Acoustic emission analysis (AE) is part of a non-destructive testing method used to detect and analyze damage inside a material. Due to the internal and external damage of the component, elastic waves are generated under load, which are virtually radiated by the resulting cracks and micro-fractures. Such signals can be recorded and evaluated by sensors on the surface of the component, allowing conclusions to be drawn about the condition of the material and the cause of the deformation. AE has been used for more than 40 years, but the great effort required to evaluate the measurements and the lack of automatic evaluation procedures are reasons why AE is still impractical and not widely used. At the Technische Hochschule Mittelhessen (THM) in Germany, AE is used to further develop this non-destructive measurement method on a reinforced concrete beam under a 4-point bending load in combination with a digital image correlation system (DIC). Using AE, it is possible to record the crack initiation inside the structural member with a small location error of less than 30 mm. The DIC Systems records relative displacements between load levels, making it possible to record concrete strains, cracks and deformations on the surface of the component. The reinforced concrete beam to be tested fails very brittle on shear force due to its reinforcement arrangement. Monitoring the experiment with the AE is intended to show when bending cracks develop and when a shear force failure is imminent. In the final step, the experimental results will be compared and validated with a nonlinear numerical simulation. The goal of this paper and further investigations is to optimize the components as well as the evaluation procedure and thus to extend the AE to the application for existing dynamically loaded structures such as bridges or wind turbines.

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Experimental Investigations of a Reinforced Concrete Beam Under Shear Force Failure for the Validation of Nonlinear Numerical Calculations with Acoustic Emission Analysis

  • Manuel Koob,
  • Niklas Lingner,
  • Dennis Bohn,
  • Jens Minnert,
  • Gerd Manthei

摘要

Acoustic emission analysis (AE) is part of a non-destructive testing method used to detect and analyze damage inside a material. Due to the internal and external damage of the component, elastic waves are generated under load, which are virtually radiated by the resulting cracks and micro-fractures. Such signals can be recorded and evaluated by sensors on the surface of the component, allowing conclusions to be drawn about the condition of the material and the cause of the deformation. AE has been used for more than 40 years, but the great effort required to evaluate the measurements and the lack of automatic evaluation procedures are reasons why AE is still impractical and not widely used. At the Technische Hochschule Mittelhessen (THM) in Germany, AE is used to further develop this non-destructive measurement method on a reinforced concrete beam under a 4-point bending load in combination with a digital image correlation system (DIC). Using AE, it is possible to record the crack initiation inside the structural member with a small location error of less than 30 mm. The DIC Systems records relative displacements between load levels, making it possible to record concrete strains, cracks and deformations on the surface of the component. The reinforced concrete beam to be tested fails very brittle on shear force due to its reinforcement arrangement. Monitoring the experiment with the AE is intended to show when bending cracks develop and when a shear force failure is imminent. In the final step, the experimental results will be compared and validated with a nonlinear numerical simulation. The goal of this paper and further investigations is to optimize the components as well as the evaluation procedure and thus to extend the AE to the application for existing dynamically loaded structures such as bridges or wind turbines.