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Full-Text Articles in Engineering
Do Loading Path And Specimen Thickness Affect The Brittle Compressive Failure Of Ice?, A. L. Fortt, E. M. Schulson
Do Loading Path And Specimen Thickness Affect The Brittle Compressive Failure Of Ice?, A. L. Fortt, E. M. Schulson
Dartmouth Scholarship
Compressive experiments were performed on square (160 mm × 160 mm) prismatic specimens of columnar-grained, S2 freshwater ice, biaxially loaded across the columns at −10°C. The work focused on brittle behavior, achieved by deforming the specimens at an applied strain rate of 4.5 ± 1.2 × 10 3s 1 in the direction of shortening. The results show that the specimen thickness (25–150 mm) has no detectable effect on the terminal failure strength of the ice. Likewise, the strength of the ice when loaded under proportional loading, where the minor stress varies during the test, was similar to that when loaded …
The Effect Of Particles On Dynamic Recrystallization And Fabric Development Of Granular Ice During Creep, Min Song, Ian Baker, David M. Cole
The Effect Of Particles On Dynamic Recrystallization And Fabric Development Of Granular Ice During Creep, Min Song, Ian Baker, David M. Cole
Dartmouth Scholarship
The mechanical behavior and microstructural evolution of laboratory-prepared, particle-free fresh-water ice and ice with 1 wt.% (~0.43 vol.%) silt-sized particles were investigated under creep with a stress level of 1.45 MPa at −10°C. The particles were present both within the grains and along the grain boundaries. The creep rates of specimens with particles were always higher than those of particle-free ice. Dynamic recrystallization occurred for both sets of specimens, with new grains nucleating along grain boundaries in the early stages of creep. The ice with particles showed a higher nucleation rate. This resulted in a smaller average grain-size for the …
Creep Of Granular Ice With And Without Dispersed Particles, Min Song, David M. Cole, Ian Baker
Creep Of Granular Ice With And Without Dispersed Particles, Min Song, David M. Cole, Ian Baker
Dartmouth Scholarship
The effects of silt-sized particles (average diameter of 50 m m) on the compressive creep of polycrystalline ice have been studied at stress levels from 0.1 to 1.45MPa and temperatures of –12 8 C and –10 8 C. Dislocation densities during creep have been estimated using a dislocation-based model of anelasticity. The results indicate that at low concentrations (up to 4wt.% % ), particles increase the minimum creep rate. Power-law behavior with an exponent of 3 was observed for both particle-free ice and ice with 1 wt.% % particles when the stress was >0.3 MPa. In contrast, linear behavior was …
On The Strain-Rate Sensitivity Of Columnar Ice, M. E. Manley, E. M. Schulson
On The Strain-Rate Sensitivity Of Columnar Ice, M. E. Manley, E. M. Schulson
Dartmouth Scholarship
A power law relation between stress and strain rate of the form σ ∝ ε̇1/n was used to describe the response to strain rate of S1 ice loaded across the columns at -10°C. The rate exponent, n, decreased with increasing strain from about 4.6 at an observed peak on the load displacement curve to approximately 2.6 at a shortening of 2%. Analysis of these results and of the results of other authors on different forms of ice deformed at the same temperature suggests that the power law exponent, n, is proportional to Fc/Fg. The parameter Fc/Fg is the far-field basal …
Across-Column Cracks And Axial Splits In S2 Saline Ice Under Compression, E. M. Schulson, S. Qi, J. S. Melton, E. T. Gratz
Across-Column Cracks And Axial Splits In S2 Saline Ice Under Compression, E. M. Schulson, S. Qi, J. S. Melton, E. T. Gratz
Dartmouth Scholarship
Experiments on plate-like specimens have established that across-column cracks from within S2 (columnar) salt-water ice when compressed uniaxially along a direction inclined to the long axis of the grains. Wing cracks initiate from the across-column cracks and lengthen into axial splits when the ice is rapidly deformed; correspondingly; the macroscopic behavior changes from ductile to brittle. The across-column cracking is attributed to grain-boundary sliding, and the splitting to the suppression of crack-tip creep.
Brittle Compressive Failure Of Salt-Water Columnar Ice Under Biaxial Loading, T. R. Smith, E. M. Schulson
Brittle Compressive Failure Of Salt-Water Columnar Ice Under Biaxial Loading, T. R. Smith, E. M. Schulson
Dartmouth Scholarship
The brittle failure of saline columnar ice was investigated under biaxial compression at and −10° and −40°C over the range 0 ≤ R A < 1 where R A is the ratio of the intermediate to major principal compressive stress. The major principal stress and the intermediate (confining) stress were orthogonal to the columnar axes (type-A confinement); both stresses and the c-axes of the grains were co-planar. The results confirm earlier work by Hausier (1981) and Timco and Frederking (1983, 1986) on saline ice and follow similar behavior to fresh-water columnar ice found by Smith and Schulson (1993) and Frederking (1977). Failure stress and failure mode are sensitive to the confinement and two regimes of behavior are found: the failure stress first rapidly increases with R A in the range 0 ≤ R A < R T and then tends to decrease for R A > R t. The transition stress ratio, R t changes from ≈0.2 at −10°C to ≈0.1 at −40°C. The failure mode changes from axial splitting to shear faulting in the loading plane for 0 < R A < R t. Above R t failure changes to a combined mode of splitting across the columns and shear faulting out of the loading plane. The failure-stress envelope is of a truncated Coulomb-type. Damage studies show wing cracks and local fragmentation of grains involving the brine pockets. The results are explained in terms of Coulombic sliding and Hertzian crack mechanics.
The Fracture Of Ice On Scales Large And Small: Arctic Leads And Wing Cracks, E. M. Schulson, W. D. Hibler
The Fracture Of Ice On Scales Large And Small: Arctic Leads And Wing Cracks, E. M. Schulson, W. D. Hibler
Dartmouth Scholarship
From observations and calculations of crack patterns in ice, it is suggested that a similar mechanism may account for cracking over a wide range of scales.