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TitleAcoustic emission during fatigue experiments on first year sea ice
Publication TypeJournal Article
Year of Publication1996
AuthorsLanghorne, P.J., and Haskell T.G.
JournalCold Regions Science and Technology
Pagination237 - 250
Date Published1996
ISSN0165232X (ISSN)
Keywordsacoustic emission, Acoustic emissions, Acoustic transducers, Attenuation, Cantilever beams, Cyclic loading, Estimation, Fatigue of materials, fatigue test, Fracture, Geometry, ice fracture, Light, Light emission, loading test, Microcracks, Rayleigh surface wave, Sea ice, Surface waves
AbstractAcoustic emission events were measured during the cyclic loading of cantilever beams of sea ice. The events were detected with resonant transducers, with bandwidth 20 kHz to 150 kHz, which are predominantly sensitive to the vertically polarized component of the Rayleigh surface wave. This confinement to the surface, along with the linear geometry of the beam, make it possible to estimate a one dimensional source location with only two transducers. We define an event magnitude and find that this magnitude increases as the load increases, with the largest energy release occuring during the fracture of the beam. The measurement of magnitude requires an estimate of the high frequency attenuation of the Rayleigh waves in sea ice. In the absence of existing data in the literature, we make our own estimate and compare this with suitably adjusted data for compressional waves. The sources of the events are precursors to the eventual fracture of the sea ice, having highest density at the location of the final failure of the beam. We speculate that the emissions originate either from dislocation breakaway or the microcracking associated with this dislocation motion. By measuring the slope of the cumulative magnitude-frequency plot we may surmise that our data are consistent with the view that the system is organising itself into a stationary critical state.

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