 , 26 ]. The first category focuses on global structure monitoring through the use of coda wave interferometry (CWI) [ 27 ] or diffusion equation [ 11 ] to quantify coda signal changes.…”

“…Its general concept is to first calculate coda waveform variations. An inversion procedure is then adopted to calculate the density of changes at each localized position through inverse algorithms, such as maximum likelihood [ 23 ], sensitivity kernel [ 24 , 25 , 26 ], and interpolation [ 21 ]. For additional details on the techniques, we refer the reader to the literature reviews published in References [ 20 , 25 ].…”

Estimation of Stresses in Concrete by Using Coda Wave Interferometry to Establish an Acoustoelastic Modulus Database

“…These features are well-known to severely affect the performance of direct wave-based detection techniques. Fortunately, it has been demonstrated that coda wave is very sensitive to changes occurring in the large volume of a medium [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. This sensitivity is attributed to the fact that coda waves propagate following complex trajectories not limited to the direct path between sensors, and they may traverse the regions of interest repeatedly.…”