scholarly journals Downdrag Loads Developed by a Floating Ice Cover: Field Experiments

1974 ◽  
Vol 11 (3) ◽  
pp. 339-347 ◽  
Author(s):  
R. Frederking
Keyword(s):  
Shear Stress ◽  
Steady State ◽  
Field Experiments ◽  
Ice Cover ◽  
Steady State Creep ◽  
Displacement Rate ◽  
Efficient Design ◽  
Shear Creep ◽  
Creep Characteristics ◽  
Applied Shear Stress

The first phase of an investigation of the vertical forces developed on a structure by a floating ice cover frozen to it is described. It is the objective of this work to develop the theoretical, experimental, and field aspects of vertically acting loads required for the more efficient design of structures subject to such loads. A load frame was constructed that would apply constant upward acting loads to wooden piles frozen into an ice cover composed mainly of snow ice. Load, ice temperatures, and movement of the pile in relation to the ice were measured.The time-dependent movement of the pile in relation to the ice exhibited creep characteristics, and these results were related to shear creep for grouted rod anchors in permafrost. Results of a previous study for WF steel H-beams in ice were also considered. The steady-state creep displacement rate for wooden piles in ice, rod anchors in permafrost, and WF steel H-beams in ice exhibited a comparable dependence on the constant applied shear stress. The steady-state creep displacement rate of a 100-mm wooden pile in snow ice at −3 °C and under a constant applied shear stress of 180 kN/m2 was about 1 mm/day.

Study on Thermal Cycling of Sn0.7Cu Solder

2013 ◽  
Vol 791-793 ◽  
pp. 362-365
Author(s):  
Li Yang ◽  
Ju Li Li ◽  
Jing Guo Ge ◽  
Meng Li ◽  
Nan Ji
Keyword(s):  
Shear Stress ◽  
Steady State ◽  
High Temperature ◽  
Thermal Cycling ◽  
Shear Strain ◽  
Maximum Shear Stress ◽  
Steady State Creep ◽  
Maximum Shear Strain ◽  
Cycle Number ◽  
State Cycle

Thermal cycling of a unit Sn0.7Cu solder was studied based on the steady-state creep constitutive equation and Matlab software. The results show that there is a steady-state cycle for the thermal cycling of unit Sn0.7Cu eutectic solder. In steady-state thermal cycling, the shear stress is increased with the increase of temperature. There is a stage of stress relaxation during high temperature. A liner relationship between maximum shear stress and maximum shear strain is observed during thermal cycling. The metastable cycle number is declined greatly with the increase of maximum shear strain.

Experimental Study on Direct Shear Creep Characteristics and Long-Term Strength of Red Layer Sliding Zone Soil in Southern Hunan

2013 ◽  
Vol 842 ◽  
pp. 782-787 ◽  
Author(s):  
Feng Zhu ◽  
Zhong Yuan Duan ◽  
Zhen Yu Wu ◽  
Yu Qi Wu ◽  
Tian Long Li ◽  
...  
Keyword(s):  
Shear Stress ◽  
Term Strength ◽  
Direct Shear ◽  
Creep Tests ◽  
Shear Creep ◽  
Creep Characteristics ◽  
Southern Hunan ◽  
Sliding Soil ◽  
Sliding Zone

The creep characteristics of red layer sliding soil under the condition of different vertical loads and water contents were studied through a series of direct shear creep tests. Tests results showed that the water infiltrated to the sliding zone along the fissure of red layer sliding belt due to the crush of red layer sliding rock, leading to softening of sliding zone and acceleration of shear creep. When the shear stress reached the limit of long-term shear strength, sliding soil was broken suddenly with small vertical loads (50 kPa and 100kPa), while the sliding soil presented as a constant acceleration creep with enough vertical loads (200 kPa and 300 kPa). The inflection point in shear stress-shear displacement isochronous curve corresponded to the long-term strength of the soil.

State and Rate Dependent Friction Laws for Modeling High-Speed Frictional Slip at Metal-on-Metal Interfaces

2006 ◽  
Vol 129 (1) ◽  
pp. 17-22 ◽  
Author(s):  
Hamid Ullah ◽  
M. A. Irfan ◽  
V. Prakash
Keyword(s):  
Shear Stress ◽  
Steady State ◽  
High Speed ◽  
Friction Stress ◽  
Normal Pressure ◽  
Friction Model ◽  
Friction Laws ◽  
Rate Dependent ◽  
Applied Shear Stress ◽  
Slip Event

In the present paper the applicability of state and rate dependent friction laws in describing the phenomena of high speed slip at metal-on-metal interfaces is investigated. For the purpose of model validation, results of plate-impact pressure-shear friction experiments were conducted by Irfan in 1998 and Irfan and Prakash in 2000 using a Ti6Al4V and Carpenter Hampden tool-steel tribo pair are employed. In these experiments high normal pressures (1-3GPa) and slip speeds of approximately 50m∕s were attained during the high-speed slip event. Moreover, these experiments were designed to investigate the evolution of friction stress in response to step changes in normal pressure and also in the applied shear stress during the high-speed slip event. A step drop in normal pressure is observed to result in an exponential decay of the friction stress to a new steady-state characteristic of the current normal pressure and the current slip velocity. A step drop in applied shear stress is observed to lead to an initial drop in friction stress, which later increases toward a new steady-state friction stress level. In response to the step drop in applied shear stress the slip velocity initially increases and then decreases to a new steady-state level consistent with the new friction stress level. A modified rate and state dependent friction model that employs both velocity and normal stress dependent state variables is used to simulate the experimental results. A good correlation is found between the experimental results and the predictions of the proposed state and rate dependent friction model.

scholarly journals Transversely Isotropic Creep Characteristics and Damage Mechanism of Layered Phyllite Under Uniaxial Compression Creep Test

2021 ◽  
Author(s):  
Jiabing Zhang ◽  
Xiaohu Zhang ◽  
Zhen Huang ◽  
Helin Fu
Keyword(s):  
Steady State ◽  
Uniaxial Compression ◽  
Creep Deformation ◽  
Transversely Isotropic ◽  
Damage Mechanism ◽  
Steady State Creep ◽  
Creep Stage ◽  
Compression Creep ◽  
Bedding Angle ◽  
Creep Characteristics

Abstract The layered surrounding rocks of deep tunnels undergo large creep deformation due to the presence of planes of weakness and the presence of prolonged high in-situ stress, thereby the deformation severely endangers the safety of tunnels. This study conducts uniaxial compression creep tests to experimentally investigate the transversely isotropic creep characteristics and the damage mechanism of layered phyllite samples having bedding angles of 0°, 22.5°, 45°, 67.5°, and 90°. The results indicate that the creep deformation of the specimens takes place in four stages: the instantaneous elastic deformation stage, the deceleration creep stage, the steady-state creep stage, and the accelerated creep stage. The cumulative creep deformation and the creep time during the steady-state creep stage of the specimens initially decrease and then increase as the bedding angle changes from 0° to 90°, thereby, corresponding to the initial increase and subsequent decrease in creep rate during the deceleration creep stage. Based on the existing viscoelastic-plastic damage creep model, the creep parameters E1, E2, η2, and η3 are observed to initially decrease and then increase with the increase in bedding angle, hence demonstrating that the creep characteristics and damage mechanism of the layered rock mass are controlled by the effect of the natural weakness planes and show significant transversely isotropic characteristics.

Effect of Zn addition on steady state creep characteristics of Sn–3·3Ag solder alloy

2008 ◽  
Vol 24 (4) ◽  
pp. 488-494 ◽  
Author(s):  
A. Fawzy ◽  
N. Habib ◽  
M. Sobhy ◽  
E. Nassr ◽  
G. Saad
Keyword(s):  
Steady State ◽  
Solder Alloy ◽  
Steady State Creep ◽  
Zn Addition ◽  
Creep Characteristics
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