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Article
Publication date: 14 September 2015

Linlin Li, Jiajun Yang and Wenwei Liu

The purpose of this paper is to explore the effect of surface roughness characterized by fractal geometry on squeeze film damping characteristics in damper of the linear rolling…

Abstract

Purpose

The purpose of this paper is to explore the effect of surface roughness characterized by fractal geometry on squeeze film damping characteristics in damper of the linear rolling guide, which has not been studied so far.

Design/methodology/approach

The stochastic model of film thickness between rail and damper is established by using the two-variable Weierstrass–Mandelbrot function defining multi-scale and self-affinity properties of the rough surface topography. The stochastically averaged Reynolds equation is solved by using the variables separation method to further derive the film pressure distribution, the damping coefficient, the damping force and squeeze film time. The effect of surface roughness on squeeze film damping characteristics of the damper is analyzed and discussed through simulation.

Findings

By comparing cases of the rough surface for different fractal parameters and the smooth surface, it is shown that for the isotropic roughness structure, the presence of surface roughness of the damper decreases the squeeze film damping characteristics. It is found that roughness effect on the damping coefficient is associated with the film thickness. In addition, the vibration amplitude effect is negligible for the damper of the linear rolling guide.

Originality/value

To investigate the random surface roughness effect, the rough surface topography of damper of the linear rolling guide is characterized by using the fractal method instead of the traditional mathematical statistics method.

Details

Industrial Lubrication and Tribology, vol. 67 no. 6
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 1 September 1997

Jacques Masounave, Youssef A. Youssef, Yves Beauchamp and Marc Thomas

Investigates the effects of the most influential cutting parameters (cutting speed, feed rate, depth of cut, tool nose radius, tool length and work piece length) on surface

1800

Abstract

Investigates the effects of the most influential cutting parameters (cutting speed, feed rate, depth of cut, tool nose radius, tool length and work piece length) on surface roughness quality and on the formation of built‐up edge in a lathe dry turning process of mild carbon steel samples. A full factorial design (384 experiments), taking into account the three‐level interactions between the independent variables has been conducted. The results show that the following three‐level interactions: feed rate × cutting speed × depth of cut, feed rate × cutting speed × tool nose radius and tool nose radius × depth of cut × tool length have significant effects on surface roughness in this type of machining operation. Shows that the analysis of main effects alone and even two‐level interactions could lead to a false interpretation of the results. The analysis of variance revealed that the best surface roughness is achieved with a low feed rate, a large tool nose radius and a high cutting speed. The results also show that the depth of cut has no significant effect on surface roughness when operating at cutting speeds higher than 160m/min. Furthermore, it is shown that built‐up edge formation deteriorates surface roughness when machining mild carbon steel at specific feed rate, tool nose radius and cutting speed levels. Proposes a new model for evaluating the limiting cutting speed to avoid the built‐up edge formation. Finally, shows through experimentation that an increase in depth of cut would lead to improved surface roughness when tool vibration is increased.

Details

International Journal of Quality Science, vol. 2 no. 3
Type: Research Article
ISSN: 1359-8538

Keywords

Article
Publication date: 1 May 2006

Y. Zhang

To develop a more realistic model for molecularly thin film hydrodynamic lubrication by incorporating the fluid inhomogeneity and discontinuity effects across the fluid film…

Abstract

Purpose

To develop a more realistic model for molecularly thin film hydrodynamic lubrication by incorporating the fluid inhomogeneity and discontinuity effects across the fluid film thickness in this lubrication.

Design/methodology/approach

The total mass flow of the fluid through the contact in a basic one‐dimensional molecularly thin film hydrodynamic lubrication is studied by incorporating the fluid inhomogeneity and discontinuity effects across the fluid film thickness, based on a simplified momentum transfer model between neighboring fluid molecules across the fluid film thickness. This flow is calculated according to the present approach and the theory of viscous flow between two contact surfaces. The total mass flow of the fluid through the contact in this lubrication is also calculated from conventional hydrodynamic lubrication theory, which was based on continuum fluid assumption in the whole lubricated contact. The ratio of this flow calculated from the present approach to that calculated from conventional hydrodynamic lubrication theory is here defined as the flow factor for a one‐dimensional molecularly thin film hydrodynamic lubrication due to the fluid inhomogeneity and discontinuity effects. Results of this flow factor are presented for wide operational parameters.

Findings

In the molecularly thin film hydrodynamic lubrication, when the fluid inhomogeneity and discontinuity across the fluid film thickness both are incorporated, the total fluid mass flow through the contact and thus the global fluid film thickness are increased. The combined effect of the fluid inhomogeneity and discontinuity across the fluid film thickness on the total fluid mass flow through the contact in this lubrication is determined by the operational parameter K=((∂p/∂xh2)/[6ηbulk(1−ξ)(ua+ub)]); when the operational parameter K is high, this effect is significant; when the operational parameter K is low, this effect is negligible. On the other hand, in this lubrication, when the combined effect of the fluid inhomogeneity and discontinuity across the fluid film thickness is incorporated, the shear stresses at the contact‐fluid interfaces are reduced and this reduction can be significant. This reduction may strongly depend on the value of the dimensionless discontinuity parameter Δ/D of the fluid across the fluid film thickness but weakly depend on the number n of the fluid molecules across the fluid film thickness.

Practical implications

An important and very useful research for the academic researcher and the engineer who are, respectively, engaged in the study and design of hydrodynamic lubrication on mechanical components especially of very low hydrodynamic lubrication film thickness. It is also important to the subsequent research of molecularly thin film hydrodynamic lubrication.

Originality/value

A new model of molecularly thin film hydrodynamic lubrication in one‐dimensional contacts is originally proposed and described by incorporating the fluid inhomogeneity and discontinuity effects across the fluid film thickness in this lubrication. This new model of molecularly thin film hydrodynamic lubrication is of importance to the theoretical study of molecularly thin film hydrodynamic lubrication.

Details

Industrial Lubrication and Tribology, vol. 58 no. 3
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 23 October 2023

Markus Groth and Mahsa Esmaeilikia

This paper aims to aims to extend emotional labor research by exploring whether the impact of emotional labor on customer satisfaction depends on the order in which different…

Abstract

Purpose

This paper aims to aims to extend emotional labor research by exploring whether the impact of emotional labor on customer satisfaction depends on the order in which different emotional labor strategies are used by employees. Specifically, the authors explore how the order effects of two emotional labor strategies – deep and surface acting – impact customer satisfaction.

Design/methodology/approach

The authors conducted two experimental studies in which participants interacted with service employees who systematically switched between surface and deep acting strategies during the service episode. In Study 1, participants watched a video clip depicting a service encounter in a bookstore. In Study 2, participants partook in a simulated career-counseling session.

Findings

The four different emotional labor strategy order effects differentially impact customer satisfaction. Consistent with theories of gain–loss effects, improvement and decline trends positively or negatively impact customers, respectively. Furthermore, results show that these trends impact customer satisfaction growth differently over time.

Research limitations/implications

The authors only focused on two emotional labor strategies, and future research may benefit from extending the research to additional regulation strategies and/or specific discrete emotions.

Practical implications

The results suggest that managers may train employees in recognizing that customer satisfaction is not just driven by customers’ overall assessment of the interaction but also by their experience at different stages of the interaction.

Originality/value

Service marketing and management scholars have largely explored emotional labor from a between-person or within-person perspective, with little empirical attention paid to within-episode processes that focus on how employee behavior varies within a single service episode. To the best of the authors’ knowledge, this study is one of the first to demonstrate that surface and deep acting can be used simultaneously and dynamically over the course of a single service interaction in impacting customer satisfaction.

Details

European Journal of Marketing, vol. 57 no. 12
Type: Research Article
ISSN: 0309-0566

Keywords

Abstract

Details

The Handbook of Road Safety Measures
Type: Book
ISBN: 978-1-84855-250-0

Article
Publication date: 15 April 2022

Mohamed Abd Alsamieh

The purpose of this study is to investigate the combined effect of surface force, solvation and Van der Waals forces and surface topography parameters of amplitude and wavelength…

Abstract

Purpose

The purpose of this study is to investigate the combined effect of surface force, solvation and Van der Waals forces and surface topography parameters of amplitude and wavelength on the formation of ultrathin films for elastohydrodynamic lubrication of point contact problems.

Design/methodology/approach

The Newton–Raphson technique is used to simultaneously solve the Reynolds’ film thickness including surface roughness and elastic deformation, surface force of solvation and Van der Waals forces and load balance equations. Different values of surface amplitude and wavelength were simulated in addition to the load variation.

Findings

The simulation results revealed that roughness effects are important as the film thickness decreases. The oscillation in the pressure and film thickness is due to the combined action of the solvation force and surface topography parameters. The limiting values of the surface topography parameters of the amplitude and wavelength varied and depended on the load. For different values of wavelength and load, amplitude values up to 0.25 nm have no effect on ultrathin film formation.

Originality/value

The combined effect of the surface force and surface roughness on the formation of ultrathin films was evaluated for elastohydrodynamic lubrication of point contact problems under different operating conditions of load and surface topography parameters of amplitude and wavelength. The limited surface topography parameters of the amplitude and wavelength are shown and analyzed.

Details

Industrial Lubrication and Tribology, vol. 74 no. 6
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 31 July 2019

Dandan Qiu, Lei Luo, Songtao Wang, Bengt Ake Sunden and Xinhong Zhang

This study aims to focus on the surface curvature, jet to target spacing and jet Reynolds number effects on the heat transfer and fluid flow characteristics of a slot jet…

Abstract

Purpose

This study aims to focus on the surface curvature, jet to target spacing and jet Reynolds number effects on the heat transfer and fluid flow characteristics of a slot jet impinging on a confined concave target surface at constant jet to target spacing.

Design/methodology/approach

Numerical simulations are used in this research. Jet to target spacing, H/B is varying from 1.0 to 2.2, B is the slot width. The jet Reynolds number, Rej, varies from 8,000 to 40,000, and the surface curvature, R2/B, varies from 4 to 20. Results of the target surface heat transfer, flow parameters and fluid flow in the concave channel are performed.

Findings

It is found that an obvious backflow occurs near the upper wall. Both the local and averaged Nusselt numbers considered in the defined region respond positively to the Rej. The surface curvature plays a positive role in increasing the averaged Nusselt number for smaller surface curvature (4-15) but affects little as the surface curvature is large enough (> 15). The thermal performance is larger for smaller surface curvature and changes little as the surface curvature is larger than 15. The jet to target spacing shows a negative effect in heat transfer enhancement and thermal performance.

Originality/value

The surface curvature effects are conducted by verifying the concave surface with constant jet size. The flow characteristics are first obtained for the confined impingement cases. Then confined and unconfined slot jet impingements are compared. An ineffective point for surface curvature effects on heat transfer and thermal performance is obtained.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 8
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 10 August 2012

Jaw‐Ren Lin

On the ground of the Hopf bifurcation theory derived by Hassard et al., the purpose of this paper is to investigate the weakly nonlinear dynamics of transverse rough‐surface short…

Abstract

Purpose

On the ground of the Hopf bifurcation theory derived by Hassard et al., the purpose of this paper is to investigate the weakly nonlinear dynamics of transverse rough‐surface short journal bearings.

Design/methodology/approach

By application of the stochastic model of rough surfaces, developed by Christensen and Tonder, the roughness effects of transverse surface patterns on the bifurcation behaviors close to the Hopf bifurcation point are investigated.

Findings

It is found that the dynamic behavior of transverse rough‐surface short journal bearings can display Hopf bifurcation phenomena. Comparing with the case of isotropic rough‐surface bearing by Lin, under the same parameters, the effects of transverse surface roughness provide a reduced sub‐critical Hopf bifurcation region as well as an increased super‐critical Hopf bifurcation region. In addition, the effects of transverse surface roughness result in a lower stability‐threshold critical speed for both the sub‐critical bifurcation profile and the super‐critical bifurcation profile.

Originality/value

The present study, associated with the results of Hopf bifurcation regions and periodic orbits, can provide useful information for engineers when the transverse surface roughness effects and the bifurcation behavior are considered in a journal bearing system.

Details

Industrial Lubrication and Tribology, vol. 64 no. 5
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 1 February 2013

M. Mahbubur Razzaque and Muhannad Mustafa

The purpose of this paper is to present a parametric study of the effects of permeability and surface roughness on the hydrodynamic force and the leakage flow rate in an…

Abstract

Purpose

The purpose of this paper is to present a parametric study of the effects of permeability and surface roughness on the hydrodynamic force and the leakage flow rate in an oscillating squeeze film between a rigid surface and a rubber surface.

Design/methodology/approach

The study is conducted numerically using a squeeze film model that incorporates the effects of viscoelasticity, permeability and surface roughness.

Findings

It is seen that with increasing permeability of the porous rubber block, both the hydrodynamic force and the leakage flow rate decrease. Increasing center line average (CLA) of surface roughness height distribution decreases the leakage flow rate slightly but increases the hydrodynamic force. The decrease in the hydrodynamic force due to using permeable material in squeeze film may be compensated for by deliberately increasing the surface roughness. The effect of variation in frequency of system vibration may be minimized by using optimally selected permeable materials with rough surface.

Originality/value

The paper reports the extension of previous work of the authors and the results of this portion were never published. The findings of this paper are based on original work and have practical value.

Details

Industrial Lubrication and Tribology, vol. 65 no. 1
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 6 June 2023

Mohamed Abd Alsamieh

The purpose of this paper is to investigate the performance of an ultra-thin film lubricated conjunction through the elastohydrodynamic lubrication of point contacts for various…

Abstract

Purpose

The purpose of this paper is to investigate the performance of an ultra-thin film lubricated conjunction through the elastohydrodynamic lubrication of point contacts for various ridge shapes and sizes located within the contact zone including flat-top, triangle and cosine wave profiles, considering the influence of surface forces of solvation and Van der Waals’ in addition to the hydrodynamic effect to predict an optimum geometric characteristics for surface texture for lubricated conjunctions.

Design/methodology/approach

Surface features are simulated in a variety of sizes and shapes including flat-top, triangle and cosine wave profiles. While estimating the elastic deformation of the contacting surfaces, surface forces of solvation and Van der Waals’ are taken into account. The Reynolds equation is solved using the Newton–Raphson method to get the pressure profile and film thickness including the elastic deformation, and surface feature.

Findings

The geometrical characteristics of the ridge, its placement in relation to the contact zone and its height all have a significant impact on the performance of ultra-thin film lubricated conjunction. When the triangular-shaped ridge is present in contact, it forecasts even sharper peaks in film thickness and pressure. More friction, wear and eventually contact fatigue are brought on by this more acute pressure and film thickness peaks. The flat-top ridge shape shows a better performance for lubricated conjunction where, the minimum film thickness value is comparable to that obtained for the case of a smooth contact surface. This behavior is attributed to the effect of intermolecular force of solvation. An increase in the size of the ridge results in a step increase in the film thickness for different ridge shapes, particularly for the flat-topped ridge pattern.

Originality/value

Evaluation of the performance of elastohydrodynamic lubricated ultra-thin film conjunction related to film thickness and pressure profile for various ridge surface features of different amplitudes, shapes and sizes located through the contact zone considering the influence of surface forces of solvation and Van der Waals’ in addition to the hydrodynamic effect.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2023-0062/

Details

Industrial Lubrication and Tribology, vol. 75 no. 5
Type: Research Article
ISSN: 0036-8792

Keywords

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