Observations of Shear Localization in Liquid Lubricants Under Pressure

1993 ◽  
Vol 115 (3) ◽  
pp. 507-513 ◽  
Author(s):  
S. Bair ◽  
F. Qureshi ◽  
W. O. Winer
Keyword(s):  
Shear Stress ◽  
Deformation Behavior ◽  
Shear Bands ◽  
Solid Surfaces ◽  
Parallel Plates ◽  
Newtonian Flow ◽  
Contact Conditions ◽  
Fundamental Investigation ◽  
Spatial Periodicity ◽  
Nonlinear Shear

A High Pressure Flow Visualization Cell has been designed and constructed to perform a fundamental investigation of the deformation behavior of liquid lubricants under lubricated concentrated contact conditions. A pressure of 0.3 GPa and a shear stress between parallel plates of about 25 MPa has been demonstrated. Time averaged velocity profiles show no continuous slip either in the bulk or at walls. Localized slip at shear bands inclined to the walls was demonstrated to occur during nonlinear shear response. The number of shear bands increases with shear rate (and shear stress) from as few as one at the onset of non-Newtonian flow until the shear region is essentially filled with bands with a spatial periodicity of 7 μm. Bands are typically inclined 19 deg off the solid surfaces in a direction which reduces the compressive normal stress due to shear on the plane of the band.

scholarly journals The Effect of Wall Shear Stress on Two Phase Fluctuating Flow of Dusty Fluids by Using Light Hill Technique

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1587
Author(s):  
Dolat Khan ◽  
Ata ur Rahman ◽  
Gohar Ali ◽  
Poom Kumam ◽  
Attapol Kaewkhao ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Base Fluid ◽  
Perturbation Technique ◽  
Fluid Velocity ◽  
Dust Particles ◽  
Stress Effect ◽  
Parallel Plates ◽  
Dusty Fluid ◽  
Wall Shear

Due to the importance of wall shear stress effect and dust fluid in daily life fluid problems. This paper aims to discover the influence of wall shear stress on dust fluids of fluctuating flow. The flow is considered between two parallel plates that are non-conducting. Due to the transformation of heat, the fluid flow is generated. We consider every dust particle having spherical uniformly disperse in the base fluid. The perturb solution is obtained by applying the Poincare-Lighthill perturbation technique (PLPT). The fluid velocity and shear stress are discussed for the different parameters like Grashof number, magnetic parameter, radiation parameter, and dusty fluid parameter. Graphical results for fluid and dust particles are plotted through Mathcad-15. The behavior of base fluid and dusty fluid is matching for different embedded parameters.

Steel Sheet Shear Walls with Burring Holes for Low- to Mid-Rise Housings

2019 ◽  
Author(s):  
Yoshimichi Kawai ◽  
Shigeaki Tohnai ◽  
Shinichiro Hashimoto ◽  
Atsushi Sato ◽  
Tetsuro Ono
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Large Deformation ◽  
Deformation Behavior ◽  
Steel Sheet ◽  
Shear Walls ◽  
Shear Load ◽  
Finite Element Analyses ◽  
Plane Shear ◽  
Out Of Plane

<p>Steel sheet shear walls with cold formed edge stiffened burring holes are applied to low- to mid-rise housings in seismically active and typhoon- or hurricane-prone regions. A configuration with burrs on the inside and smooth on the outside enables the construction of omitting the machining of holes for equipments and thinner walls with simplified attachments of finishings. In-plane shear experiments and finite element analyses revealed that the walls allowed shear stress to concentrate in intervals between the burring holes. The walls maintained stable shear load and large deformation behavior, and the deformation areas were limited in the intervals and a large out-of-plane waveform in a sheet was effectively prevented owing to edge stiffened burring ribs. The design methods are developed for evaluating the shear load of the walls at story angle from zero to 1/100, using the idea of decreasing the band width of the inclined tension fields on the intervals with the effects of the thickness.</p>

scholarly journals Pulsating Flow of an Ostwald—De Waele Fluid between Parallel Plates

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 932
Author(s):  
Rodrigo González ◽  
Aldo Tamburrino ◽  
Andrea Vacca ◽  
Michele Iervolino
Keyword(s):  
Shear Stress ◽  
Analytical Solution ◽  
Wall Shear Stress ◽  
Pressure Gradient ◽  
Velocity Distribution ◽  
Momentum Equation ◽  
Parallel Plates ◽  
Analytical Computation ◽  
Pulsatile Pressure ◽  
Pulsatile Pressure Gradient

The flow between two parallel plates driven by a pulsatile pressure gradient was studied analytically with a second-order velocity expansion. The resulting velocity distribution was compared with a numerical solution of the momentum equation to validate the analytical solution, with excellent agreement between the two approaches. From the velocity distribution, the analytical computation of the discharge, wall shear stress, discharge, and dispersion enhancements were also computed. The influence on the solution of the dimensionless governing parameters and of the value of the rheological index was discussed.

Compressive properties of bulk metallic glass with small aspect ratio

2007 ◽  
Vol 22 (2) ◽  
pp. 501-507 ◽  
Author(s):  
F.F. Wu ◽  
Z.F. Zhang ◽  
S.X. Mao
Keyword(s):  
Plastic Deformation ◽  
Aspect Ratio ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Deformation Behavior ◽  
Shear Bands ◽  
Compressive Load ◽  
Small Aspect Ratio ◽  
Compressive Properties ◽  
Deformation Ability

The quasi-static compressive deformation behavior of a Vitreloy 1 bulk metallic glass (BMG) with an aspect ratio of 0.25 was investigated. It is found that the friction and the confinement at the specimen–loading platen interface will cause the dramatic increase in the compressive load, leading to higher compressive strength. In particular, the BMG specimens show great plastic-deformation ability, and plenty of interacted, deflected, wavy, or branched shear bands were observed on the surfaces after plastic deformation. The formation of the strongly interacted, deflected, wavy, or branched shear bands can be attributed to the triaxial stress state in the glassy specimens with a very small aspect ratio.

scholarly journals Hot Deformation Behavior of Cu–Sn–La Polycrystalline Alloy Prepared by Upcasting

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3739
Author(s):  
Siming Hua ◽  
Pingze Zhang ◽  
Zili Liu ◽  
Lin Yang
Keyword(s):  
Dynamic Recrystallization ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Testing Machine ◽  
Shear Bands ◽  
Strain Curve ◽  
Extrusion Process ◽  
Hot Deformation Behavior ◽  
Polycrystalline Alloy ◽  
Promising Application

In this study, the hot deformation of a Cu–0.55Sn–0.08La (wt.%) alloy was studied using a Gleeble-3180 testing machine at deformation temperatures of 400–700 °C and various strain rates. The stress–strain curve showed that the hot deformation behavior of the Cu–0.55Sn–0.08La (wt.%) alloy was significantly affected by work hardening, dynamic recovery, and dynamic recrystallization. The activation energy Q was 261.649 kJ·mol−1 and hot compression constitutive equation was determined as  ε˙=[sinh(0.00651σ)]10.2378·exp(33.6656−261.649RT). The microstructural evolution of the alloy during deformation at 400 °C revealed the presence of both slip and shear bands in the grains. At 700 °C, dynamic recrystallization grains were observed, but recrystallization was incomplete. In summary, these results provide the theoretical basis for the continuous extrusion process of alloys with promising application prospects in the future.

scholarly journals Internal Damper Characteristics of Rotor System with Submerged ER Fluid Journal Bearing

1997 ◽  
Vol 3 (1) ◽  
pp. 61-71 ◽  
Author(s):  
Siyoul Jang ◽  
John A. Tichy
Keyword(s):  
Shear Stress ◽  
Electric Field ◽  
Shear Strain ◽  
Yield Stress ◽  
Electric Fields ◽  
Journal Bearing ◽  
Shear Strain Rate ◽  
Newtonian Flow ◽  
Damping Coefficients ◽  
Er Fluid

Electro-Rheological (ER) fluid behavior is similar to Bingham fluid’ s. Only when the shear stress magnitude of ER fluid exceeds the yield stress, Newtonian flow results. Continuous shear strain rate equation about shear stress which simulates Bingham-like fluid shows viscosity variations. Shear yield stress is controlled by electric fields. Electric fields in circumferential direction around the journal are also changeable because of gap distance. These values make changes of spring and damping coefficients of journal bearings compared to Newtonian flow case. Implicit viscosity variation effects according to shear strain rates of fluid are included in generalized Reynolds' equation for submerged journal bearing. Fluid film pressure and perturbation pressures are solved using switch function of Elord's algorithm for cavitation boundary condition. Spring and damping coefficients are obtained for several parameters that determine the characteristics of ER fluids under a certain electric field. From these values stability region for simple rotor-bearing system is computed. It is found that there are no big differences in load capacities with the selected electric field parameters at low eccentric region and higher electric field can support more load with stability at low eccentric region.

Deformation Behavior of Cu-8wt%Ag Alloy during Equal Channel Angular Pressing

2015 ◽  
Vol 1101 ◽  
pp. 93-98
Author(s):  
Yue Shen ◽  
Chuan Ting Ren ◽  
Guo Quan Zhang ◽  
Ming Xie ◽  
Ming Wen ◽  
...  
Keyword(s):  
Shear Deformation ◽  
Equal Channel Angular Pressing ◽  
Deformation Behavior ◽  
Shear Bands ◽  
Vertical Plane ◽  
Vertical Shear ◽  
Ecap Processing ◽  
Angular Pressing ◽  
Micro Level ◽  
The One

The shear deformation behavior of the course-grained Cu-8wt%Ag alloy processed by one pass of equal channel angular pressing (ECAP) was revealed through the metallurgical microscope and the scanning electron microscope. Through the macro-level and micro-level synthesis analysis, it is confirmed that there are two shear deformation during the ECAP processing: the one along the intersection plane (IP) and the other along the vertical plane to the IP. And it is estimated that theoretical ranges of two shear angles are-32°<θ1<0° and 43°<θ2<58° respectively. Finally, it is also proved that the evolution of the shear bands is affected by the parallel and vertical shear to the IP of the ECAP die, and that, besides the shear along the IP, the shear along the vertical plane to the IP also plays an important role during the plastic deformation.

Determination of Shear Stress at a Solder Paste/Stencil Interface

1993 ◽  
Vol 323 ◽  
Author(s):  
Linda M. Head ◽  
Vincent Rogers ◽  
Chitteranjan Sahay ◽  
James Constable
Keyword(s):  
Shear Stress ◽  
Mechanical Test ◽  
Test Procedure ◽  
Shear Thinning ◽  
Solder Paste ◽  
Parallel Plates ◽  
Release Process ◽  
Stencil Printing ◽  
Plate Separation ◽  
Lift Off

AbstractTo create a model for the release process of solder paste during stencil printing for surface mount applications it is necessary to determine the shear stress developed at the interface between the solder paste and stencil sidewall. An experiment has been developed to determine the value of the shear stress for solder paste samples. For the purpose of this experiment a Micro-mechanical tester has been adapted and programmed to provide both a shear thinning cycle and a pull-off cycle that simulate aperture fill and stencil lift-off. The shear stress developed at the solder/stencil-sidewall interface is estimated from the data obtained during the pull-off portion of the Micro-mechanical test procedure. The micro-mechanical tester is fitted with a set of parallel plates that can be adjusted for plate separation and surface roughness.The experiment consists of two parts: (1) the shear thinning cycle and (2) the horizontal pull-off. After application of the solder paste and adjustment of plate separation, a back and forth movement of the upper plate provides shear thinning of the paste. This step is necessary to simulate the shear thinning that occurs from the application of squeege pressure during aperture fill. The horizontal pull-off then simulates the lift-off step of the stencil printing procedure. During the horizontal pull-off data is. taken which allows calculation of the force developed as the upper plate is pulled away from the lower. Results from this experiment show the values of shear stress that develop during pull-off with a variation of surface treatments and plate separations.This paper will present the experimental set-up, a description of the relationship between this experiment and the actual stencil lift-off process, and shear stress data that has been acquired for a variety of solder pastes and plate separations.

Nonuniform Temperature Distribution in Adiabatic Shear Band Using Measured Shear Stress-Shear Strain Curve in Torsion of Thin-Walled Tube Aluminium Alloy Specimen and Gradient-Dependent Plasticity

2006 ◽  
Vol 519-521 ◽  
pp. 865-870 ◽  
Author(s):  
X.B. Wang
Keyword(s):  
Shear Stress ◽  
Strain Rate ◽  
Shear Strain ◽  
Temperature Rise ◽  
Strain Curve ◽  
Local Temperature ◽  
Dependent Plasticity ◽  
Peak Shear Stress ◽  
Nonlinear Shear ◽  
Shear Strain Curve

Gradient-dependent plasticity where a characteristic length is involved to consider the microstructural effect (interactions and interplaying among microstructures due to the heterogeneous texture) and the measured nonlinear shear stress-shear strain curves for different loading strain rates are used to calculate the distribution of local temperature rise in adiabatic shear band (ASB) for aluminum-lithium alloy specimen of thin-walled tube in dynamic torsion test. ASB is assumed to initiate just at peak shear stress in the specimen. The temperature rise in ASB is decomposed into the uniform temperature rise in strain-hardening stage and the nonuniform temperature rise in strain-softening stage. The former depends on the measured nonlinear shear stress-shear strain curve prior to the peak, the density, the work to heat conversion factor and the heat capacity. The latter is related to the softening branch of the measured nonlinear shear stress-shear strain curve, the internal length parameter and the physical parameters. For binary Al-Li alloy, the predicted maximum temperatures in ASB are 413K at strain rate of 2000s-1 and 433K at strain rate of 2600s-1. These peak temperatures are lower than the recrystallization and phase transformation temperatures. Higher loading strain rate results in higher pre-peak and post-peak temperature rises, steeper profile of local temperature and higher peak local temperature in ASB. These predictions qualitatively agree with the previously analytical solution for ductile metal exhibiting linear strain-softening behavior beyond the peak shear stress based on gradient-dependent plasticity.

Amorphous Phase Formation in NiTi During Cold Rolling

1990 ◽  
Vol 186 ◽  
Author(s):  
J. Koike ◽  
D. M. Parkin ◽  
M. Nastasi
Keyword(s):  
Shear Stress ◽  
Room Temperature ◽  
Shear Bands ◽  
Mechanical Instability ◽  
Microstructural Morphology ◽  
Cold Rolled ◽  
Pure Metals ◽  
State Amorphization ◽  
Amorphous Phase Formation ◽  
Crystalline Matrix

AbstractThe intermetallic compound NiTi was cold rolled at room temperature. Amorphous bands were formed within the finely twined crystalline matrix after thickness reduction of 60%. Striking similarities were observed in microstructural morphology between amorphous bands and shear bands that are generally observed in heavily cold-rolled pure metals. We suggest from the present observations together with the reported results in other solid-state amorphization experiments that the amorphous bands are produced in the shear bands, and that amorphization is caused by mechanical instability against the shear stress.

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