Abstract
To determine the minimum crack width that can be detected using the impact-echo method, two types of laboratory experiment on concrete plate specimens were conducted. In each experiment, a crack was propagated through the plate parallel to the plate surfaces, while surface displacements caused by the crack opening were measured and impact-echo tests were performed along the crack trajectory. The relationship between the surface displacements and the real crack-opening displacements was established using the results of nonlinear fracture analyses. The minimum crack width was determined by estimating the crack-opening displacements for each impact-echo test location. As a result of this work, the minimum crack width which can be detected was found to be 0.025 mm, and the minimum crack width for which stress waves are not transmitted across the crack faces was found to be 0.08 mm. This paper describes how crack-opening displacements were determined using nonlinear fracture analyses.
Resume
On a exécuté deux types d'essais en laboratoire sur des échantillons de plaques de béton afin de déterminer quelle est la fissure minimale détectable par la méthode d'émission acoustique. Dans chaque essai, une fissure était propagée à travers la plaque parallèlement à la surface, tandis que le déplacement superficiel entraîné par l'ouverture de la fissure était mesuré et des essais d'émission acoustique réalisés le long du trajet de la fissure. En utilisant les résultats des analyses de rupture non linéaire, on a établi la relation entre le déplacement superficiel et le déplacement de la véritable ouverture causée par la fissure. On a déterminé la largeur minimale de la fissure par l'estimation des déplacements d'ouverture à chaque point par la méthode d'émission acoustique. Il résulte de cette étude que la largeur minimale de fissure détectable était de 0,025 mm et que la largeur minimale pour laquelle aucune onde de contrainte ne se propage dans les bords de la fissure était de 0,08 mm. Ici, on décrit comment, en utilisant les analyse de rupture non linéaire, on a déterminé les déplacements créés par l'ouverture de la fissure.
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Cheng, CC., Sansalone, M. Determining the minimum crack width that can be detected using the impact-echo method Part 2. Numerical fracture analyses. Materials and Structures 28, 125–132 (1995). https://doi.org/10.1007/BF02473219
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DOI: https://doi.org/10.1007/BF02473219