scholarly journals The Wall Stress of the Capsule Surface in the Straight Pipe

Water ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 242 ◽  
Author(s):  
Xiaoni Yang ◽  
Juanjuan Ma
Keyword(s):  
Shear Stress ◽  
Principal Stress ◽  
Pipe Flow ◽  
Maximum Shear Stress ◽  
Wall Stress ◽  
Radial Component ◽  
Axial Component ◽  
New Energy ◽  
Flow Field Characteristics ◽  
Great Force

Hydraulic capsule transportation is a new energy-saving transport mode. It is of great significance to the study of flow-field characteristics and pipeline-stress analysis. The purpose of this paper was to analyze the stress distribution on capsule surfaces when there is stationary in pipe flow. Results showed that the maximum shear stress on the capsule wall appeared in the rear section. Shear-stress range was between 0 and 38 Pa. Principal stress exerted great force on the capsule. The circumferential component of the principal stress was the largest, followed by the axial component, and the radial component was the smallest, i.e., σc > σa> σr. The larger the discharge of pipe flow, the greater the influence of unit discharge on wall shear stress and capsule principal stress, that is, k1 < k2< k3. Under the conditions of this experiment, the axial component of principal stress should include shear stress on the capsule, and Reynolds stress on the capsule cannot be neglected due to water-flow turbulence.

Pulsatile Flow in Fusiform Models of Abdominal Aortic Aneurysms: Flow Fields, Velocity Patterns and Flow-Induced Wall Stresses

2004 ◽  
Vol 126 (4) ◽  
pp. 438-446 ◽  
Author(s):  
Robert A. Peattie ◽  
Tiffany J. Riehle ◽  
Edward I. Bluth
Keyword(s):  
Shear Stress ◽  
Pulsatile Flow ◽  
Maximum Shear Stress ◽  
Wall Stress ◽  
Abdominal Aortic Aneurysms ◽  
Flow Fields ◽  
Aortic Aneurysms ◽  
Abdominal Aortic ◽  
Risk Of Rupture

As one important step in the investigation of the mechanical factors that lead to rupture of abdominal aortic aneurysms, flow fields and flow-induced wall stress distributions have been investigated in model aneurysms under pulsatile flow conditions simulating the in vivo aorta at rest. Vortex pattern emergence and evolution were evaluated, and conditions for flow stability were delineated. Systolic flow was found to be forward-directed throughout the bulge in all the models, regardless of size. Vortices appeared in the bulge initially during deceleration from systole, then expanded during the retrograde flow phase. The complexity of the vortex field depended strongly on bulge diameter. In every model, the maximum shear stress occurred at peak systole at the distal bulge end, with the greatest shear stress developing in a model corresponding to a 4.3 cm AAA in vivo. Although the smallest models exhibited stable flow throughout the cycle, flow in the larger models became increasingly unstable as bulge size increased, with strong amplification of instability in the distal half of the bulge. These data suggest that larger aneurysms in vivo may be subject to more frequent and intense turbulence than smaller aneurysms. Concomitantly, increased turbulence may contribute significantly to wall stress magnitude and thereby to risk of rupture.

scholarly journals Numerical Investigation of a Hydrosplitting Fracture and Weak Plane Interaction Using Discrete Element Modeling

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 535
Author(s):  
Shuaiqi Liu ◽  
Fengshan Ma ◽  
Haijun Zhao ◽  
Jie Guo ◽  
Xueliang Duan ◽  
...  
Keyword(s):  
Shear Stress ◽  
Principal Stress ◽  
Stress Ratio ◽  
Water Pressure ◽  
Maximum Shear Stress ◽  
Water Inrush ◽  
Discrete Element ◽  
Maximum Principal Stress ◽  
In Situ Stress

Water inrush caused by hydrosplitting is an extremely common disaster in the engineering of underground tunnels. In this study, the propagation of fluid-driven fractures based on an improved discrete element fluid-solid coupling method was modeled. First, the interactions between hydrosplitting fractures (HFs) and preexisting weak planes (WPs) with different angles were simulated considering water pressure in the initial fracture. Second, the influence of the in situ stress ratio and the property of WPs were analyzed, and corresponding critical pressure values of different interactions were calculated. Lastly, the maximum principal stress and maximum shear stress variation inside the pieces were reproduced. The following conclusions can be drawn: (1) Five different types of interaction modes between HFs and natural WPs were obtained, prone to crossing the WPs under inclination of 90°. (2) The initiation pressure value decreased with an increased in situ stress ratio, and the confining stress status had an effect on the internal principal stress. (3) During HFs stretching in WPs with a high elastic modulus, the value of the maximum principal stress was low and rose slowly, and the maximum shear stress value was smaller. Through comprehensive analysis, the diversity of the principal stress curves is fundamentally determined by the interaction mode between HFs and WPs, which are influenced by the variants mentioned in the paper. The analysis provides a better guideline for understanding the failure mechanism of water gushing out of deep buried tunnel construction and cracking seepage of high head tunnels.

Mechanics of Cell Mechanosensing on Patterned Substrate

2016 ◽  
Vol 83 (5) ◽  
Author(s):  
Chenglin Liu ◽  
Shijie He ◽  
Xiaojun Li ◽  
Bo Huo ◽  
Baohua Ji
Keyword(s):  
Shear Stress ◽  
Principal Stress ◽  
Maximum Shear Stress ◽  
Cell Monolayer ◽  
Maximum Principal Stress ◽  
Mechanical Force ◽  
Shear Stresses ◽  
Plane Shear ◽  
Cell Behaviors ◽  
Mechanical Signals

It has been recognized that cells are able to actively sense and respond to the mechanical signals through an orchestration of many subcellular processes, such as cytoskeleton remodeling, nucleus reorientation, and polarization. However, the underlying mechanisms that regulate these behaviors are largely elusive; in particular, the quantitative understanding of these mechanical responses is lacking. In this study, combining experimental measurement and theoretical modeling, we studied the effects of rigidity and pattern geometry of substrate on collective cell behaviors. We showed that the mechanical force took pivotal roles in regulating the alignment and polarization of cells and subcellular structures. The cell, cytoskeleton, and nucleus preferred to align and polarize along the direction of maximum principal stress in cell monolayer, and the driving force is the in-plane maximum shear stress. The higher the maximum shear stress, the more the cells and their subcellular structures preferred to align and polarize along the direction of maximum principal stress. In addition, we proved that in response to the change of in-plane shear stresses, the actin cytoskeleton is more sensitive than the nucleus. This work provides important insights into the mechanisms of cellular and subcellular responses to mechanical signals. And it also suggests that the mechanical force does matter in cell behaviors, and quantitative studies through mechanical modeling are indispensable in biomedical and tissue engineering applications.

ASME Sec VIII Div 3 Fatigue Life Predictions Using Critical Plane Approach

2015 ◽  
Author(s):  
Kumarswamy Karpanan ◽  
William Thomas
Keyword(s):  
Shear Stress ◽  
Fatigue Life ◽  
Principal Stress ◽  
Stress Amplitude ◽  
Maximum Shear Stress ◽  
Fe Model ◽  
Critical Plane ◽  
Principal Stress Direction ◽  
Stress Direction ◽  
Surface Node

ASME VIII Div 3 fatigue evaluation is based on the theory that cracks tend to nucleate along the slip lines oriented in the maximum shear stress planes. This code provides methods to calculate the fatigue stresses when the principal stress direction does not change (proportional loading) and axes change (nonproportional loading). When principal stress direction does not change within a fatigue cycle, shear stress amplitude is calculated only on the three maximum shear stress planes. But when the principal stress directions do change within a loading cycle, the plane carrying the maximum shear stress amplitude (also known as critical plane) cannot be easily identified and all planes at a point needs to be searched for the maximum shear stress amplitude. This paper describes the development of an ANSYS-APDL macro to predict the critical plane at each surface node of an FE model using the FEA stress results. This macro searches through 325 planes (at 10° increments along two angles) at each surface node and for each load step to identify the maximum shear stress and the corresponding normal stress for each surface node. The fatigue life is calculated for each surface node and is plotted as a color contour on the FEA model. This macro can be extended to calculate the fatigue life using other critical plane approaches such as the Findley and Brown-Miller models.

A Shearing Strain Model for Cylindrical Stress States

2019 ◽  
Vol 62 (1) ◽  
pp. 225-230
Author(s):  
Clarence E. Johnson ◽  
Alvin C. Bailey ◽  
Thomas R. Way
Keyword(s):  
Shear Stress ◽  
Principal Stress ◽  
Maximum Shear Stress ◽  
Volumetric Strain ◽  
Triaxial Tests ◽  
Soil Parameters ◽  
Shear Stresses ◽  
Stress States ◽  
Shearing Strain ◽  
Strain Model

Abstract. A shearing strain model for soil was developed that includes soil behavior under compressive normal and shear stresses great enough to attain maximum compaction. The model was developed for a clay and a clay loam from triaxial data with various stress loading paths. This model relates the ratio of maximum shear stress acting on the cylindrical sample (tmax) to major principal stress (s1), to the ratio of maximum natural shearing strain to natural volumetric strain occurring after shear stress is initiated. The model accurately describes the shearing distortion of triaxial soil samples under cylindrical stress loading prior to yielding by plastic flow. This model predicts soil shearing strain for input stress states that realistically represent field conditions. Keywords: Principal stress and strain, Shearing strain, Shear stress, Soil compaction, Soil parameters, Triaxial tests.

Constitutive-Related Instabilities in Pipe Flow of a Viscoelastic Fluid

2001 ◽  
Author(s):  
Manuel A. Alves ◽  
Fernando T. Pinho ◽  
Paulo J. Oliveira
Keyword(s):  
Shear Stress ◽  
Steady State ◽  
Shear Rate ◽  
Pipe Flow ◽  
A Priori ◽  
Maximum Shear Stress ◽  
Steady State Solution ◽  
Plane Shear ◽  
Radial Profiles ◽  
New Finding

Abstract The analytical solution for the steady-state flow in a pipe of viscoelastic fluids obeying the complete Phan-Thien-Tanner constitutive equation with a linear stress coefficient is derived. The results include the radial profiles of all relevant stresses, of the axial velocity and of the viscosity. The pipe flow is found to be unstable when the pressure gradient exceeds a critical value determined by a maximum shear rate at the wall. Expressions are also given for the viscometric viscosity and the first and second normal stress difference coefficients, as a function of the shear rate, in steady plane shear flow. For this case, and in line with similar results for the Johnson-Segalman model, the shear stress was found not to be a monotonically increasing function of the shear rate as strong shear-thinning sets in. A new finding is that the critical condition for the maximum shear stress in the simple-shear case is related to the condition for existence of steady-state solution in the pipe flow case. While this may seem evident “a priori” since the pipe flow is a viscometric flow, it is formally demonstrated.

scholarly journals Design of Tapered Flatted End Tube for Tension and Compression Loading

2019 ◽  
Vol 8 (6) ◽  
pp. 1047-1057
Keyword(s):  
Shear Stress ◽  
Principal Stress ◽  
Circular Tube ◽  
Maximum Shear Stress ◽  
Maximum Principal Stress ◽  
Space Structure ◽  
Bolted Joints ◽  
Space Structures ◽  
Bolted Connection ◽  
Tension And Compression

Hollow circular tube has the most efficient section in space structure. Hollow circular tube joint either welding or bolting but welding aluminum structural alloys lead to unavoidable annealing which can reduce efficiency to the order of only 50%. The efficiency of riveted and bolted joints is usually assumed to be around 75% in both aluminum and steel construction. Welded connections give the maximum strength in steel space structures and used for large spans. Hollow circular tube flatted at the end for single bolted connection and at flatted end increase this thickness for reducing stresses and this thicker plate make a hole for single bolted connection. Study this performance for varies the tapered flattened angle tube. Apply vertically upward and downward incremental load on the tapered flatted end tube at fixed bolted joint in ANSYS. Run this model for maximum shear stress and maximum principal stress. Find out the allowable tensile and compression stress in simple hollow circular tube in SAP2000 as per IS800-2007.. Find out the design load as per maximum shear stress theories and maximum principal stress theories

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.

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