Acoustoelastic effects of surface waves in concrete subjected to compressive and bending stresses
This investigation focuses on the study of acoustoelastic effects on Rayleigh surface waves (R-waves) in concrete samples subjected to 4-point load bending and uniaxial compression, considering a broad range of strain levels. The main objectives are (1) to study individually the acoustoelastic effects in tension and compression, through bending, and (2) to study the acoustoelastic effects of uniaxial compression against compression by bending. Theories of wave propagation and acoustoelasticity are presented heuristically. The most recent findings of acoustoelasticity in concrete are reviewed and discussed. Experiments consist of R-waves generated using a partially air-coupled configuration. Several wave arrival detection methods are studied and results are compared to signals simulated using a finite element model. An optimal R-wave detection method is defined for the investigation's experimental work. Preliminary acoustoelastic results are shown, where measurements are carried out simultaneously on two sides of each of four concrete specimens. These samples are tested under uniaxial compression and then in bending. Some results obtained are similar to other reported research. Acoustoelastic behaviors of opposing surfaces of same specimens are not found to be necessarily the same. Results in general are not repeatable, but two general trends are observed in the tests: (1) at equal strain levels, R-wave velocity decreases more under tension than it increases under compression, and (2) R-wave increases more in uniaxial compression than it increases in compression by bending at a given strain level.
Concrete, Acoustoelasticity, Non-destructive testing (NDT), Bending, Uniaxial Compression, Surface waves, Rayleigh waves, Ultrasound, Wave detection
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign