Inhomogeneity problem with a sliding interface under remote shearing stress

2012 ◽  
Vol 55 (11) ◽  
pp. 2122-2127
Author(s):  
YingTao Zhao ◽  
Yang Gao ◽  
MinZhong Wang
Keyword(s):  
Shearing Stress ◽  
Sliding Interface ◽  
Inhomogeneity Problem

scholarly journals Analysis for Stroke Etiology in Duplicated/Accessory MCA-Related Cerebral Infarction: Two Case Report and Brief Literature Review

Diagnostics ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 205
Author(s):  
Kou Tsuyama ◽  
Nobukazu Miyamoto ◽  
Atsuhiko Shindo ◽  
Kenichiro Hira ◽  
Yuji Ueno ◽  
...  
Keyword(s):  
Cerebral Infarction ◽  
Clinical Course ◽  
The Other ◽  
Shearing Stress ◽  
Common Site ◽  
Arterial Diameter ◽  
Stroke Etiology ◽  
Proximal Site ◽  
The Media ◽  
Intracranial Arteries

Duplication and accessory of the middle cerebral artery (MCA) constitute a rare congenital variation. MCA anomalies are found at a lesser frequency than the vascular anomalies of the other major intracranial arteries. Duplicated/accessory MCA was usually noted incidentally with subarachnoid hemorrhage, due to resulted aneurysmal formation. However, duplicated/accessory MCA-related cerebral infarction is rarer. We report two cases of cerebral infarction due to dissection at the entry of the duplicate/accessory MCA. Both cases were similar in dissected site and clinical course, without headache or injury. In 20 previously reported cases and our two cases of duplicated/accessory MCA-related infarction, mean age (55.8 ± 21.2 years) was slightly younger for cerebral infarction, and stroke etiology was mainly embolism. The main etiologies of stroke were embolism and dissection. Considering embolism etiology, proximal site of arterial diameter changing lesion was a common site for embolism, as duplicated/accessory MCA was usually smaller than normal M1 segment. In cerebral dissection cases, the dissected site was similar to our cases. Numerous mechanisms of dissection were considered, but they mainly included dysfunction of the media and endothelium or shearing stress at the entry of duplication. As the detailed mechanisms of cerebral dissection remain unknown, clinicians should include a differential diagnosis for MCA dissection.

Enhanced Tribological Performance of CVD Diamond Films Enabled by Using Graphene Layers as Solid Lubricant

2016 ◽  
Vol 1136 ◽  
pp. 573-578 ◽  
Author(s):  
Su Lin Chen ◽  
Bin Shen ◽  
Fang Hong Sun
Keyword(s):  
Tungsten Carbide ◽  
Solid Lubricant ◽  
Diamond Films ◽  
Cvd Diamond ◽  
Tribological Performance ◽  
Chemical Vapor Deposition Method ◽  
Dry Sliding ◽  
Graphene Layers ◽  
Sliding Interface ◽  
Graphene Flakes

The present study reports the influence of graphene layers on the tribological performance of CVD diamond films when they are used as the solid lubricants. Friction tests are conducted on a ball-on-plate friction tester, where the stainless steel is used as the counterpart material. The CVD diamond film sample is a typical microcrystalline diamond (MCD) coating which is deposited on a flat tungsten carbide substrate using the hot filament chemical vapor deposition method (HFCVD). Besides the MCD sample, a polished MCD film (pMCD) and a polished tungsten carbide (pWC) are also adopted in frictional tests, aiming at illustrating the influence of the surface morphology, as well as the physical property, of the sample on the lubricative effect of graphene layers. The experimental results show that graphene layers can effectively reduce the coefficient of friction (COF), regardless of the samples. The MCD sample presents the lowest stable COF, which is 0.13, in dry sliding period when the graphene flakes are sparyed on the sliding interface; while the pMCD and pWC samples exhibit slightly higher COFs, which are 0.16 and 0.18, respectively. Comparatively, the COFs of these three samples obtained in dry sliding process without graphene are 0.20, 0.25 and 0.64. In additon, the MCD sample exhibits a much longer stable dry slidng process which is more than 5000 cycles. Comparatively, the other two tribo-pairs only exhibit a stable low-COF dry sliding period for around 2000 cycles. The reduction of COF could be attributed to the graphene flakes adhered on the sliding interface. It forms a layer of solid lubricative film with extremely low shear strength and significantly decreases the interactions between two contacted surfaces. The rugged surface of the MCD film provides sufficient clogging locations for graphene flakes, which allows the generated lubricative film enduring a long sliding duration. It can be arrived from this study that the tribological properties of the MCD film could be enhanced by simply adoping graphene layers as a solid lubricant. Furthermore, an improved performance of a variety of MCD coated cutting tools or mechanical components could be expected when they are utilized with graphene layers.

Bidimensional Fluid-Film Flows of Stokesian Fluids

1982 ◽  
Vol 104 (2) ◽  
pp. 227-233
Author(s):  
Patrick Bourgin ◽  
Bernard Gay
Keyword(s):  
Laminar Flow ◽  
Differential Equations ◽  
Boundary Conditions ◽  
Numerical Method ◽  
Differential System ◽  
Analytic Method ◽  
Shearing Stress ◽  
Flow Equations ◽  
Approximate Analytic Method ◽  
Film Flows

The bidimensional flow equations of a Stokesian fluid are solved for the case of steady, incompressible, and laminar flow between two arbitrary moving surfaces separated by a small gap. The stress T22 and the shearing stress at one of the walls are coupled through nonlinear integro-differential equations, depending on the viscous function only. The form of this differential system is specified for the equations derived from the theory of phenomenological macrorheology, as developed by Reiner and Rivlin. The solution is proved to be unique under certain conditions and for adequate boundary conditions. An example is worked out in the particular case of one single non-Newtonian parameter. The problem is solved in two different ways, using an approximate analytic method and a numerical method. The conception of the latter allows to generalize it by introducing only slight modifications into the program.

Combined-Stress Tests on 24S-T Aluminum-Alloy Tubes

1947 ◽  
Vol 14 (2) ◽  
pp. A147-A153
Author(s):  
W. R. Osgood
Keyword(s):  
Aluminum Alloy ◽  
Hoop Stress ◽  
Axial Stress ◽  
Axial Strain ◽  
Maximum Deviation ◽  
Shearing Stress ◽  
Stress Tests ◽  
Combined Stress ◽  
Stress Strain ◽  
Shearing Strain

Abstract Combined-stress tests were made on five 24S-T aluminum-alloy tubes, 1 3/4 in. ID × 0.05 in. thick. The ratios of circumferential (hoop) stress to axial stress were 0, 1/2, 1, 2, and ∞. The tubes were tested to failure and sufficient measurements of circumferential strain and axial strain were taken to plot stress-strain curves almost up to rupture. The results are presented in the form of two sets of stress-strain curves for each ratio of stresses, namely, maximum shearing stress plotted against maximum shearing strain, and octahedral shearing stress plotted against octahedral shearing strain. In each plot the maximum deviation of the curves is about ± 5 per cent. A method of evaluating small octahedral shearing strains from the data is given which does not assume Poisson’s ratio to be 1/2.

Graphical-Numerical Solution of Problems of Saint-Venant Torsion and Bending

1953 ◽  
Vol 20 (3) ◽  
pp. 321-326
Author(s):  
B. A. Boley
Keyword(s):  
Cross Section ◽  
Stress Function ◽  
Arbitrary Cross Section ◽  
Successive Approximations ◽  
Shear Stresses ◽  
Shearing Stress ◽  
First Approximation ◽  
Difference Form ◽  
Bending Of Beams

Abstract A simple successive-approximations procedure for the solution of the problems of Saint-Venant torsion and bending of beams of arbitrary cross section is presented. The shear stresses in a cross section of the beam are first calculated from the formulas valid for thin-walled sections, on the basis of an assumed set of lines of shearing stress. From these a first approximation to the stress function of either the torsion or the bending problem is found. The second approximation to the stress function is then obtained from the governing equation of the problem, expressed in finite-difference form; this in turn allows the determination of an improved set of lines of shearing stress, and hence of the shearing stress itself. The procedure can be repeated until the results of two successive steps are sufficiently close. Applications are presented for a beam cross section for which the exact solutions are known, and it is shown that no further difficulties arise in applications to more complicated shapes.

scholarly journals Clinical, behavioral and biochemical alterations due to shearing stress in Ossimi sheep

2018 ◽  
Vol 80 (8) ◽  
pp. 1281-1286 ◽  
Author(s):  
Abdelghany HEFNAWY ◽  
Mahmoud Atef Youssef HELAL ◽  
Ahmed SABEK ◽  
Saad SHOUSHA
Keyword(s):  
Shearing Stress ◽  
Biochemical Alterations

Preparation and Properties of Nano-Crystalline Cellulose Electro-Rheological Fluid

2015 ◽  
Vol 815 ◽  
pp. 217-221
Author(s):  
Ling Li Xu ◽  
Xing Ling Shi ◽  
Qing Liang Wang
Keyword(s):  
Room Temperature ◽  
Silicone Oil ◽  
Strong Acid ◽  
Crystalline Cellulose ◽  
Methyl Silicone ◽  
Shearing Stress ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nano Crystalline ◽  
Transmission Electron

nanocrystalline cellulose (NCC) was prepared from micro-crystalline cellulose (MCC) by strong acid hydrolysis. The characteristics of such particle were studied by transmission electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. Electro-rheological fluids (ERF) were prepared by dispersing NCC and MCC in methyl-silicone oil, and their ER effects were measured. Experimental results indicated that NCC ERF exhibited a remarkable ER effect. The highest static shearing stress of NCC ERF (3.5 g/ml) was 5.1 kPa at the room temperature under a 4 .2 kV/mm electric field, increased about 5.5 times compared to MCC ERF, and sedimentation of NCC ERF was not observed even after 60 days.

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