scholarly journals Studying the performance of fully encapsulated rock bolts with modified structural elements

2021 ◽  
Author(s):  
Jianhang Chen ◽  
Hongbao Zhao ◽  
Fulian He ◽  
Junwen Zhang ◽  
Kangming Tao
Keyword(s):  
Shear Stress ◽  
Load Transfer ◽  
Maximum Shear Stress ◽  
Coupling Model ◽  
Numerical Approach ◽  
Rock Bolt ◽  
Structural Elements ◽  
Rock Bolts ◽  
Two Stage ◽  
Bolt Diameter

AbstractNumerical simulation is a useful tool in investigating the loading performance of rock bolts. The cable structural elements (cableSELs) in FLAC3D are commonly adopted to simulate rock bolts to solve geotechnical issues. In this study, the bonding performance of the interface between the rock bolt and the grout material was simulated with a two-stage shearing coupling model. Furthermore, the FISH language was used to incorporate this two-stage shear coupling model into FLAC3D to modify the current cableSELs. Comparison was performed between numerical and experimental results to confirm that the numerical approach can properly simulate the loading performance of rock bolts. Based on the modified cableSELs, the influence of the bolt diameter on the performance of rock bolts and the shear stress propagation along the interface between the bolt and the grout were studied. The simulation results indicated that the load transfer capacity of rock bolts rose with the rock bolt diameter apparently. With the bolt diameter increasing, the performance of the rock bolting system was likely to change from the ductile behaviour to the brittle behaviour. Moreover, after the rock bolt was loaded, the position where the maximum shear stress occurred was variable. Specifically, with the continuous loading, it shifted from the rock bolt loaded end to the other end.

Flow and Thermal Fields in a Pendant Droplet Moving on Lyophobic Surface

2010 ◽  
Author(s):  
Basant Singh Sikarwar ◽  
K. Muralidhar ◽  
Sameer Khandekar
Keyword(s):  
Heat Transfer ◽  
Contact Angle ◽  
Reynolds Number ◽  
Shear Stress ◽  
Heat Transfer Coefficient ◽  
Wall Shear Stress ◽  
Transfer Coefficient ◽  
Maximum Shear Stress ◽  
Computational Domain ◽  
Wall Shear

Clusters of liquid drops growing and moving on physically or chemically textured lyophobic surfaces are encountered in drop-wise mode of vapor condensation. As opposed to film-wise condensation, drops permit a large heat transfer coefficient and are hence attractive. However, the temporal sustainability of drop formation on a surface is a challenging task, primarily because the sliding drops eventually leach away the lyophobicity promoter layer. Assuming that there is no chemical reaction between the promoter and the condensing liquid, the wall shear stress (viscous resistance) is the prime parameter for controlling physical leaching. The dynamic shape of individual droplets, as they form and roll/slide on such surfaces, determines the effective shear interaction at the wall. Given a shear stress distribution of an individual droplet, the net effect of droplet ensemble can be determined using the time averaged population density during condensation. In this paper, we solve the Navier-Stokes and the energy equation in three-dimensions on an unstructured tetrahedral grid representing the computational domain corresponding to an isolated pendant droplet sliding on a lyophobic substrate. We correlate the droplet Reynolds number (Re = 10–500, based on droplet hydraulic diameter), contact angle and shape of droplet with wall shear stress and heat transfer coefficient. The simulations presented here are for Prandtl Number (Pr) = 5.8. We see that, both Poiseuille number (Po) and Nusselt number (Nu), increase with increasing the droplet Reynolds number. The maximum shear stress as well as heat transfer occurs at the droplet corners. For a given droplet volume, increasing contact angle decreases the transport coefficients.

A critical look at the Wallace-Bott hypothesis in fault-slip analysis

2013 ◽  
Vol 184 (4-5) ◽  
pp. 299-306 ◽  
Author(s):  
Richard J. Lisle
Keyword(s):  
Shear Stress ◽  
Maximum Shear Stress ◽  
Fault Slip ◽  
Shear Stresses ◽  
Homogeneous State ◽  
Slip Direction ◽  
Fault Surface ◽  
State Of Stress ◽  
Simultaneous Movement

AbstractThe assumption is widely made that slip on faults occurs in the direction of maximum resolved shear stress, an assumption known as the Wallace-Bott hypothesis. This assumption is used to theoretically predict slip directions from known in situ stresses, and also as the basis of palaeostress inversion from fault-slip data. This paper examines different situations in relation to the appropriateness of this assumption. Firstly, it is shown that the magnitude of the shear stress resolved within a plane is a function with a poorly defined maximum direction, so that shear stress values greater than 90% of the maximum occur within a wide angular range (± 26°) degrees. The situation of simultaneous movement on pairs of faults requires slip on each fault to be parallel to their mutual line of intersection. However, the resolved shear stresses arising from a homogeneous state of stress do not accord with such a slip arrangement except in the case of pairs of perpendicular faults. Where fault surfaces are non-planar, the directions of resolved shear stress in general give, according to the Wallace-Bott hypothesis, a set of slip directions of rigid fault blocks, which is generally kinematically incompatible. Finally, a simple model of a corrugated fault suggests that any anisotropy of the shear strength of the fault such as that arising from fault surface topography, can lead to a significant angular difference between the directions of maximum shear stress and the slip direction.These findings have relevance to the design of procedures used to estimate palaeostresses and the amount of data required for this type of analysis.

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.

scholarly journals Aging Effect on Structure, Hardness, Roughness Behavior and Bacterial Adhesion on Silver- Palladium Dental Alloy

2020 ◽  
pp. 1-3
Author(s):  
Abu Bakr El-Bediwi ◽  
◽  
Doaa Al- Ragae ◽  
Thoraya El-Helaly ◽  
◽  
...  
Keyword(s):  
Shear Stress ◽  
Bacterial Adhesion ◽  
Maximum Shear Stress ◽  
Aging Effect ◽  
Base Line ◽  
Palladium Alloy ◽  
Dental Alloy ◽  
Roughness Parameters ◽  
Candida Spp ◽  
Silver Palladium

Aging in normal saliva for different interval times make a change in internal structure (Formed phases and started base line) of Sliver- Palladium (Ag-Pd) dental alloy. Also aging in saliva for one, two and three weeks decreased Vickers hardness value, calculated maximum shear stress (τm) and roughness parameters for Sliver- Palladium alloy. Microbiological studies show the Candida spp. stuck on Sliver- Palladium alloy surface and their growth dependent on aging times.

scholarly journals Numerical Study of Fluid Dynamics in Suspension Culture of iPS Cells

2019 ◽  
Vol 17 (1) ◽  
pp. 73 ◽  
Author(s):  
Masaki Yano ◽  
Takuya Yamamoto ◽  
Yasunori Okano ◽  
Toshiyuki Kanamori ◽  
Mashiro Kino–oka
Keyword(s):  
Shear Stress ◽  
Suspension Culture ◽  
Numerical Study ◽  
Maximum Shear Stress ◽  
Ips Cells ◽  
Stirred Tanks ◽  
Average Shear Stress ◽  
Average Shear ◽  
Orbital Shaking ◽  
Induced Pluripotent

In a suspension culture of iPS cells, the shear stress generated during mixing is expected to promote differentiation of induced pluripotent stem (iPS) cells. The stress on the cells can be controlled by rotational rate and shape of impeller. However, it is difficult to optimize these operative parameters by experiments. Therefore, we have developed a numerical model to obtain the average and the maximum shear stress in two kinds of stirred tanks and an orbital shaking cylindrical container. The present results showed that the shear stress strongly depended on the type of mixing and lesser extent on the shape of the impeller. The average shear stress is larger in the shaking mode than that in the stirring mode. In contrast, the maximum shear stress is much smaller in the shaking than the stirring. These results suggest that stirring and shaking should be selectively used depending on the application

scholarly journals The Stress Induced Martensite-Austenite Interface in Fe-15Ni-15Cr Single Crystals

1973 ◽  
Vol 31 ◽  
pp. 110-111
Author(s):  
G. A. Stone ◽  
G. Thomas
Keyword(s):  
Shear Stress ◽  
Slip System ◽  
Single Crystal ◽  
Single Crystals ◽  
Habit Plane ◽  
Maximum Shear Stress ◽  
Crystal Axis ◽  
Surface Study

A single crystal stressed in the [3]𝛄 direction at 185°K was transformed to 5% 𝛂 martensite and 2% Ɛ martensite by volume. The austenite slip system of maximum shear stress is the (11)𝛄 [01)𝛄. Fig. 1 shows a two surface study using the electron and optical microscopes. The a martensite is confined between £martensite plates with the (0001)Ɛ ∥ (11)𝛄. The size of the acicular martensite crystals is controlled by the spacing of the £ martensite plates. These £ martensite plates are seen in Fig. 1A as dark vertical bands. The axes of the acicular crystals lie in the (11)𝛄 plane. The £ martensite habit plane is defined as the plane perpendicular to the (11)𝛄 containing the vector defining the crystal axis.

scholarly journals Shear Stress Distribution in the Opening Chords of Hybrid R/C T-Beams with Opening

2018 ◽  
Vol 147 ◽  
pp. 01005
Author(s):  
Jonie Tanijaya
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Shear Force ◽  
Maximum Shear Stress ◽  
Shear Stress Distribution ◽  
Shear Stresses ◽  
Web Openings ◽  
The Right ◽  
Lower Corner ◽  
T Beam

This study is carried out to evaluate the potential of three hybrid T-beams with web openings theoretical shear stresses distribution. The shear stresses at the opening edges were plotted at the working stage, yielding stage and collapse stage for these three tested beams. The available experimental results from the previous research was compared to the finite element results as well as the developed analytical. The shear stress distribution at the middle of the top and bottom chords of the opening in pure bending region are zero. At the upper and lower corners of the opening occurs the maximum shear stresses. The maximum shear stress occurs at the right lower corner chord at the high moment edge and at the left upper corner chord at the low moment edge in beams with openings at high shear and high flexural – shear region. Furthermore, an extensive parametric study is performed on these beams to find the distributing ratio of the shear force between the opening chords. The shear force at an opening in hybrid R/C T-beam is carried by the top and bottom chords of the opening according to the area – moment of inertia root ratio with the correction factor 0.70.

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