The plasticity of polycrystalline ice

Goodman, D. J.; Frost, H. Robert; Ashby, Michael F.

doi:10.1080/01418618108240401

Cited by 107 publications

(70 citation statements)

References 52 publications

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“…Several physical and microstructural characteristics influence its strength. Low lattice (and grain-boundary) diffusivity, leading to relatively slower matrix relaxation, and larger grains (usually > 1 mm), leading to slower grainboundary diffusion, are primarily responsible [8].…”

Section: Introductionmentioning

confidence: 99%

Crack-enhanced creep in polycrystalline material: strain-rate sensitive strength and deformation of ice

Sinha

1988

J Mater Sci

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/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. Science, 23, 12, pp. 4415-28, 1988 Crack-enhanced creep in polycrystalline material: strain-rate sensitive strength and deformation of ice Sinha, N. K. A non-linear viscoelastic creep equation for polycrystalline material is presented. It incorporates the effect of cracking and is capable of describing primary, secondary and tertiary behaviour. The model predicts the formation of microcracks and thus the damage state due to the high-temperature grain-boundary embrittlement process. This paper describes its application in formulating crack-enhanced creep and material response under constant strain-rate loading conditions (theoretically the simplest case but actually the most difficult to maintain). The formulation makes it possible to define the rate effect on stress-strain response and the rate sensitivity of strength, failure time, failure strain, damage and damage rate, strain recovery, etc. Numerical correspondence between theory and experiment was observed when predictions were compared with available closed-loop, controlled, constant strain-rate strength and deformation data on pure ice. Calculations made use of material constants determined from independent constant-load creep tests. Journal of Materials

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Section: Introductionmentioning

confidence: 99%

Crack-enhanced creep in polycrystalline material: strain-rate sensitive strength and deformation of ice

Sinha

1988

J Mater Sci

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“…The linear portion has a slope of Q /nR = 714. Below 8.3°C, the activation energy for power law creep is Q ≈ 80 KJ mole -1 (Goodman et al, 1981). This implies a creep power of n = 8x10 4 (714)(8.3) = 13.5 (19) This is significantly higher than n ≈ 3 observed at stresses below 1MPa.…”

Section: The Apparent Coefficient Of Friction Of Frozen Cracksmentioning

confidence: 76%

“…This implies a creep power of n = 8x10 4 (714)(8.3) = 13.5 (19) This is significantly higher than n ≈ 3 observed at stresses below 1MPa. However, n for ice is observed to rise rapidly at stresses above 1 MPa (Goodman et al, 1981), so this may simply reflect a higher flow stress on the asperities.…”

Section: The Apparent Coefficient Of Friction Of Frozen Cracksmentioning

confidence: 99%

“…There is a poorly understood change in activation energy at about −10°C thought to be associated with the suppression of pressure melting at grain boundaries below this temperature (Goodman et al, 1981;Duval et al, 1983). We will take the analysis in this paper one step further by assuming a generic form for this high temperature power-law flow in ice, the strain rate Ý ε is given by…”

Section: The Apparent Coefficient Of Friction Of Frozen Cracksmentioning

confidence: 99%

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Generation of High Frequency P and S Wave Energy by Rock Fracture During a Buried Explosion

Sammis¹,

Rosakis²

2007

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. (From -To) REPORT DATE 10-11-2007 REPORT TYPE Final Report DATES COVERED SPONSOR/MONITOR'S ACRONYM(S)AFRL/RVBYE SPONSOR/MONITOR'S REPORT NUMBER(S) AFRL-RV-HA-TR-2007-1132 DISTRIBUTION / AVAILABILITY STATEMENTApproved for Public Release; Distribution Unlimited. SUPPLEMENTARY NOTES ABSTRACTThe micromechanical damage mechanics developed by Ashby and Sammis (1990) was used to explore the effects of rock fracture on the seismic coupling of explosions. An important focus was the effect of ice in the fractures. The main effect of ice in the cracks of crystalline rock is to bridge the existing cracks forming a larger number of smaller cracks. Ice also increases the coefficient of friction on the cracks resulting in a significant increase in both elastic stiffness and fracture strength, both of which are temperature and strain-rate dependent. The damage mechanics model was used to interpret laboratory data on frozen rock and a field experiment in which chemical explosions were detonated above and below the permafrost layer in Alaska to directly observe the effect of ice in rock on the seismic coupling. Finally, we used the "equivalent elastic medium model" for an explosive source developed by Johnson and Sammis (2001) to explore the effect of an increase in both elastic stiffness and compressive strength on the amplitude of far-field seismic radiation. Our conclusion is that an explosion in frozen rock should have a smaller apparent yield than the same explosion in rock at temperatures above the freezing point and that the effect should be larger in limestone than in granite.

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“…12 shows that Qf, could be greater than the creep activation energy, Q, involving no cracks and furthermore could depend on stress and temperature. It must be pointed out that the numerical value for Q I assumed here is not different from the activation energy for self-diffusion [22, 5 1, 521, although creep in ice may not be diffusion-controlled but glide-controlled [53], and was determined by Sinha [32] for the range -44 to In discussing the activation ehergy for steadystate, or rather minimum, creep rate of polycrystalline ice experimentally determined high values above -10" C (0.96 T, ) were treated by Weertman [5 11 as unrealistic. Examinations of experimental conditions used, for example, by Glen [54] and Barnes etal.…”

Section: Discussionmentioning

confidence: 99%

Intercrystalline cracking, grain-boundary sliding, and delayed elasticity at high temperatures

Sinha

1984

J Mater Sci

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/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. Science, 19, pp. 359-76, 1984 Intercrystalline cracking, grain-boundary sliding, and delayed elasticity at high temperatures Sinha, N. K. Journal of Materials Journal of Materials Science is published monthly byChapman and Hall Ltd., 11 New Fetter Lane, London EC4P 4EE, from whom subscription details are available. 19 (1984) 359-376 Intercrystalline cracking, grain-boundary sliding, and delayed elasticity at high temperatures NIRMAL K. SINHA Division of Building Research, National Research Council of Canada, Ottawa, Canada JOURNAL OF MATERIALS SCIENCEThe hypothesis of an interrelation between grain-boundary sliding and delayed elasticity in polycrystalline materials at high homologous temperatures is used to investigate the conditions conducive to microcracking. It is known that a material may exhibit cracking activity on attaining a critical delayed-elastic strain corresponding to a critical grainboundary sliding displacement. Experimental data on ice at temperatures > 0.9 T, are used to verify this concept. The new criterion is then extended to develop simple, selfconsistent equations describing the interdependence of stress, strain, time, temperature, and grain size in predicting the onset of structural degradation due to microcracking and hence possible failure by fracture or rupture. The merit of the theory lies in its ability to forecast explicitly a large number of commonly observed high-temperature phenomena, including superplasticity, brittle-ductile transition, and the stress and temperature dependence of the apparent activation energy for fracture. One derivation makes it clear that cracking occurs when a critical stress depending only on temperature (and independent of grain size) is exceeded. The near constancy of fracture strain in the quasi brittle range can also be predicted

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The plasticity of polycrystalline ice

Cited by 107 publications

References 52 publications

Crack-enhanced creep in polycrystalline material: strain-rate sensitive strength and deformation of ice

Crack-enhanced creep in polycrystalline material: strain-rate sensitive strength and deformation of ice

Generation of High Frequency P and S Wave Energy by Rock Fracture During a Buried Explosion

Intercrystalline cracking, grain-boundary sliding, and delayed elasticity at high temperatures

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