scholarly journals The effect of grain size on deformation and failure of copper under dynamic loading

1994 ◽  
Vol 04 (C8) ◽  
pp. C8-195-C8-199
Author(s):  
D. H. Lassila ◽  
M. M. LeBlanc ◽  
F. H. Magness
Keyword(s):  
Grain Size ◽  
Dynamic Loading ◽  
Deformation And Failure

Dissipation Pattern of Excess Pore Pressure After Liquefaction in Saturated Sand Deposits

2003 ◽  
Vol 1821 (1) ◽  
pp. 59-67 ◽  
Author(s):  
Ik Soo Ha ◽  
Young Ho Park ◽  
Myoung Mo Kim
Keyword(s):  
Grain Size ◽  
Pore Pressure ◽  
Dynamic Loading ◽  
Time History ◽  
Excess Pore Pressure ◽  
Pore Pressures ◽  
Dissipation Pattern ◽  
Effective Grain Size ◽  
Coefficient Of Uniformity ◽  
Excess Pore

In liquefied areas, the amount of damage to a structure is mainly affected by the postliquefaction behavior of the liquefied ground. Understanding postliquefaction behavior requires understanding the dissipation pattern of excess pore pressure after liquefaction. It is difficult to measure pore pressures generated and dissipated during an earthquake because of the more-or-less randomness of earthquake events. Researchers have artificially generated liquefaction with sand samples in the laboratory and have simulated curves for the time history dissipation of excess pore pressure. To estimate variation in permeability during dynamic loading, which should be known for settlement predictions of the ground undergoing liquefaction, 1-g shaking table tests were carried out on five kinds of sands, all with high liquefaction potentials. During tests, excess pore pressures at various depths and surface settlements were measured. The measured curve of the excess pore pressure dissipation was simulated using the solidification theory. From analysis of the velocity of dissipation, the dissipation pattern of excess pore pressure after liquefaction was examined. Permeability during dissipation was calculated using the measured settlement and dissipation velocity, also used for estimating permeability during dynamic loading. The dissipation velocity of excess pore pressure after liquefaction had a linear correlation with the effective grain size divided by the coefficient of uniformity. The increase in the ground’s initial relative density played a role in shifting this correlation curve toward increased dissipation velocity. Permeability during liquefaction increased 1.4 to 5 times compared with the permeability of the original ground, the increase becoming greater as the effective grain size of the test sand increased and the coefficient of uniformity decreased.

Atomistic Study of Deformation and Failure Behavior in Nanocrystalline Mg

MRS Advances ◽  
2016 ◽  
Vol 1 (58) ◽  
pp. 3859-3864 ◽  
Author(s):  
Garvit Agarwal ◽  
Gabriel Paun ◽  
Ramakrishna R. Valisetty ◽  
Raju Namburu ◽  
Arunachalam M. Rajendran ◽  
...  
Keyword(s):  
Grain Size ◽  
Large Scale ◽  
Md Simulations ◽  
Uniaxial Tensile ◽  
Failure Behavior ◽  
Deformation And Failure ◽  
Uniaxial Tensile Stress ◽  
Atomistic Study ◽  
Eam Potential ◽  
Critical Grain Size

ABSTRACTLarge scale molecular dynamics (MD) simulations are carried out to investigate the failure response of nanocrystalline Mg using the EAM potential under conditions of uniaxial tensile stress and uniaxial tensile strain loading. The MD simulations are carried out at a strain rate of 109s-1 for grain sizes in the range of 10 nm to 30 nm. The effect of grain size on the strength of the metal is investigated and the critical grain size for transition to inverse Hall-Petch regime is identified.

scholarly journals Deformation Caused by Dynamic Load and Support Requirements in a Deep Gob-Side Entry Rock Mass

2019 ◽  
Vol 2019 ◽  
pp. 1-16
Author(s):  
Yandong Zhang ◽  
Yongjie Yang ◽  
Changhua Zhuge
Keyword(s):  
Dynamic Loading ◽  
Dynamic Load ◽  
Rock Properties ◽  
Optimized Design ◽  
Deformation Characteristics ◽  
Test Results ◽  
Support Design ◽  
Deformation And Failure ◽  
Ground Support ◽  
Bolt Support

Gob-side entries in deep coal mines can be subjected to dynamic loading when driving along the goaf. The effects of this dynamic loading and improved ground support requirements are investigated in the Gaojiabao Coal Mine, China. Numerical modeling is first used to simulate the deformation characteristics of rock surrounding the gob-side entry under dynamic load with the original support design. Dynamic loading in this scenario causes continual deterioration in rock properties, and deformation accumulates as the number of dynamic loads increases. Therefore, the overall strength and rigidity of the bolt support design need improvement, especially in terms of using yielding bolts that assist in releasing unnecessary support loads. The deformation characteristics of the rock surrounding the gob-side entry are combined with the concept of coupled pressure support to provide an optimized bolt support design. The support effects of the optimized design are then also numerically simulated and compared with the original support design. Deformation in the optimized design is significantly reduced, and roadway control is improved. Finally, the optimized design is applied and measured in a gob-side entry excavation. The field test results show that the potential for loosening, deformation, and failure of the surrounding rock is effectively controlled.

Dynamic instability of seasonally thawing silty soils

1994 ◽  
Vol 31 (3) ◽  
pp. 454-462
Author(s):  
Eugene A. Voznesensky ◽  
Vladimir Y. Kalachev ◽  
Victor T. Trofimov ◽  
Victoria V. Kostomarova
Keyword(s):  
Grain Size ◽  
Dynamic Loading ◽  
Laboratory Experiments ◽  
Dynamic Behaviour ◽  
Dynamic Instability ◽  
Dynamic Properties ◽  
Clayey Soils ◽  
Mining Equipment ◽  
Silty Soils ◽  
Key Words Dynamic

The peculiarities of the dynamic behaviour of silty soils in laboratory experiments that simulate their interaction with gas mining equipment are analyzed. These seasonally thawing soils appear to be very sensitive to dynamic loading and sometimes even liquefaction. Several peculiarities of their dynamic behaviour include: (i) their special sensitivity to very definite and narrow vibration frequency ranges, which vary with grain size and moisture content, and result from the resonant effects in the soil; (ii) the redistribution of pore water during the vibration and subsequent regain; (iii) the thixotropic recovery of the soil after vibration, resulting in the regain of its strength over initial levels, water content and density being constant. Both dilatant and thixotropic effects take place in such soils during dynamic loading, distinguishing them from both clean sands and clayey soils. On the basis of the peculiarities of dynamic behaviour discussed, the authors consider such soils as dilatantly thixotropic dispersed systems. Key words : dynamic properties, soils, thixotropy, liquefaction, resonance, silts.

The Effect of Grain Size on Deformation and Failure of Ti2AlC MAX Phase under Thermo-Mechanical Loading

2017 ◽  
Vol 57 (5) ◽  
pp. 675-685 ◽  
Author(s):  
P. Naik Parrikar ◽  
R. Benitez ◽  
H. Gao ◽  
M. Radovic ◽  
A. Shukla
Keyword(s):  
Grain Size ◽  
Mechanical Loading ◽  
Max Phase ◽  
Deformation And Failure

scholarly journals Failure Mechanisms of Alloys with a Bimodal Graine Size Distribution

2020 ◽  
pp. 521-534
Author(s):  
Vladimir A. Skripnyak ◽  
Evgeniya G. Skripnyak ◽  
Vladimir V. Skripnyak
Keyword(s):  
Grain Size ◽  
Titanium Alloys ◽  
Size Distribution ◽  
Dynamic Loading ◽  
Grain Size Distribution ◽  
High Strain ◽  
Fine Grained ◽  
Localization Of Plastic Deformation ◽  
Grain Size Distributions ◽  
Bimodal Grain Size

AbstractA multi-scale computational approach was used for the investigation of a high strain rate deformation and fracture of magnesium and titanium alloys with a bimodal distribution of grain sizes under dynamic loading. The processes of inelastic deformation and damage of titanium alloys were investigated at the mesoscale level by the numerical simulation method. It was shown that localization of plastic deformation under tension at high strain rates depends on grain size distribution. The critical fracture stress of alloys depends on relative volumes of coarse grains in representative volume. Microcracks nucleation at quasi-static and dynamic loading is associated with strain localization in ultra-fine grained partial volumes. Microcracks arise in the vicinity of coarse and ultrafine grains boundaries. It is revealed that the occurrence of a bimodal grain size distributions causes increased ductility, but decreased tensile strength of UFG alloys. The increase in fine precipitation concentration results not only strengthening but also an increase in ductility of UFG alloys with bimodal grain size distribution.

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