When studying the self-healing properties of construction materials, a plethora of destructive and nondestructive testing (NDT) techniques can be used. In this review, the applicability of different nondestructive test methods is discussed in detail. The methods can be categorized whether they are used to study the encapsulation and/or protection mechanism of the healing agent, the sequestered healing agent itself, the distribution of healing agents, the trigger mechanism for healing, the healing efficiency, or healing performance. Based on this categorization, nondestructive techniques found in literature are discussed. In this way, a robust understanding of the different techniques can be used for future research on self-healing construction materials.

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Validation of Self‐Healing Properties of Construction Materials through Nondestructive and Minimal Invasive Testing

Stress in laser cladding coating is an important factor affecting the safe operation of remanufacturing components. Ultrasonic testing has become a popular approach in the nondestructive evaluation of stress, because it has the advantages of safety, nondestructiveness, and online detection. This paper provides a review of ultrasonic testing for stress in remanufacturing laser cladding coating. It summarizes the recent research outcomes on ultrasonic testing for stress, and analyzes the mechanism of ultrasonic testing for stress. Remanufacturing laser cladding coating shows typical anisotropic behaviors. The ultrasonic testing signal in laser cladding coating is influenced by many complex factors, such as microstructure, defect, temperature, and surface roughness, among others. At present, ultrasonic testing for stress in laser cladding coating can only be done roughly. This paper discusses the active mechanism of micro/macro factors in the reliability of stress measurement, as well as the impact of stress measurement on the quality and safety of remanufacturing components. Based on the discussion, this paper proposes strategies to nondestructively, rapidly, and accurately measure stress in remanufacturing laser cladding coating.

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Progress and Challenges of Ultrasonic Testing for Stress in Remanufacturing Laser Cladding Coating.

Domain wall characterization inside grain and around grain boundary under tensile stress


 When stress in concrete exceeds certain threshold value, microcracks are nucleated, these microcracks can propagate and coalesce forming macrocracks, resulting in the gradual decay of the mechanical properties of concrete and eventual failure of the concrete structures. For safety concerns, one needs to develop suitable nondestructive testing methods capable of detecting past overloads of concrete structures during its service life. In this work, the stress-induced damage in concrete is monitored using ultrasonic techniques, exploiting the coupling between the stress level experienced by concrete and its wave propagation parameters. Cyclic compression tests with increasing maximum load level have been performed on specimens made of concrete with coarse-grained (CG) aggregates. Experimental results have been analyzed by two different ultrasonic methods—the linear and the nonlinear ultrasonic techniques. In linear ultrasonic technique, the stress level experienced by the specimens is related to the variations in signal amplitude and velocity of ultrasonic waves. In nonlinear ultrasonic method, the sideband peak count (SPC) technique is used for revealing the stress-induced damage corresponding to each load step. In comparison to linear ultrasonic parameters, the nonlinear ultrasonic parameter SPC-I appears to be more sensitive to the variations of the internal material structures during both loading and unloading phases. Moreover, the SPC technique has shown to be capable of identifying both the initial damage due to the evolution and nucleation of microcracks at the microscopic scale, and the subsequent damages induced by high overload, resulting in an irreversible degradation of the mechanical properties.

Linear and Nonlinear Ultrasonic Techniques for Monitoring Stress-Induced Damages in Concrete

James Martin Hughes, James Vidler, Ching-Tai Ng, Aditya Khanna, Munawwar Mohabuth, LR Francis Rose, Andrei Kotousov

/pdf/comparative-evaluation-of-in-situ-stress-monitoring-with-2bze5izt3j.pdf

Comparative evaluation of in situ stress monitoring with Rayleigh waves

Ultrasonic tests in the evaluation of the stress level in concrete prisms based on the acoustoelasticity

Abstract Changes in the stress state of a solid medium cause small variations in wave propagation velocities. Cross-correlation (CC) is a tool used for similarity evaluations between two data series. This paper addresses the use of the CC function for the feature extraction of ultrasonic test data that evaluated the stress state in a concrete specimen subjected to compressive loads. The CC function was applied to waveforms, and an analysis of influential parameters (e.g., CC-Domain, time window, and center-time) assessed the differences between the various stress levels. The results showed the variations in ∆V/V0 vs. stress diagrams were lower in the elastic regime, whereas the analyzed parameters highly influenced the results. S-waves were more suitable for analyses of stress variation, since they were little influenced by time window and center-time.

Karen F. Bompan

Papers

Ultrasonic tests in the evaluation of the stress level in concrete prisms based on the acoustoelasticity

Cross-correlation for feature extraction applied to ultrasonic test for stress evaluation in concrete