Evaluation of crack status in a meter-size concrete structure using the ultrasonic nonlinear coda wave interferometry

Abstract

The field of civil engineering is in need of new methods of non-destructive testing, especially in order to prevent and monitor the serious deterioration of concrete structures. In this work, experimental results are reported on fault detection and characterization in a meter-scale concrete structure using an ultrasonic nonlinear coda wave interferometry (NCWI) method. This method entails the nonlinear mixing of strong pump waves with multiple scattered probe (coda) waves, along with analysis of the net effect using coda wave interferometry. A controlled damage protocol is implemented on a post-tensioned, meter-scale concrete structure in order to generate cracking within a specific area being monitored by NCWI. The nonlinear acoustic response due to the high amplitude of acoustic modulation yields information on the elastic nonlinearities of concrete, as evaluated by two specific nonlinear observables. The increase in nonlinearity level corresponds to the creation of a crack with a network of microcracks localized at its base. In addition, once the crack closes as a result of post-tensioning, the residual nonlinearities confirm the presence of the closed crack. Last, the benefits and applicability of this NCWI method to the characterization and monitoring of large structures are discussed.

Nonlinear Coda Wave Interferometry: Sensitivity to wave-induced material property changes analyzed via numerical simulations in 2D

“…The coda wave has been shown to be reproducible [6], in containing abundant information on the medium, with very high sensitivity to small disturbances, whether localized or not, of the propagation medium [7][8][9]. Analyzing coda signals by means of "Coda Wave Interferometry" has often proven to be a powerful technique for monitoring changes in a complex medium [9,10] and imaging or locating defects [11][12][13]. In parallel, another class of characterization methods, namely nonlinear acoustic methods, has been actively developed for the non-destructive evaluation of complex materials, given their high and selective sensitivity to nonlinear scatterers such as cracks or delamination, i.e.…”

“…Inspired by both these classes of methods, a new set of methods combining nonlinear modulation and Coda Wave Interferometry was proposed by Zhang et al in 2013 for a cracked glass sample [21]. This so-called nonlinear coda wave interferometry (NCWI) method was then successfully applied to a mortar sample by Hilloulin et al [9] and subsequently to concrete [10]. In this context, we recently performed a numerical parametric study in [1] using a 2D spectral element method (SEM2D) [23] as a forward modeling tool.…”

ASR: Practical investigative techniques and field monitoring systems used to assess ASR for service life modeling.

“…14 illustrates the difference between conventional and coda wave ultrasonic monitoring, the main difference being that the latter is able to capture information from regions (highlighted in orange) that do not lie within the direct wave travel path. Over the last years, numerous researchers have started analyzing coda wave fields to monitor changes in concrete caused by cracking [14] and ASR [16]. A rigorous review of coda wave analysis techniques and their applications is provided in [15].…”

Optimization of Bifrequential Pump Excitation Parameters by Genetic Algorithm in Nonlinear Vibro Acoustic Wave Modulation Technique

“…10 tapped holes with a 4 mm diameter and localized at distances of 10 mm, 30 mm, 50 mm, 100 mm and 200 mm from each sides of the bar center are drilled. Identical screws can be placed in the tapped holes to mimic nonlinear solid contacts (cracks) such as in [11]. These holes constitute linear scatterers when no screw is present.…”