Screw Dislocations in a Three-Phase Composite Cylinder Model With Interface Stress

2008 ◽  
Vol 75 (4) ◽  
Author(s):  
Q. H. Fang ◽  
Y. W. Liu ◽  
P. H. Wen
Keyword(s):  
Boundary Condition ◽  
Classical Case ◽  
Interface Stress ◽  
Composite Cylinder ◽  
Screw Dislocations ◽  
Three Phase ◽  
Cylinder Model ◽  
The Matrix ◽  
Stress Boundary Condition ◽  
Stress Boundary

A three-phase composite cylinder model is utilized to study the interaction between screw dislocations and nanoscale inclusions. The stress boundary condition at the interface between nanoscale inclusion and the matrix is modified by incorporating surface/interface stress. The explicit solution to this problem is derived by means of the complex variable method. The explicit expressions of image forces exerted on screw dislocations are obtained. The mobility and the equilibrium positions of the dislocation near one of the inclusions are discussed. The results show that, compared to the classical solution (without interface stress), more equilibrium positions of the screw dislocation may be available when the dislocation is close to the nanoscale inclusion due to consider interface stress. Also, the mobility of the dislocation in the matrix will become more complex than the classical case.

An Edge Dislocation in a Three-Phase Composite Cylinder Model With a Sliding Interface

2002 ◽  
Vol 69 (4) ◽  
pp. 527-538 ◽  
Author(s):  
X. Wang ◽  
Y.-p. Shen
Keyword(s):  
Edge Dislocation ◽  
Arbitrary Point ◽  
Circular Inclusion ◽  
Composite Cylinder ◽  
Phase Form ◽  
Sliding Interface ◽  
Three Phase ◽  
Cylinder Model ◽  
The Matrix ◽  
Perfect Interface

An exact elastic solution is derived in a decoupled manner for the interaction problem between an edge dislocation and a three-phase circular inclusion with circumferentially homogeneous sliding interface. In the three-phase composite cylinder model, the inner inclusion and the intermediate matrix phase form a circumferentially homogeneous sliding interface, while the matrix and the outer composite phase form a perfect interface. An edge dislocation acts at an arbitrary point in the intermediate matrix. This three-phase cylinder model can simultaneously take into account the damage taking place in the circumferential direction at the inclusion-matrix interface and the interaction effect between the inclusions. As an application, we then investigate a crack interacting with the slipping interface.

An Edge Dislocation in a Three-Phase Composite Cylinder Model

1991 ◽  
Vol 58 (1) ◽  
pp. 75-86 ◽  
Author(s):  
H. A. Luo ◽  
Y. Chen
Keyword(s):  
Edge Dislocation ◽  
Stable Equilibrium ◽  
Phase Model ◽  
Composite Cylinder ◽  
Two Phase ◽  
Trapping Mechanism ◽  
Three Phase ◽  
Cylinder Model ◽  
Stable Equilibrium Position ◽  
The Stability

An exact solution is given for the stress field due to an edge dislocation embedded in a three-phase composite cylinder. The force on the dislocation is then derived, from which a set of simple approximate formulae is also suggested. It is shown that, in comparison with the two-phase model adopted by Dundurs and Mura (1964), the three-phase model allows the dislocation to have a stable equilibrium position under much less stringent combinations of the material constants. As a result, the so-called trapping mechanism of dislocations is more likely to take place in the three-phase model. Also, the analysis and calculation show that in the three-phase model the orientation of Burgers vector has only limited influence on the stability of dislocation. This behavior is pronouncedly different from that predicted by the two-phase model.

Analytic stress solution for a circular tunnel in half plane with a concentrated force

2019 ◽  
Vol 24 (12) ◽  
pp. 3862-3879
Author(s):  
Hui Cai ◽  
Ai-zhong Lu ◽  
Yao-cai Ma
Keyword(s):  
Boundary Condition ◽  
Stress Distribution ◽  
Half Plane ◽  
Analytic Functions ◽  
Surrounding Rock ◽  
Circular Tunnel ◽  
Concentrated Force ◽  
Stress Solution ◽  
Stress Boundary Condition ◽  
Stress Boundary

An analytic stress solution is presented for a circular tunnel problem in a half plane with a concentrated force acting on any position in the field under gravity. The solution uses the complex variable method and the power series method. The influence of the unbalanced force system on the tunnel boundary is considered. The relationship between two analytic functions is established by using surface stress boundary condition. The analytic functions can be determined from the tunnel stress boundary condition. Based on the principle of superposition, the stresses of the surrounding rock can be calculated by superimposing three partial solutions which are obtained separately. The examples give contour plots of the principal stresses in the surrounding rock, focus on the stress distribution on the ground surface and the tunnel boundary and analyze the effect on the stress distribution of some main parameters.

Micro-Stress-Field of Lamellar Inclusion in Eutectic Composite Ceramic

2012 ◽  
Vol 204-208 ◽  
pp. 4433-4436 ◽  
Author(s):  
Xie Quan Liu ◽  
Xin Hua Ni ◽  
Jing Zhang ◽  
Xiang Feng Meng
Keyword(s):  
Stress Field ◽  
Composite Ceramic ◽  
Apparent Size ◽  
Phase Cell ◽  
Ceramic Analysis ◽  
Eutectic Composite ◽  
Three Phase ◽  
Stress Boundary Condition ◽  
Stress Boundary ◽  
Remote Stress

According to the interaction between lamellar inclusion and interphase, forth-phase model is suggested to determine the micro-stress-field distribution of three-phase cell in eutectic composite ceramic. On the basis of the volumetric average strain, the effective compliance tensor increment of eutectic composite ceramic is obtained. The remote stress boundary condition of the eutectic composite ceramic is accounted for getting the micro-stress-field of lamellar inclusion in eutectic composite ceramic. Analysis shows that the micro-stress-field of the lamellar inclusion in eutectic composite ceramic is associated with the stiffness and the volume fractions of each component in eutectic composite ceramic, the shape of interphase and lamellar inclusion. The-micro-stress field has apparent size effect: three direction stresses increase with the thickness of lamellar inclusion.

Size Dependent Micro-Stress-Field of Fibers in Eutectic Ceramic Rod

2010 ◽  
Vol 168-170 ◽  
pp. 226-229
Author(s):  
Hai Xing Lu ◽  
Xie Quan Liu ◽  
Xin Hua Ni ◽  
Tao Sun ◽  
Bao Feng Li
Keyword(s):  
Stress Field ◽  
Local Stress ◽  
Apparent Size ◽  
Average Strain ◽  
Size Dependent ◽  
Three Phase ◽  
Stress Boundary Condition ◽  
Stress Boundary ◽  
Remote Stress ◽  
Local Stress Field

Considering the interaction between fiber-inclusion and strong constraining interphase, forth-phase model is suggested to determine the local stress field distribution of three-phase element in eutectic ceramic rod. On the basis of the volumetric average strain, the effective compliance tensor increment of eutectic ceramic rod is obtained. The remote stress boundary condition of the eutectic ceramic rod is accounted for getting the micro stress field of fibers in eutectic ceramic rod. The results show the micro stress field of the fiber-inclusion in eutectic ceramic rod is associated with the stiffness and the volume fractions of each component in eutectic ceramic rod, the shape of interphase and fiber. The micro stress field has apparent size effect: three direction stresses increase with the diameter of fiber- inclusion.

scholarly journals Fluid Driven by Tangential Velocity and Shear Stress: Mathematical Analysis, Numerical Experiment, and Implication to Surface Flow

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
H. S. Tang ◽  
L. Z. Zhang ◽  
J. P.-Y. Maa ◽  
H. Li ◽  
C. B. Jiang ◽  
...  
Keyword(s):  
Boundary Condition ◽  
Shear Stress ◽  
Boundary Conditions ◽  
Steady Flow ◽  
Tangential Velocity ◽  
Surface Flow ◽  
Parallel Plates ◽  
Moving Plate ◽  
Stress Boundary Condition ◽  
Stress Boundary

This paper investigates behaviors of flows driven by tangential velocity and shear stress on their boundaries such as solid walls and water surfaces. In a steady flow between two parallel plates with one of them in motion, analytic solutions are the same when a velocity and a shear stress boundary condition are applied on the moving plate. For an unsteady, impulsively started flow, however, analysis shows that solutions for velocity profiles as well as energy transferring and dissipation are different under the two boundary conditions. In an air-water flow, if either a velocity or a stress condition is imposed at the air-water interface, the problem becomes ill-posed because it has multiple solutions. Only when both of the conditions are specified, it will have a unique solution. Numerical simulations for cavity flows are made to confirm the theoretical results; a tangential velocity and a shear stress boundary condition introduce distinct flows if one considers an unsteady flow, whereas the two conditions lead to a same solution if one simulates a steady flow. The results in this paper imply that discretion is needed on selection of boundary conditions to approximate forcing on fluid boundaries such as wind effects on surfaces of coastal ocean waters.

Bed Shear Stress Boundary Condition for Storage Tank Sedimentation

2003 ◽  
Vol 129 (7) ◽  
pp. 651-658 ◽  
Author(s):  
Åsa Adamsson ◽  
Virginia Stovin ◽  
Lars Bergdahl
Keyword(s):  
Boundary Condition ◽  
Shear Stress ◽  
Storage Tank ◽  
Bed Shear Stress ◽  
Stress Boundary Condition ◽  
Stress Boundary

Fluid Slip of Flow Past a Hydrophobic Wall Sphere

2004 ◽  
Author(s):  
Takao Fujita ◽  
Keizo Watanabe
Keyword(s):  
Boundary Condition ◽  
Drag Reduction ◽  
Flow Visualization ◽  
Flow Characteristics ◽  
Flow Patterns ◽  
Liquid Interface ◽  
Solid Boundary ◽  
Stress Boundary Condition ◽  
Sphere Drag ◽  
Stress Boundary

The possibility of fluid slip has received considerable attention in recent years. Laminar drag reduction is achieved by using a hydrophobic wall with fluid slip. Fluid slip is closely related to the gas-liquid interface formed at a solid surface with many fine grooves. The friction generated by the solid boundary is modified considerably because the gas-liquid interface provides a zero-shear stress boundary condition. The purpose of this study is to experimentally clarify the flow characteristics and drag reduction of a hydrophobic wall sphere by visualizing flow and by measuring the drag. In addition, the flow patterns were numerically analyzed by applying a wet boundary condition for fluid slip. The flow visualization results showed that the Vortex Loop was not exist at Re < 400 in the hydrophobic wall sphere and the separation point moved downstream compared with that of a conventionally smooth sphere. Drag reduction occurred in the flow and the maximum drag reduction ratio was 14.6% at Re=93.2. In this simulation, the flow patterns for the numerical simulation results agreed with those of the flow visualization results.

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