Cyclic loading and creep response of aligned first‐year sea ice

Abstract

Abstract. Characteristics such as brine and gas porosity and crystallographic features can have a profound impact on the mechanical properties of first-year sea ice. These characteristics vary spatially and temporally, and it is important in the development of constitutive models to address their variability in physically meaningful terms. A program of laboratory experiments on field cores of first-year sea ice has been conducted to aid in the development of such models. A thorough assessment of the bulk physical properties and microstructural characteristics of the ice has been carried out in conjunction with a detailed set of cyclic loading and creep experiments. Methodology was developed to calculate an orientation factor that determines the average shear stress resolved on the basal planes, given the background normal stress. Examination of the constitutive behavior using laboratory cyclic loading and constant load creep experiments revealed that the elastic, anelastic (time-dependent recoverable), and viscous strains varied systematically with the orientation factor. The observations also indicate significant brine porosity effects on the elastic, anelastic, and viscous components of strain. A recently developed constitutive model was expanded to include a frequency-and orientation-dependent viscous straining term, and the model predictions agreed well with the experimental observation.

Monitoring the temperature-dependent elastic and anelastic properties in isotropic polycrystalline ice using resonant ultrasound spectroscopy

“…Here, we attribute pre-melt films developing at triple-junctions or on grain boundaries as the dominant mechanism for the changes in the values of the elastic properties and wave attenuation as a function of ice temperature. This is a more likely contributor than the dislocation damping mechanisms proposed to dominate at the highest temperatures (Cole et al, 1998;Cole, 1990;Cole andDurell, 1995, 2001;McCarthy and Cooper, 2016) since these samples have not been subject to deformation. This has been observed previously by Spetzler and Anderson (1968) and Kuroiwa (1964) in laboratory resonant bar measurements and in the field at seismic frequencies (Peters et al, 2012).…”

“…It is well understood that porosity, dislocation structures, the configuration of grain boundaries, and any crystallographic preferred orientation textures play an important role in the absolute value of visco-elastic dissipation (McCarthy and Castillo-Rogez, 2013;Cole et al, 1998) and elastic wave speeds (Maurel et al, 2015;Diez and Eisen, 2015;Gusmeroli et al, 2012) in ice.…”

Planetary Ices Attenuation Properties

“…Dynamic studies on non-deformed and annealed samples of polycrystalline ice have confirmed the presence of an attenuation peak at high temperatures attributed to grain boundary sliding (Cole et al 1998). Interestingly, samples that were strained to 1% showed an increase in the high-temperature background attenuation that caused the grain boundary peak to nearly disappear (Tatibouet et al 1987).…”

“…More recently, the significant bulk of work on dissipation in both laboratory grown and natural sea ice to date has been conducted by David Cole and various coworkers (e.g. Cole 1995Cole , 2001Cole et al 1998;Durell 1995, 2001). A key contribution from Cole (1995) is the development of an empirically-based model to describe relaxation in ice that is specifically tied to microstructure and defect state.…”

“…Studies on unidirectionally solidified first-year sea ice found that anisotropy affects attenuation as well. Specifically, the magnitude of dissipation was found to be proportional to an orientation factor, which is determined by the average shear stress resolved on basal planes (Cole et al 1998). So application of attenuation measurements made on laboratory prepared isotropic ice to actively deforming icy shells (where fabric formation is certainly possible) is not straightforward.…”