An Investigation on Starvation Onset of Rough Surface Line Contacts

2021 ◽  
pp. 1-20
Author(s):  
Sheng Li ◽  
Ali Kolivand ◽  
Anusha Anisetti
Keyword(s):  
Surface Roughness ◽  
Normal Force ◽  
Force Density ◽  
Rolling Velocity ◽  
Response Parameter ◽  
Line Contacts ◽  
Roughness Amplitude ◽  
Critical Film Thickness ◽  
Influential Parameters ◽  
Lubricant Viscosity

Abstract Utilizing a computational approach, this study quantifies the onset of lubrication starvation for line contacts of rough surfaces operating under typical ranges of automotive gearing applications. The response parameter is selected as the critical film thickness supply, at which starvation initiates. The potential influential parameters (predictors) considered include normal force density, rolling velocity, sliding, lubricant viscosity, and surface roughness amplitude. A non-Newtonian thermal mixed lubrication model is employed to determine the critical lubricant supply under various operating and surface roughness conditions. General linear regression is implemented to reach an easy-to-use equation (R-squared value higher than 97%), facilitating the quantification of starvation dependence on the predictors that are statistically significant.

The behaviour of heavily loaded line contacts with transverse roughness

1999 ◽  
Vol 213 (4) ◽  
pp. 309-320 ◽  
Author(s):  
C. J. Hooke
Keyword(s):  
Surface Roughness ◽  
Full Range ◽  
Numerical Results ◽  
Operating Conditions ◽  
Entrainment Velocity ◽  
Original Surface ◽  
Line Contacts ◽  
Transverse Roughness ◽  
Inlet Length

In heavily loaded, piezoviscous contacts the surface roughness tends to be flattened inside the conjunction by any relative sliding of the surfaces. However, before it is flattened, the roughness affects the inlet to the contact, producing clearance variations there. These variations are then convected through the contact, at the entrainment velocity, producing a clearance distribution that differs from the original surface. The present paper explores this behaviour and establishes how the amplitude of the convected clearance varies with wavelength and operating conditions. It is shown that the primary influence is the ratio of the wavelength to the inlet length of the conjunction. Where this ratio is large, the roughness is smoothed and there is little variation in clearance under the conjunction. Where the ratio is small, significant variations in clearance may occur but the precise amplitude and phasing depend on the ratio of slide to roll velocities and on the value of a piezoviscous parameter, c. The numerical results agree closely with existing solutions but extend these to cover the full range of operating conditions.

scholarly journals Effect of Water-Based Nanolubricants in Ultrasonic Vibration Assisted Grinding

2018 ◽  
Vol 2 (4) ◽  
pp. 80 ◽  
Author(s):  
Mir Molaie ◽  
Ali Zahedi ◽  
Javad Akbari
Keyword(s):  
Surface Roughness ◽  
Specific Energy ◽  
Material Removal ◽  
Normal Force ◽  
Tangential Force ◽  
Process Efficiency ◽  
Multiwall Carbon Nanotube ◽  
Ultrasonic Vibrations ◽  
Mql Grinding ◽  
Water Based

Currently, because of stricter environmental standards and highly competitive markets, machining operations, as the main part of the manufacturing cycle, need to be rigorously optimized. In order to simultaneously maximize the production quality and minimize the environmental issues related to the grinding process, this research study evaluates the performance of minimum quantity lubrication (MQL) grinding using water-based nanofluids in the presence of horizontal ultrasonic vibrations (UV). In spite of the positive impacts of MQL using nanofluids and UV which are extensively reported in the literature, there is only a handful of studies on concurrent utilization of these two techniques. To this end, for this paper, five kinds of water-based nanofluids including multiwall carbon nanotube (MWCNT), graphite, Al2O3, graphene oxide (GO) nanoparticles, and hybrid Al2O3/graphite were employed as MQL coolants, and the workpiece was oscillated along the feed direction with 21.9 kHz frequency and 10 µm amplitude. Machining forces, specific energy, and surface quality were measured for determining the process efficiency. As specified by experimental results, the variation in the material removal nature made by ultrasonic vibrations resulted in a drastic reduction of the grinding normal force and surface roughness. In addition, the type of nanoparticles dispersed in water had a strong effect on the grinding tangential force. Hybrid Al2O3/graphite nanofluid through two different kinds of lubrication mechanisms—third body and slider layers—generated better lubrication than the other coolants, thereby having the lowest grinding forces and specific energy (40.13 J/mm3). It was also found that chemically exfoliating the graphene layers via oxidation and then purification prior to dispersion in water promoted their effectiveness. In conclusion, UV assisted MQL grinding increases operation efficiency by facilitating the material removal and reducing the use of coolants, frictional losses, and energy consumption in the grinding zone. Improvements up to 52%, 47%, and 61%, respectively, can be achieved in grinding normal force, specific energy, and surface roughness compared with conventional dry grinding.

Effect of Rolling Velocity and Maximum Hertzian Pressure on Fluid Film in Steady State EHL Line Contact with Rough Surface and Linear Piezoviscosity

2014 ◽  
Vol 592-594 ◽  
pp. 1371-1375
Author(s):  
Nitesh Talekar ◽  
Punit Kumar
Keyword(s):  
Surface Roughness ◽  
Steady State ◽  
Film Thickness ◽  
Rough Surface ◽  
Computer Code ◽  
Fluid Film ◽  
Line Contact ◽  
Rolling Velocity ◽  
Load Carrying ◽  
Lubricated Contact

Consideration of surface roughness in steady state EHL line contact is the first step towards understanding the lubrication of rough surface problem. Current paper investigates the use of sinusoidal waviness in the contact; more precisely it gives performance of real fluid in EHL line contact. The effect of various parameters like rolling velocity (U) and maximum Hertzian pressure (ph) on surface roughness by using properties of linear and exponential piezo-viscosity is taken into consideration to evaluate behavior of pressure distribution of load carrying fluid film and film thickness. Full isothermal, Newtonian simulation of EHL problem gives described effects. Spiking or fluctuation of pressure and film thickness curves is expected to show presence of irregularities on the surface chosen and amount of fluctuation depends on certain parameters and intensity of irregularities present. Rolling side domain of-4.5 ≤ X ≤ 1.5 with grid size ∆X=0.01375 is selected. A computer code is developed to solve Reynolds equation, which governs the generation of pressure in the lubricated contact zone is discritized and solved along with load balance equation using Newton-Raphson technique.

Simulation of Plasto-Elastohydrodynamic Lubrication in Line Contacts of Infinite and Finite Length

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Tao He ◽  
Jiaxu Wang ◽  
Zhanjiang Wang ◽  
Dong Zhu
Keyword(s):  
Surface Roughness ◽  
Finite Length ◽  
3D Model ◽  
Three Dimensional ◽  
Elastohydrodynamic Lubrication ◽  
Axial Direction ◽  
Contact Length ◽  
Line Contact ◽  
Line Contacts ◽  
3D Surface Topography

Line contact is common in many machine components, such as various gears, roller and needle bearings, and cams and followers. Traditionally, line contact is modeled as a two-dimensional (2D) problem when the surfaces are assumed to be smooth or treated stochastically. In reality, however, surface roughness is usually three-dimensional (3D) in nature, so that a 3D model is needed when analyzing contact and lubrication deterministically. Moreover, contact length is often finite, and realistic geometry may possibly include a crowning in the axial direction and round corners or chamfers at two ends. In the present study, plasto-elastohydrodynamic lubrication (PEHL) simulations for line contacts of both infinite and finite length have been conducted, taking into account the effects of surface roughness and possible plastic deformation, with a 3D model that is needed when taking into account the realistic contact geometry and the 3D surface topography. With this newly developed PEHL model, numerical cases are analyzed in order to reveal the PEHL characteristics in different types of line contact.

Contact Mechanics of a Hard Cylinder on a Viscoelastic Layer

Tribology ◽  
2006 ◽  
Author(s):  
Steven R. H. Barrett ◽  
Alexander H. Slocum
Keyword(s):  
Pressure Distribution ◽  
Contact Mechanics ◽  
Normal Force ◽  
Maxwell Model ◽  
Sliding Contact ◽  
Viscoelastic Layer ◽  
Tractive Force ◽  
Rolling Velocity ◽  
One Dimensional ◽  
The One

The rolling/sliding contact of a hard cylinder on a viscoelastic layer is re-examined. The one-dimensional Maxwell model, with the addition of a parallel spring, is used to model the normal stiffness of the viscoelastic layer A solution for the pressure distribution is presented. It is shown that the maximum tractive force that the cylinder can sustain before complete sliding is a function of the sense and magnitude of the rolling velocity. Two regimes of loading are considered - constant cylinder normal force and constant cylinder indentation.

Investigation of Grinding Force and Surface Integrity of IC10 in Creep Feed Grinding

2020 ◽  
Author(s):  
Jun-chen Li ◽  
Wen-hu Wang ◽  
Rui-song Jiang ◽  
Xiao-fen Liu ◽  
Huang Bo ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Tool Wear ◽  
Material Removal ◽  
Normal Force ◽  
Removal Rate ◽  
Tangential Force ◽  
Grinding Force ◽  
Wheel Speed ◽  
Creep Feed Grinding ◽  
Creep Feed

Abstract The IC10 superalloy material is one of the most important materials for aero-engine turbine blade due to its excellent performances. However, it is difficult to be machined because of its special properties such as terrible tool wear and low machined efficiency. The creep feed grinding is widely used in machining IC10 superalloy due to the advance in reducing tool wear, improving material removal rate and surface quality. The creep feed grinding is a promising machining process with the advantages of high material removal rate due to large cutting depth, long cutting arc and very slow workpiece, and its predominant features might have significant influence on the grinding force and surface quality for the workpiece. Hence, it is of great importance to study the grinding force and surface integrity in creep feed grinding IC10 superalloy. In this paper, a series of orthogonal experiments have been carried out and the effects of grinding parameters on the grinding force and the surface roughness are analyzed. The topographies and defects of the machined surface were observed and analyzed using SEM. The results of the experiments show that the tangential force is decreased with the workpiece speed increasing. However, there is no significant change in tangential force with the increasing of grinding depth and wheel speed. The normal force is decreased with the workpiece speed increasing when the workpiece speed is less than 150 mm/min, but when the workpiece speed is more than 150 mm/min the normal force is increased tardily. Moreover, the normal force is increased sharply with the increase of grinding depth and is increased slowly with the increase of wheel speed. In general, the surface roughness is increased with workpiece speed and grinding depth increasing, while the trend of increase corresponding that of workpiece speed is more evident. The value of the surface roughness is decreased with wheel speed increasing. And it is found out that the main defect is burning of the IC10 superalloy material in creep feed grinding by energy spectrum analysis of some typical topography in this study.

Electron Mobility due to Surface Roughness Scattering in Depleted GaAs Free-Standing Thin Ribbon

2019 ◽  
Vol 954 ◽  
pp. 51-59
Author(s):  
Xi Duo Hu ◽  
Cheng Ming Li ◽  
Shao Yan Yang
Keyword(s):  
Surface Roughness ◽  
Quantum Well ◽  
Electron Mobility ◽  
Atomic Scale ◽  
Free Standing ◽  
Poisson Equations ◽  
Surface Roughness Scattering ◽  
Calculation Results ◽  
Roughness Amplitude ◽  
Dimensional Electron Gas

Abstract:Electron mobility limited by surface roughness scattering in free-standing GaAs thin ribbon with an internal parabolic quantum well caused by surface state is investigated in detail. Based on analyzing the parabolic quantum well including the energy subband level, wave function and the confined potential profile in the thin ribbon by solving Schrödinger and Poisson equations self-consistently, the electron mobility could be investigated. Conclusion indicates that remote surface roughness (RSR) of the thin ribbon will change the two dimensional electron gas (2DEG) mobility through the medium of barrier height fluctuation of the parabolic well in atomic scale. Calculation results reveal that the 2DEG mobility decreases with increasing roughness amplitude, which is characterized in terms of the surface roughness height and the roughness lateral size.

scholarly journals A note on the effect of surface topography on adhesion of hard elastic rough bodies with low surface energy

2019 ◽  
Vol 28 (1) ◽  
pp. 8-12 ◽  
Author(s):  
Guido Violano ◽  
Giuseppe Demelio ◽  
Luciano Afferrante
Keyword(s):  
Surface Roughness ◽  
Surface Energy ◽  
Adhesive Contact ◽  
Low Surface Energy ◽  
Surface Gradient ◽  
Self Consistent ◽  
Remarkable Result ◽  
Roughness Amplitude ◽  
Adhesive Interactions ◽  
Effect Of Surface

AbstractAdhesion between bodies is strongly influenced by surface roughness. In this note, we try to clarify how the statistical properties of the contacting surfaces affect the adhesion under the assumption of long-range adhesive interactions.Specifically, we show that the adhesive interactions are influenced only by the roughness amplitude hrms, while the rms surface gradient h0rmsonly affects the non-adhesive contact force. This is a remarkable result if one takes into account the intrinsic difficulty in defining $h_{\mathrm{rms}}^{^{\prime }}.$Results are also corroborated by a comparison with self-consistent numerical calculations.

An Investigation of the Impacts of Contact Parameters on Wear Coefficient

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
V. Janakiraman ◽  
S. Li ◽  
A. Kahraman
Keyword(s):  
Surface Roughness ◽  
Point Contact ◽  
Viscosity Coefficient ◽  
Rolling Contact ◽  
Wear Coefficient ◽  
Wear Process ◽  
Contact Formulation ◽  
Model Combining ◽  
Roughness Amplitude ◽  
Disk Rolling

In this study, the wear depths under different loads, speeds, lubricant temperatures, and surface roughness amplitudes are experimentally determined using a twin-disk rolling contact setup. A point contact wear model combining a contact formulation and Archard's wear equation in an iterative manner is developed to simulate the wear process of the experiments. By matching the measured and predicted wear profiles, the wear coefficients under different operating and surface conditions are determined. It is found that the wear coefficient increases when either the load or the surface roughness amplitude increases and decreases as the lubricant pressure-viscosity coefficient increases. Within the operating ranges considered, it is observed that the lubricant pressure-viscosity coefficient is the most influential parameter on wear, the load has the least impact, and the surface roughness amplitude is in between. Lastly, a regression formula is given for the estimation of Archard's wear coefficient.

Investigation of Friction Over a Wide Range of Normal Forces

2007 ◽  
Author(s):  
Dirk Drees ◽  
Satish Achanta
Keyword(s):  
Surface Roughness ◽  
Dual Phase Steel ◽  
Normal Force ◽  
Diamond Like Carbon ◽  
Dual Phase ◽  
Normal Forces ◽  
Atomic Force ◽  
Wide Range ◽  
Atomic Interactions ◽  
The Coefficient Of Friction

Friction at different force, length, and time scales is of great interest in tribology. The mechanical, chemical, and physical (atomic) interactions, each operating at their own time length and force scale, makes friction complex. This work is an attempt to improve the understanding of friction at normal forces ranging from nN up to N. This investigation was carried out under reciprocating ball-on-flat sliding conditions on engineering surfaces like diamond-like carbon (DLC) and dual phase steel. The test equipments used for this investigation are an atomic force microscope, a microtribometer, and a macrofretting tester. It was observed that for a hard/hard tribocouple like DLC/Si3N4, the variation in the coefficient of friction is negligible whereas the variation is large when the tribocouple is hard / soft like in dual phase steel / Si3N4. By changing the surface roughness of the material, the dependence of friction on normal force could be altered or manipulated.

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