Author(s): P. J. Langhorne; T. G. Haskell
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Keywords: No Keywords
Abstract: Preliminary measurements have begun to characterise the fatigue behaviour of sea ice. T. he met40d used in these tests has been the repeated bending of cantilever beams. This allows the sea. ice io be tested in situ, preventing erroneous effects induced by the draining of brine from the material. As an essential step in understanding the role of damage in the fatigue of sea ice, we first consider the response of cantilever beams (nominally 10 m x 1 m x 2 m) of first year sea ice to monotonic loading. Damage is assessed using acoustic emission techniques. Interest in the production of acoustic emissions in sea ice has mainly been targeted at frequencies below 10 kHz and at naturally produced events. Higher frequency emissions, while boasting the obvious advantage of improved resolution, suffer from strong attenuation within the sea ice. As a compromise, acoustic emission events with a spectral content from 7.5 kHz to 167 kHz were monitored. Here two acoustic emission transducers have been used to estimate the location of the source on the upper surface of the sea ice sheet. The acoustic signatures associated with cracking in tension are· contrasted with those in compression. Crack speed estimates are compared with values from the literature.
Year: 1996