Uniaxial Constant Compressive Stress Creep Tests on Sea Ice

1995 ◽  
Vol 117 (4) ◽  
pp. 283-289 ◽  
Author(s):  
N. K. Sinha ◽  
C. Zhan ◽  
E. Evgin

First-year columnar-grained sea ice from Resolute Passage (74° 42′ N, 94° 50′ W), off Barrow Strait in the Canadian High Arctic, was tested under constant uniaxial compressive stress applied normal to the length of the columns. Creep tests were performed at 263 K, 253 K, and 243 K in the stress range of 0.7 to 2.5 MPa, using prismatic samples with dimensions of 50 mm × 100 mm × 250 mm. Because three-dimensional creep data are extremely useful for developing constitutive equations, axial strain was measured in conjunction with the measurements of two lateral strains and acoustic emissions. The deformations were measured using displacement gages mounted on the samples. A description of the experimental procedures and the observations are presented here. One-to-one correspondence has been obtained between the present results on the dependence of minimum creep rate on stress and previous data on the dependence of uniaxial compressive strength on strain rate under constant strain rate. The strain-rate sensitivity of compressive strength can, therefore, be obtained from creep tests which can be performed by using simple dead-load test systems.

1984 ◽  
Vol 11 (1) ◽  
pp. 82-91 ◽  
Author(s):  
N. K. Sinha

Strain-rate and stress-rate sensitivity of the compressive strength of first-year columnar-grained ice, first-year congealed frazil ice, and columnar-grained ice from an old floe have been investigated with load applied in the horizontal plane. In spite of similar salinity and density, the frazil ice proved to be considerably stronger than the columnar-grained ice. The strength of porous old floe ice with columnar-grained structure was very much the same as that of first-year ice of similar structure, but the clear bulk ice of the old floe was strongest. Rate sensitivity of strength for the three types of saline ice was similar to that of fresh-water ice. Ductility of the old clear ice (as measured by the strain at upper yield) was the same as that of fresh-water ice; ductility of porous old ice was comparable to that of new frazil ice. New columnar-grained ice proved to be the most ductile material. Key words: columnar-grained, compressive strength, ductility, first-year, frazil, multi-year, rate sensitivity, sea ice.


1993 ◽  
Vol 115 (2) ◽  
pp. 200-203 ◽  
Author(s):  
Z. Xia ◽  
F. Ellyin

Constant strain-rate plastic straining followed by creep tests were conducted to investigate the effect of prior plastic straining on the subsequent creep behavior of 304 stainless steel at room temperature. The effects of plastic strain and plastic strain-rate were delineated by a specially designed test procedure, and it is found that both factors have a strong influence on the subsequent creep deformation. A creep model combining the two factors is then developed. The predictions of the model are in good agreement with the test results.


1969 ◽  
Vol 8 (54) ◽  
pp. 463-473 ◽  
Author(s):  
S. J. Jones ◽  
J. W. Glen

AbstractResults obtained from tensile and compressive tests on pure ice single crystals at various temperatures down to −90°C are reported. At −50°C tensile creep tests give a continually increasing creep rate until fracture, as observed at higher temperatures. The stress dependence of the strain-rate is discussed. Fracture stress increases with decreasing temperature. Results from constant strain-rate compressive tests are compared with theoretical curves computed from Johnston’s (1962) theory of dislocation multiplication. A dislocation velocity of the order of 0.5×10−8 m s−1 is deduced for ice at −50°C.


1972 ◽  
Vol 94 (1) ◽  
pp. 207-212 ◽  
Author(s):  
D. P. Kendall

The effect of elastic strain rates ranging from 10−14 to 10 sec−1 and temperatures ranging from 200 K (−100 F) to 590 K (600 F) on the yield strength of several steels is reported. The steels utilized are a 1018 mild steel, 4340 steel, H-11 tool steel, and 300 grade maraging steel. The results are interpreted in terms of the Cottrell-Bilby yielding model based on release of dislocations from locking carbon atmospheres. The results for all of the materials except the maraging steel are consistent with this model if it is modified to account for relocking of dislocations by migration of carbon atoms. The maraging steel shows a constant strain rate sensitivity at a constant temperature, over the range of strain rates investigated. This rate sensitivity decreases with increasing temperature and at 590 K (600 F) a decreasing strength with increasing strain rate is found. This is attributed to stress aging effects.


2000 ◽  
Vol 653 ◽  
Author(s):  
X. M. Gu ◽  
Y. Q. Sun

AbstractThe discontinuous yielding of a model material, which contains an edge dislocation moving in the atmosphere of solute atoms, is studied by Kinetic Monte Carlo (KMC) simulations. The stress-strain curves for a constant strain rate were obtained at different temperatures. The dislocation moves discontinuously, producing three types of serrated yielding behavior at intermediate temperatures for different imposed strain rates. Positive dependence of flow stress on temperature and negative strain rate sensitivity were observed in the regime of discontinuous motion. The present model, though highly simplified and not taking into account the collective behaviors of dislocations in real materials, does exhibit some of the basic features observed in experiments.


2000 ◽  
Vol 46 (152) ◽  
pp. 41-44 ◽  
Author(s):  
Y. L. Trickett ◽  
I. Baker ◽  
P. M. S. Pradhan

AbstractSingle crystals with a wide variety of orientations were cut from large pucks of laboratory-grown ice. Constant-strain-rate compression tests were performed on the crystals either at an axial strain rate of 1 × 10−5 s−1at –20°C or at axial strain rates from 1 × 10−6 s−1 to 1 × 10−4 s−1 at –10°C. In agreement with previous studies of ice flow, the compression tests showed a linearly rising stress with increasing strain, followed by a sharply declining stress after reaching a peak. With further strain, the sharp decline in stress slowed and the flow stress approached a plateau that was only weakly dependent on strain. For all crystallographic orientations, it was found that Schmid’s (critical resolved shear stress) law was obeyed by the peak stress. Slip lines clearly showed that basal slip was the deformation mode.


2016 ◽  
Vol 32 (6) ◽  
pp. 717-724 ◽  
Author(s):  
W. Wu ◽  
F. Qin ◽  
T. An ◽  
P. Chen

AbstractThrough-Silicon-Via (TSV) is considered to be the most potential solution for 3D electronic packaging, and the mechanical properties of TSV-Cu are critical for TSV reliability improving. In this paper, to make deeply understand the creep behavior of TSV-Cu, nanoindentation creep tests were conducted to obtain its creep parameters. At first, the TSV specimens were fabricated by means of a typical TSV manufacturing process. Then a combination programmable procedure of the constant indentation strain rate method and the constant load method was employed to study the creep behavior of TSV-Cu. To understand the influence of the previous loading schemes, including the different values of the indentation strain and the maximum depths, the nanoindentation creep tests under different loading conditions were conducted. The values of creep strain rate sensitivity m were derived from the corresponding displacement-holding time curves, and the mean value of m finally determined was 0.0149. The value of m is considered no obvious correlation with the different indentation strain rates and the maximum depths by this method. Furthermore, the mechanism for the room temperature creep was also discussed, and the grain boundaries might play an significant role in this creep behavior.


2000 ◽  
Vol 643 ◽  
Author(s):  
Jan Fikar ◽  
Joël Bonneville ◽  
Nadine Baluc ◽  
Pierre Guyot

AbstractIcosahedral AlCuFe poly-quasicrystalline specimens were deformed in constant strain rate compression tests at temperatures ranging between 300K - 1020K. Below nearly 0.7 Tm (Tm is the melting temperature) the specimens were brittle. Above the brittle-to-ductile transition temperature, after the elastic stage the stress-strain curves exhibit a marked yield-point followed by a stage of strain softening only. Transient creep tests were performed at different given stress/strain levels after interrupting the constant strain-rate deformation tests. After the transient tests, the flow strength of the specimens was investigated anew at constant strain rate. The results are interpreted in the framework of a dislocation model, where two effects opposing dislocation movement are considered: firstly, the usual elastic dislocation interaction, yielding a work-hardening contribution, and, secondly, a friction stress specific to the quasiperiodic lattice, leading to a softening effect.


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