scholarly journals Anisotropic modeling of layered rocks incorporating planes of weakness and volumetric stress

2019 ◽  
Vol 8 (3) ◽  
pp. 789-803 ◽  
Author(s):  
Shanchao Hu ◽  
Yunliang Tan ◽  
Hui Zhou ◽  
Wenkai Ru ◽  
Jianguo Ning ◽  
...  
Keyword(s):  
Volumetric Stress

Lattice-Boltzmann Simulation of Two-Phase Fluid Flows

1998 ◽  
Vol 09 (08) ◽  
pp. 1383-1391 ◽  
Author(s):  
Yu Chen ◽  
Shulong Teng ◽  
Takauki Shukuwa ◽  
Hirotada Ohashi
Keyword(s):  
Lattice Boltzmann ◽  
Fluid Flows ◽  
Navier Stokes ◽  
Interface Model ◽  
Two Phase ◽  
Navier Stokes Equation ◽  
Lattice Boltzmann Simulation ◽  
Dam Breaking ◽  
Volumetric Stress ◽  
Phase Fluid

A model with a volumetric stress tensor added to the Navier–Stokes Equation is used to study two-phase fluid flows. The implementation of such an interface model into the lattice-Boltzmann equation is derived from the continuous Boltzmann BGK equation with an external force term, by using the discrete coordinate method. Numerical simulations are carried out for phase separation and "dam breaking" phenomena.

The Effect of Hydrostatic Pressure on the Plastic Flow and Fracture of Metals

1964 ◽  
Vol 179 (1) ◽  
pp. 415-437 ◽  
Author(s):  
H. Ll. D. Pugh ◽  
D. Green
Keyword(s):  
Hydrostatic Pressure ◽  
Axial Stress ◽  
Strain Curve ◽  
Critical Value ◽  
Stress Criterion ◽  
Tension Tests ◽  
Rubber Sleeve ◽  
Sudden Transition ◽  
Volumetric Stress ◽  
Effect Of Hydrostatic Pressure

A description is given of an apparatus for carrying out tension tests under hydrostatic pressures of 60 ton/in2 or more. The results of an investigation of the effect of hydrostatic pressure on the tensile properties of a number of metals are given. It was found necessary to protect cast materials with a rubber sleeve. The fracture strain increased with hydrostatic pressure, but this increase was not linear but varied with the crystal structure of the metal. In zinc and Mazak a sudden transition from brittle to completely ductile behaviour occurred at a critical pressure; this was probably due to a flat stress/strain curve. It was found in tension tests under pressure that specimens could deform and neck in a characteristic tensile manner, even though all the stresses were compressive. Fracture also could occur when the axial stress was compressive. It was found that the present results on tension, and previous results in torsion on cast iron, conformed either to a criterion that fracture occurred when the largest tensile stress reached a critical value which decreased as the volumetric compressive stress increased, or to a maximum deviatoric stress criterion, the critical value increasing with volumetric stress.

scholarly journals Force parameters of metal deformation during sheet drawing

2020 ◽  
Vol 16 (6) ◽  
pp. 493-503
Author(s):  
Yury A. Morozov
Keyword(s):  
Stress State ◽  
Strain State ◽  
Sheet Material ◽  
Forming Force ◽  
High Quality ◽  
State Process ◽  
The Matrix ◽  
Metal Deformation ◽  
Volumetric Stress ◽  
Steady State Process

The aim of the work. The effect of the curvature of the rounding of torus surfaces during the formation of a cylindrical product (glass) is investigated, taking into account the plastic thinning of the deformable material at the end edges of the matrix and pressing punch. Methods. The existing scheme for determining the power parameters of sheet drawing is analyzed, based on the assumption of the implementation of some abstract stress state in the material; mainly conditional tensile strength. At the same time, the possibility of forming the product without destruction determines the obvious overestimation of the stress level. A mathematical model of the volumetric stress state of the metal is being developed, which makes it possible to assess the deformation and stress state during the formation of a cold-drawn product, i. e. the folding of the sheet blank along the end radius of the rounding of the pressing punch and the steady-state process of drawing the blank into the deformation zone with successive bending/straightening of the material along the edge of the matrix are considered. The level of radial stresses during folding and stretching of sheet material is estimated, taking into account its strain hardening and thinning, which determine the forming force. The obtained results will make it possible to simulate the stress-strain state of the metal during the development of sheet drawing technology: to establish the amount of thinning, to estimate the level of radial stresses in the formation of rounding of torus surfaces along the end edges of the matrix and the pressing punch, as well as to determine the power parameters of the formation, which will prevent the destruction of the pulled part, guaranteeing obtaining high-quality products and more accurately choosing the deforming equipment.

Feasibility and value of two-dimensional volumetric stress echocardiography

2020 ◽  
Author(s):  
Tonino BOMBARDINI ◽  
Angela ZAGATINA ◽  
Quirino CIAMPI ◽  
Lauro CORTIGIANI ◽  
Antonello D'ANDREA ◽  
...  
Keyword(s):  
Stress Echocardiography ◽  
Two Dimensional ◽  
Volumetric Stress

scholarly journals Effect of Stress and Moisture Content on Permeability of Gas-Saturated Raw Coal

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Junhui Wang ◽  
Zhijun Wan ◽  
Yi Wang ◽  
Zhixiang Liu ◽  
Sifei Liu ◽  
...  
Keyword(s):  
Moisture Content ◽  
Coalbed Methane ◽  
Confining Pressure ◽  
Porous Matrix ◽  
In Situ Stress ◽  
Permeability Evolution ◽  
Test Range ◽  
Moisture Contents ◽  
Volumetric Stress

Hydraulic fracturing and premining gas drainage are important to safe mining and coalbed methane extraction. These technical processes cause the redistribution of in-situ stress and the regional variation of moisture contents within the affected zone. Therefore, we investigated the coupled effect of variable stresses (from 9 MPa to 27 MPa) and moisture contents (from 0.22% to 4.00%) on the permeability evolution of gas-saturated raw coal. The results show that (1) the relationship between the mean effective stress and the permeability can be described by a power function according to the permeability evolution model of the porous matrix established in this study. Besides, the influence mechanisms of moisture on fitting coefficients in the function were analyzed. (2) The permeability decreases with the increase of in-situ stress (e.g., confining pressure or volumetric stress) in a negative exponential manner. (3) The curves of permeability variations with moisture content are not always linear, and the permeability is more sensitive to the moisture content than the volumetric stress in the test range. Moreover, the sensitivity of permeability varies in different regions. These results would be beneficial for permeability prediction and surface well parameters design.

scholarly journals Volumetric Stress-Strain Analysis of Optohydrodynamically Suspended Biological Cells

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Sean S. Kohles ◽  
Yu Liang ◽  
Asit K. Saha
Keyword(s):  
Single Cells ◽  
Strain Analysis ◽  
Optical Tweezer ◽  
Three Dimensions ◽  
Shear Stresses ◽  
Strain Response ◽  
Biological Cells ◽  
Two Dimensional ◽  
Stress Strain ◽  
Volumetric Stress

Ongoing investigations are exploring the biomechanical properties of isolated and suspended biological cells in pursuit of understanding single-cell mechanobiology. An optical tweezer with minimal applied laser power has positioned biologic cells at the geometric center of a microfluidic cross-junction, creating a novel optohydrodynamic trap. The resulting fluid flow environment facilitates unique multiaxial loading of single cells with site-specific normal and shear stresses resulting in a physical albeit extensional state. A recent two-dimensional analysis has explored the cytoskeletal strain response due to these fluid-induced stresses [Wilson and Kohles, 2010, “Two-Dimensional Modeling of Nanomechanical Stresses-Strains in Healthy and Diseased Single-Cells During Microfluidic Manipulation,” J Nanotechnol Eng Med, 1(2), p. 021005]. Results described a microfluidic environment having controlled nanometer and piconewton resolution. In this present study, computational fluid dynamics combined with multiphysics modeling has further characterized the applied fluid stress environment and the solid cellular strain response in three dimensions to accompany experimental cell stimulation. A volumetric stress-strain analysis was applied to representative living cell biomechanical data. The presented normal and shear stress surface maps will guide future microfluidic experiments as well as provide a framework for characterizing cytoskeletal structure influencing the stress to strain response.

scholarly journals Generalized calculating diagram of steel, operating under conditions of volumetric stress state

2017 ◽  
pp. 12-18
Author(s):  
A.L. KRISHAN ◽  
◽  
E.A. TROSHKINA ◽  
E.P. CHERNYSHOVA ◽  
M.A. ASTAFEVA ◽  
...  
Keyword(s):  
Stress State ◽  
Volumetric Stress

Validating the Critical Areal Density for a New Ballistic Armor Exhibiting Blunt Trauma Reduction

2013 ◽  
Author(s):  
Advait Bhat ◽  
Balaji Jayakumar ◽  
Jay C. Hanan
Keyword(s):  
Blunt Trauma ◽  
Areal Density ◽  
Light Weight ◽  
Ballistic Limit ◽  
Finite Element Code ◽  
Design Changes ◽  
Back Face ◽  
Composite Armor ◽  
Relative Design ◽  
Volumetric Stress

Today there are several armor technologies for reducing penetration injuries. Some of the best technologies are light weight, but alone the trauma to the wearer remains significant. The areal density of a new Hybrid Composite Armor (HCA) maintaining compliance with level III NIJ 0101.06 standards was evaluated using ballistic testing and FEM. This new HCA has a multilayered composite design tailored for Behind Armor Blunt Trauma (BABT) reduction. Three areal densities of HCA were ballistic tested using 7.62 FMJ Lead Core projectiles and measurements of Back Face Signature (BFS) and V50 velocities were collected. For comparison, baseline monolith inserts of similar areal densities were also tested. A critical areal density was found to qualify for the standard while demonstrating a 29.4% reduction in BFS (and hence BABT) in comparison to its baseline. This armor design showed the greatest known propensity to reduce injury both due to the light weight and improved trauma performance compared to existing commercial designs. Numerical simulations in finite element code were carried out to validate with the experimental results. A method for evaluating change-in-velocity and volumetric stress distribution plots was presented using a mock HCA-P2 model. In the future, a similar FEA scheme can be used for predicting the ballistic limit and estimating improvements possible in BABT reduction for HCA concepts with relative design changes.

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