Grain Size and the Compressive Strength of Ice

1985 ◽  
Vol 107 (3) ◽  
pp. 369-374 ◽  
Author(s):  
D. M. Cole
Keyword(s):  
Grain Size ◽  
Size Effect ◽  
Strain Rate ◽  
Peak Stress ◽  
Applied Strain ◽  
Test Material ◽  
Strain Rates ◽  
Grain Size Effect ◽  
Compression Tests ◽  
Polycrystalline Ice

This work presents the results of uniaxial compression tests on freshwater polycrystalline ice. Grain size of the test material ranged from 1.5 to 5 mm, strain rate ranged from 10−6 to 10−2 s−1 and the temperature was −5°C. The grain size effect emerged clearly as the strain rate increased to 10−5 s−1 and persisted to the highest applied strain rates. On average, the stated increase in grain size brought about a decrease in peak stress of approximately 31 percent. The occurrence of the grain size effect coincided with the onset of visible cracking. The strength of the material increased to a maximum at a strain rate of 10−3 s−1, and then dropped somewhat as the strain rate increased further to 10−2 s−1. Strain at peak stress generally tended to decrease with both increasing grain size and increasing strain rate. The results are discussed in terms of the deformational mechanisms which lead to the observed behavior.

scholarly journals Strain-Rate and Grain‒Size Effects in Ice

1987 ◽  
Vol 33 (115) ◽  
pp. 274-280 ◽  
Author(s):  
David M. Cole
Keyword(s):  
Grain Size ◽  
Strain Rate ◽  
Transition Point ◽  
Boundary Migration ◽  
Peak Stress ◽  
Strain Rates ◽  
Thin Sections ◽  
Fine Grained ◽  
Lower Strain ◽  
Polycrystalline Ice

AbstractThis paper presents and discusses the results of constant deformation-rate tests on laboratory-prepared polycrystalline ice. Strain-rates ranged from 10−7to 10−1s−1, grain–size ranged from 1.5 to 5.8 mm, and the test temperature was −5°C.At strain-rates between 10−7and 10−3s−1, the stress-strain-rate relationship followed a power law with an exponent ofn= 4.3 calculated without regard to grain-size. However, a reversal in the grain-size effect was observed: below a transition point near 4 × 10−6s−1the peak stress increased with increasing grain-size, while above the transition point the peak stress decreased with increasing grain-size. This latter trend persisted to the highest strain-rates observed. At strain-rates above 10−3s−1the peak stress became independent of strain-rate.The unusual trends exhibited at the lower strain-rates are attributed to the influence of the grain-size on the balance of the operative deformation mechanisms. Dynamic recrystallization appears to intervene in the case of the finer-grained material and serves to lower the peak stress. At comparable strain-rates, however, the large-grained material still experiences internal micro-fracturing, and thin sections reveal extensive deformation in the grain-boundary regions that is quite unlike the appearance of the strain-induced boundary migration characteristic of the fine-grained material.

scholarly journals Strain-Rate and Grain‒Size Effects in Ice

1987 ◽  
Vol 33 (115) ◽  
pp. 274-280 ◽  
Author(s):  
David M. Cole
Keyword(s):  
Grain Size ◽  
Strain Rate ◽  
Transition Point ◽  
Boundary Migration ◽  
Peak Stress ◽  
Strain Rates ◽  
Thin Sections ◽  
Fine Grained ◽  
Lower Strain ◽  
Polycrystalline Ice

AbstractThis paper presents and discusses the results of constant deformation-rate tests on laboratory-prepared polycrystalline ice. Strain-rates ranged from 10−7 to 10−1s−1, grain–size ranged from 1.5 to 5.8 mm, and the test temperature was −5°C.At strain-rates between 10−7 and 10−3 s−1, the stress-strain-rate relationship followed a power law with an exponent of n = 4.3 calculated without regard to grain-size. However, a reversal in the grain-size effect was observed: below a transition point near 4 × 10−6 s−1 the peak stress increased with increasing grain-size, while above the transition point the peak stress decreased with increasing grain-size. This latter trend persisted to the highest strain-rates observed. At strain-rates above 10−3 s−1 the peak stress became independent of strain-rate.The unusual trends exhibited at the lower strain-rates are attributed to the influence of the grain-size on the balance of the operative deformation mechanisms. Dynamic recrystallization appears to intervene in the case of the finer-grained material and serves to lower the peak stress. At comparable strain-rates, however, the large-grained material still experiences internal micro-fracturing, and thin sections reveal extensive deformation in the grain-boundary regions that is quite unlike the appearance of the strain-induced boundary migration characteristic of the fine-grained material.

scholarly journals The effects of Ca++ on the strength of polycrystalline ice

2016 ◽  
Vol 62 (235) ◽  
pp. 954-962 ◽  
Author(s):  
KEVIN HAMMONDS ◽  
IAN BAKER
Keyword(s):  
Strain Rate ◽  
Microstructural Analysis ◽  
Constant Load ◽  
Applied Strain ◽  
Strain Rates ◽  
Compression Tests ◽  
Polycrystalline Ice ◽  
Post Test ◽  
The Mean ◽  
Deformation Tests

ABSTRACTRecent studies have suggested a physical link between Ca++ ions and an increase in the ductility or ‘softening’ of polycrystalline ice. In order to investigate the potential effects of Ca++ on deformation, we created sets of both undoped and CaSO4-doped specimens of polycrystalline ice for testing in uniaxial tension or compression. Deformation tests in tension were carried out under a constant load at an initial stress of 0.75 MPa and a temperature of −6°C. Compression tests were carried out at −10 and −20°C at constant strain rates of 1×10−4 s−1, 1 × 10−5 s−1 and 1 × 10−6 s−1 and taken to 5% strain. Our results show that CaSO4 increases the strength of polycrystalline ice at higher strain rates and lower temperatures, an effect that decreases with decreasing strain rate and higher temperatures. A microstructural analysis of the post-test compression specimens reveals mean grain diameters much larger in the CaSO4-doped specimens tested at the lowest applied strain rate of 1 × 10−6 s−1. Precipitates were found to have formed along grain boundaries in some doped specimens and evidence of intergranular fracture was observed in all specimens tested at 1 × 10−4 and 1 × 10−5 s−1. In tension-tested specimens, there was no difference in the mean grain diameter between doped and undoped specimens at 25% strain.

scholarly journals Mechanical Properties of Dye 3 Greenland Deep Ice Cores

1984 ◽  
Vol 5 ◽  
pp. 1-8 ◽  
Author(s):  
Nobuhiko Azuma ◽  
Akira Higashi
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Power Law ◽  
Ice Core ◽  
Ice Cores ◽  
Uniaxial Stress ◽  
Strain Rates ◽  
Compression Tests ◽  
Polycrystalline Ice ◽  
Relationship Of

Uniaxial compression tests were carried out with specimens cut from several deep ice cores obtained at Dye 3, Greenland, in 1980 and 1981. The power law relationship of = Αση was obtained between the uniaxial strain-rate and the uniaxial stress σ. In a range of strain-rates between 10−8 and 10−7 s−1, the value of the power n for samples with strong single maximum fabric was approximately 4, significantly larger than the value of 3 which has been generally accepted from experiments using artificial polycrystalline ice. A work-hardening effect was found in the ice-core samples taken from a depth of 1900 m, which had a smaller grain size than the others. Recrystallization occurred when the temperature of the specimen was raised during the test and this ultimately caused the formation of the so-called diamond pattern ice fabric.

scholarly journals Investigation on grain size effect in high strain rate ductility of 1100 pure aluminum

2017 ◽  
Author(s):  
N. Bonora ◽  
N. Bourne ◽  
A. Ruggiero ◽  
G. Iannitti ◽  
G. Testa
Keyword(s):  
Grain Size ◽  
Size Effect ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Pure Aluminum ◽  
Grain Size Effect

scholarly journals Dynamic Precipitation in Mg–8.08Gd–2.41Sm–0.30Zr Alloy during Hot Compression

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2147
Author(s):  
Limin Zhu ◽  
Quanan Li ◽  
Qing Zhang ◽  
Xiaoya Chen
Keyword(s):  
Grain Size ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Hot Compression ◽  
Strain Rates ◽  
Dynamic Precipitation ◽  
Compression Tests ◽  
Effects Of Temperature ◽  
Compression Temperature

Dynamic precipitation of Mg–8.08Gd–2.41Sm–0.30Zr (wt %) alloy during hot compression was studied in the present work. The effects of temperature and strain rate on dynamic precipitation, and the effects of dynamic precipitation on dynamic recrystallization (DRX) and microhardness, were systematically analyzed. For this purpose, hot compression tests were conducted at the strain rates of 0.002~1 s−1 and temperatures of 350~500 °C, with the compaction strain of 70% (εmax = 0.7). The obtained results revealed that dynamic precipitation occurred during hot compression at 350~400 °C, but did not occur for T ≥ 450 °C. The precipitates were demonstrated to be β-Mg5Gd with a size of 200~400 nm, and they were distributed in the DRXed region. Dynamic precipitation occurred at strain rates in the 0.002~0.01 s−1 range, but did not occur when the strain rates were in the 0.1~1 s−1 range for the hot compression temperature of 350 °C. The relationships between the hot compression temperature (T) and DRXed grain size (lnd), microhardness (Hv), and DRXed grain size (d−1/2) of Mg–8.08Gd–2.41Sm–0.30Zr alloy were obtained.

Fracture behavior of Inconel 718 sheet in thermal-aided deformation considering grain size effect and strain rate influence

2017 ◽  
Vol 130 ◽  
pp. 413-425 ◽  
Author(s):  
R. Zhao ◽  
X.J. Li ◽  
M. Wan ◽  
J.Q. Han ◽  
B. Meng ◽  
...  
Keyword(s):  
Grain Size ◽  
Size Effect ◽  
Strain Rate ◽  
Inconel 718 ◽  
Fracture Behavior ◽  
Grain Size Effect

Mechanical Properties of Dye 3 Greenland Deep Ice Cores

1984 ◽  
Vol 5 ◽  
pp. 1-8 ◽  
Author(s):  
Nobuhiko Azuma ◽  
Akira Higashi
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Power Law ◽  
Ice Core ◽  
Ice Cores ◽  
Uniaxial Stress ◽  
Strain Rates ◽  
Compression Tests ◽  
Polycrystalline Ice ◽  
Relationship Of

Uniaxial compression tests were carried out with specimens cut from several deep ice cores obtained at Dye 3, Greenland, in 1980 and 1981. The power law relationship of= Ασηwas obtained between the uniaxial strain-rateand the uniaxial stress σ. In a range of strain-rates between 10−8and 10−7s−1, the value of the power n for samples with strong single maximum fabric was approximately 4, significantly larger than the value of 3 which has been generally accepted from experiments using artificial polycrystalline ice. A work-hardening effect was found in the ice-core samples taken from a depth of 1900 m, which had a smaller grain size than the others. Recrystallization occurred when the temperature of the specimen was raised during the test and this ultimately caused the formation of the so-called diamond pattern ice fabric.

scholarly journals Densification strain rate in sintering of Tho2 and ThO2-0.25% Nb2O5 pellets

2009 ◽  
Vol 41 (2) ◽  
pp. 103-115 ◽  
Author(s):  
T.R.G. Kutty ◽  
K.B. Khan ◽  
A. Kumar ◽  
H.S. Kamath
Keyword(s):  
Grain Size ◽  
High Temperature ◽  
Size Effect ◽  
Strain Rate ◽  
Fold Increase ◽  
Grain Size Effect ◽  
Density Range ◽  
Densification Behavior ◽  
Drastic Increase ◽  
Powder Compacts

The densification behavior of ThO2 and ThO2 containing 0.25%Nb2O5 powder compacts was studied with the help of a high temperature push-rod type dilatometer. From the temperature versus density plots, densification strain rate, (1/?)(d?/dt), were calculated. It was observed that the addition of Nb2O5 to ThO2 has caused a drastic increase in densification strain rate in the density range of 76 to 82% of T.D. A five-fold increase in the values of strain rate for ThO2-0.25%Nb2O5 in comparison to pure ThO2 was observed in the temperature range of 1300 to 1350oC. The decrease in the densification strain rate for ThO2- 0.25% Nb2O5 (composition in wt%) at high densities may be attributed to the grain size effect.

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