Fatigue Behavior of Cantilever Beams of Saline Ice

Abstract

A series of in-situ flexural strength and cyclic stress tests were carried out on laboratory-prepared NaCl ice beams, whose average growth rates exceeded those of sea ice. The flexural strengths were all found to be within the accepted range for sea ice, with those beams grown at the slowest rate being strongest, confirming our use of NaCl ice as a sea ice analog. The direction of loading had no observable effect on either the flexural strength or the tangent modulus. An S-N diagram showed no evidence of a fatigue limit nor any significant difference for two different loading frequencies (0.11 and 0.06 Hz). There was no significant dependence of N on porosity of the ice. Loss tangents were typically in the range 0.15–0.25, remaining relatively constant over the duration of the test. The tangent modulus showed considerable variation over the beam population as a whole, and for individual beams decreased steadily over the duration of the test. The loss tangent and tangent modulus showed transient effects for some beams and not others.