scholarly journals Modeling and investigating of the influence of surface roughness on the strength of electrically conductive fiber

2021 ◽  
pp. 51-59
Author(s):  
Taras Nahirnyj ◽  
Kostiantyn Tchervinka
Keyword(s):  
Surface Roughness ◽  
Fiber Strength ◽  
Double Electric Layer ◽  
Real Surface ◽  
Electronic Subsystem ◽  
Solid Cylinder ◽  
Electrically Conductive ◽  
Near Surface ◽  
Surface Inhomogeneity ◽  
Distribution Features

In the framework of the model of locally inhomogeneous electrically conductive nonferromagnetic solid, the near-surface inhomogeneity in a solid cylinder is investigated. It is shown that such inhomogeneity is characterized by three characteristic sizes associated with the structural inhomogeneity of the material, the roughness of the real surface and the electronic subsystem. The charge distribution features a double electric layer. The size effect of fiber strength and its dependence on geometric inhomogeneity parameters of the surface are studied.

scholarly journals Shear cutting induced residual stresses in involute gears and resulting tooth root bending strength of a fineblanked gear

2021 ◽  
Author(s):  
Daniel Müller ◽  
Jens Stahl ◽  
Anian Nürnberger ◽  
Roland Golle ◽  
Thomas Tobie ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Residual Stresses ◽  
Carrying Capacity ◽  
Bending Strength ◽  
Tooth Root ◽  
Load Carrying Capacity ◽  
Near Surface ◽  
Load Carrying ◽  
Involute Gears ◽  
Cut Surface

AbstractThe manufacturing of case-hardened gears usually consists of several complex and expensive steps to ensure high load carrying capacity. The load carrying capacity for the main fatigue failure modes pitting and tooth root breakage can be increased significantly by increasing the near surface compressive residual stresses. In earlier publications, different shear cutting techniques, the near-net-shape-blanking processes (NNSBP’s), were investigated regarding a favorable residual stress state. The influence of the process parameters on the amount of clean cut, surface roughness, hardness and residual stresses was investigated. Furthermore, fatigue bending tests were carried out using C-shaped specimens. This paper reports about involute gears that are manufactured by fineblanking. This NNSBP was identified as suitable based on the previous research, because it led to a high amount of clean cut and favorable residual stresses. For the fineblanked gears of S355MC (1.0976), the die edge radii were varied and the effects on the cut surface geometry, hardness distribution, surface roughness and residual stresses are investigated. The accuracy of blanking the gear geometry is measured, and the tooth root bending strength is determined in a pulsating test rig according to standardized testing methods. It is shown that it is possible to manufacture gears by fineblanking with a high precision comparable to gear hobbing. Additionally, the cut surface properties lead to an increased tooth root bending strength.

EVALUATION OF SURFACE ROUGHNESS PRODUCED BY NANOCUTTING COPPER STRUCTURE USING A LEAST SQUARE MEAN METHOD

2019 ◽  
Vol 27 (01) ◽  
pp. 1950081 ◽  
Author(s):  
CHUNHUI JI ◽  
SHUANGQIU SUN ◽  
BIN LIN ◽  
TIANYI SUI
Keyword(s):  
Surface Roughness ◽  
Cutting Speed ◽  
Least Square ◽  
Depth Of Cut ◽  
Real Surface ◽  
Roughness Parameters ◽  
Machined Surface ◽  
Surface Roughness Parameters ◽  
3D Surface ◽  
3D Surface Roughness

This work performed molecular dynamic simulations to study the 2D profile and 3D surface topography in the nanometric cutting process. The least square mean method was used to model the evaluation criteria for the surface roughness at the nanometric scale. The result showed that the cutting speed was the most important factor influencing the spacing between the peaks, the sharpness of the peaks, and the randomness of the profile. The plastic deformation degree of the machined surface at the nanometric scale was significantly influenced by the cutting speed and depth of cut. The 2D and 3D surface roughness parameters exhibited a similar variation tendency, and the parameters Ra and Rq tended to increase gradually with an increase in the cutting speed and a decrease in the depth of cut. Finally, it is concluded that at the nanometric scale, the 3D surface roughness parameters could more accurately reflect the real surface characteristics than the 2D parameters.

Development of a PCD Burnishing Tool and its Burnishing Performance

2016 ◽  
Vol 874 ◽  
pp. 59-63
Author(s):  
Manabu Iwai ◽  
Masahide Yamada ◽  
Peter Chen ◽  
Bear Lin ◽  
Kiyoshi Suzuki
Keyword(s):  
Surface Roughness ◽  
Grain Size ◽  
Boron Doped Diamond ◽  
Machining Time ◽  
Electrically Conductive ◽  
Grain Sizes ◽  
Boron Doped ◽  
Steel Bar ◽  
Single Crystal Diamond ◽  
Composite Diamond

In this study, a polycrystalline composite diamond (PCD) was adopted instead of a single crystal diamond as a burnishing tool. At first, EDM machinability was compared between two kinds of PCDs (10μm grain size), i.e. standard PCD (S-PCD) and electrically conductive PCD (EC-PCD (which was made of boron doped diamond particles). EDM machining time to make a hemispherical shape was 17 minutes for EC-PCD and 37 minutes for S-PCD. Further experiments were conducted with EC-PCD of different grain sizes such as 2μm and 5μm. As a result, the smaller the grain size of EC-PCD the higher the machining efficiency was. Surface roughness values of the EC-PCD after finish EDM were Rz=1.7μm for EC-PCD010, Rz=1.4μm for EC-PCD005, and Rz=1.2μm for EC-PCD002. As a result of burnishing a carbon steel bar (S45C, φ30mm) with the EC-PCD tool, the surface roughness value after machining was improved from 10μm to 1μm.

Effects of Real Surface Roughness on Fluid Flow in Nanochannels

2010 ◽  
Author(s):  
Ali Kharazmi ◽  
Reza Kamali
Keyword(s):  
Molecular Dynamics ◽  
Surface Roughness ◽  
Fluid Flow ◽  
Computer Program ◽  
Md Simulation ◽  
Real Surface ◽  
Micro Channels

In the present study, a computer program based on a molecular dynamics scheme has been developed for simulating fluid flow in nano- and micro-channels with roughness. According to the previous studies of nanochannels flows, surface roughness has a great effect on the rheology of the flow. Therefore a more realistic surface roughness has been developed and its influence on the fluid flow has been investigated using Molecular Dynamics (MD) Simulation.

A unified theory of surface roughness

1984 ◽  
Vol 393 (1804) ◽  
pp. 133-157 ◽  
Keyword(s):  
Surface Roughness ◽  
Rough Surface ◽  
Random Noise ◽  
Sampling Interval ◽  
The Other ◽  
Real Surface ◽  
Unified Theory ◽  
Two Dimensional ◽  
Minor Degree ◽  
A Minor

The properties of the peaks and summits of a rough surface are predicted on the assumption that the surface is two-dimensional random noise. The important result is that, in non-dimensional form, the answers depend only to a minor degree on the parameters describing the surface or on the sampling interval used: on the other hand the absolute values are strongly dependent on the sampling interval. Experimental results on a real surface agree remarkably well with the predictions.

scholarly journals Land Cover Change Effects on the Climate of the La Plata Basin

2012 ◽  
Vol 13 (1) ◽  
pp. 84-102 ◽  
Author(s):  
Seung-Jae Lee ◽  
Ernesto Hugo Berbery
Keyword(s):  
Surface Roughness ◽  
Land Cover ◽  
Surface Temperature ◽  
River Basin ◽  
Land Surface ◽  
Roughness Length ◽  
Sensible Heat Flux ◽  
Near Surface ◽  
La Plata ◽  
Surface Roughness Length

Abstract Deforestation and replacement of natural pastures by agriculture have become a common practice in the La Plata River basin in South America. The changes in land cover imply changes in the biophysical properties of the land surface, with possible impacts on the basin’s hydroclimate. To help understand to what extent the climate could be affected, and through which processes, ensembles of seasonal simulations were prepared using the Weather Research and Forecasting Model for a control case and a scenario assuming an expansion of the agricultural activities to cover the entire basin. The La Plata River basin shows different climate responses to the land cover changes depending on the region. The northern part of the basin, where forests and savanna were replaced by crops, experiences an overall increase in albedo that leads to a reduction of sensible heat flux and near-surface temperature. A reduction of surface roughness length leads to stronger low-level winds that, in turn, favor a larger amount of moisture being advected out of the northern part of the basin. The result is a reduction of the vertically integrated moisture flux convergence (VIMFC) and, consequently, in precipitation. In the southern part of the basin, changes from grasslands to crops reduce the albedo and thus increase the near-surface temperature. The reduction in surface roughness length is not as large as in the northern sector, reducing the northerly moisture fluxes and resulting in a net increase of VIMFC and, thus, in precipitation. Notably, advective processes modify the downstream circulation and precipitation patterns over the South Atlantic Ocean.

Slip due to Rarefaction, Surface Roughness, and Intermolecular Interactions for Gases and Liquids

2011 ◽  
Author(s):  
Phil Ligrani
Keyword(s):  
Surface Roughness ◽  
Intermolecular Interactions ◽  
Stokes Equations ◽  
Slip Length ◽  
Wall Slip ◽  
Mean Free Path ◽  
Working Fluid ◽  
Channel Height ◽  
Near Surface ◽  
Accommodation Coefficients

In the present study, slip phenomena are investigated in two different sets of experiments conducted in gases and one Newtonian liquid. Overall, differences in near-surface slip behavior are illustrated for these two different fluid mediums, where the slip is induced surface roughness and rarefaction in the gases, and by surface roughness and intermolecular interactions in the liquid. Within both sets of experiments, flows are induced within micro-fluidic passages by rotation within C-shaped fluid chambers formed between a rotating disk and a stationary surface. When gases are employed, accommodation coefficients are determined in a unique manner from experimental results and analysis based on the Navier-Stokes equations. In all cases, roughness size is large compared to molecular mean free path. When channel height is defined at the tops of the roughness elements, slip is believed to be a result of rarefaction as well as fluid shear. With this arrangement, tangential accommodation coefficients decrease and slip velocity magnitudes increase, at a particular value of Knudsen number, as the level of surface roughness increases. With Newtonian water as the working fluid, hydrophobic roughness is used to induce near-wall slip in the fluid chamber. The magnitudes of slip length and slip velocities increase as the average size of the surface roughness becomes larger. The resulting slip length data show a high degree of organization when normalized using the fluid chamber height, such that experimental data obtained using different chamber heights and different disk roughness magnitudes collapse along a single line, illustrating strong linear dependence of the slip length on the normalized radial-line-averaged shear stress.

scholarly journals Effect of Surface Roughness on Oxidation Resistance of Stainless Steel AISI 316Ti During Exposure at High Temperature

2020 ◽  
Vol 29 (12) ◽  
pp. 8060-8069
Author(s):  
Wojciech J. Nowak
Keyword(s):  
Surface Roughness ◽  
Stainless Steel ◽  
Oxidation Resistance ◽  
Surface Preparation ◽  
Surface Region ◽  
Lower Surface ◽  
Near Surface ◽  
Steel Aisi ◽  
Kinetics Of ◽  
Effect Of Surface

AbstractIn the present work, the influence of surface roughness on oxidation kinetics of AISI 316Ti stainless steel and its consequences in term of oxidation resistance were investigated. Namely, the effect of surface roughness on oxidation resistance was evaluated during different types of cyclic oxidation tests at 900 and 1000 °C. The obtained results revealed that alloy possessing higher surface roughness showed longer lifetime compared to that with lower surface roughness. It was also found that more severe cyclic conditions suppressed the positive effect of surface roughness on sample’s lifetime. The better oxidation resistance of rougher alloy was correlated with suppressed formation of Fe-rich nodules on ground surfaces and explained by the combined effect of introduced defects in the near-surface region and possible increase in residual stresses caused by mechanical surface preparation.

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