REVERSED DIRECT-STRESS TESTING OF ICE - INITIAL EXPERIMENTAL RESULTS AND ANALYSIS

This paper focusses on the analysis and discussion of the results of a series of reversed direct-stress experiments performed on freshwater ice. A companion paper (Cole and Gould, this issue) describes the apparatus developed for these experiments. The experimental technique provides a means to subject cylindrical ice specimens to fully reversed (i.e., alternating tension/compression) uniaxial loading, thereby permitting the study of cyclic-loading effects under a uniform stress field. The topics include frequency, temperature and strain-amplitude effects on internal friction; cyclic loading-history effects on tensile strength, grain-size effects on cyclic stress-strain behavior and the Bauschinger effect. The observations are discussed in terms of the mechanisms underlying the behavior, with particular attention to dislocation processes. The observations indicate the operation of the dislocation breakaway process and the Granato-Lucke theory models the associated amplitude-dependent internal friction results extremely well. © 1990.