Effects of Elastic Moduli of Contact Surfaces in Elastohydrodynamic Lubrication

1992 ◽  
Vol 114 (1) ◽  
pp. 75-80 ◽  
Author(s):  
M. Kaneta ◽  
H. Nishikawa ◽  
K. Kameishi ◽  
T. Sakai ◽  
N. Ohno
Keyword(s):  
Elastic Moduli ◽  
Elastohydrodynamic Lubrication ◽  
Tangent Plane ◽  
Squeeze Film ◽  
Entrainment Velocity ◽  
Squeeze Film Effect ◽  
Contact Surfaces ◽  
The Difference ◽  
Surface Deflections ◽  
Film Profile

Using the optical interferometry technique the film profile in circular elastohydrodynamic contacts is examined with several kinds of fluid under wide ranges of loads and speeds. It is found that under a sliding condition a deep conical depression (dimple) occurs in the contact surface in place of the flat plateau predicted by the EHL theory. This dimple phenomena can be explained by the squeeze film effect acting parallel to the contact plane attributable to the difference in surface deflections of the contact bodies. That is, if the contacting bodies are different in their elastic moduli, EHL film shape is markedly influenced by the slide/roll ratio even if the rolling or entrainment velocity is kept constant. This result suggests that the establishment of a new EHL theory, which takes into consideration the effects of the difference in elastic moduli of the contacting surfaces and surface pressure components parallel to the contact tangent plane, is necessary for deeper understanding of the EHL regime.

Numerical Study on the Interaction of Transverse and Longitudinal Roughness on Elastohydrodynamic Lubrication Contact Surfaces With Different Thermal Conductivities and Elastic Moduli

2020 ◽  
Vol 143 (9) ◽  
Author(s):  
Motohiro Kaneta ◽  
Kenji Matsuda ◽  
Jing Wang ◽  
Jinlei Cui ◽  
Peiran Yang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Finite Length ◽  
Elastic Moduli ◽  
Elastohydrodynamic Lubrication ◽  
High Thermal Conductivity ◽  
Low Thermal Conductivity ◽  
Longitudinal Roughness ◽  
Transverse Roughness ◽  
Contact Surfaces ◽  
Thermal Conductivities

Abstract The interaction and surface features between point contact surfaces composed of longitudinal roughness with infinite or finite length and transverse roughness were discussed based on a transient non-Newtonian thermal elastohydrodynamic lubrication (EHL) model. Each surface shape is greatly affected by the difference in elastic moduli, thermal conductivities, and velocities of both contact surfaces. There is a large difference in pressure behavior when the transverse roughness is in contact with the longitudinal roughness with finite length and when it is in contact with the longitudinal roughness with infinite length. In the contact between surfaces with infinitely long longitudinal and transverse roughness, the friction coefficient is lower when the surface with longitudinal roughness has a low thermal conductivity than when it has a high thermal conductivity. Furthermore, the pressure fluctuation is larger when the transverse roughness surface has a high thermal conductivity than when it has a low thermal conductivity.

The Causes of Asymmetric Deformation of Surface Roughness Asperities in EHL Contacts

2021 ◽  
pp. 1-38
Author(s):  
Motohiro Kaneta ◽  
Kenji Matsuda ◽  
Hiroshi Nishikawa
Keyword(s):  
Thermal Conductivity ◽  
Surface Roughness ◽  
Contact Pressure ◽  
Elastic Moduli ◽  
Elastohydrodynamic Lubrication ◽  
The Other ◽  
Contact Materials ◽  
Oil Film ◽  
Asymmetric Deformation ◽  
The Difference

Abstract This paper provides the main causes of asymmetric or directional deformation of surface roughness based on a transient non-Newtonian thermal elastohydrodynamic lubrication (EHL) model, where the contact materials have different thermal conductivities and elastic moduli. It is clarified that the asymmetric deformation of the asperities appears due to two causes. One depends on the slide-roll ratio and the difference in thermal conductivity between contact materials, and the other is caused by the contact pressure between the asperities through the oil film.

Finite Element Analysis of Creep Damage Behavior Near the Cavity on Bimaterial Interface

2006 ◽  
Vol 324-325 ◽  
pp. 951-954 ◽  
Author(s):  
Qing Min Yu ◽  
Zhu Feng Yue ◽  
Yong Shou Liu
Keyword(s):  
Finite Element ◽  
Elastic Moduli ◽  
Elastic Stress ◽  
Creep Damage ◽  
Ductile Material ◽  
Bimaterial Interface ◽  
Modulus Ratio ◽  
Element Analysis ◽  
Damage Law ◽  
The Difference

Fracture along an interface between materials plays a major role in failure of material. In this investigation, finite element calculations with Kachanov–Rabotnov damage law were carried out to study the creep damage distribution near the interface cavity in bimaterial specimens. The specimens with central hole were divided into three types. The material parameters of K-R law used in this paper were chosen for a brittle material and ductile material. All calculations were performed under four load cases. Due to the difference between elastic moduli of the bounded materials, the elastic stress field as a function of the Young’s modulus ratio (R=E1/E2) was determined. At the same time, the influence of model type on elastic stress distribution near the cavity was considered. Under the same conditions, the material with larger modulus is subjected to larger stress. The creep damage calculations show that the location of the maximum damage is different for each model. The distributions of creep damage for all three models are dependent on the material properties and load cases.

Thermal Elastohydrodynamic Lubrication Analysis for Point Contact Transmission

2009 ◽  
Author(s):  
Hai-zhou Huang ◽  
Xi-chuan Niu ◽  
Xiao-yang Yuan
Keyword(s):  
Film Thickness ◽  
Numerical Solutions ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Surface Velocity ◽  
Squeeze Film ◽  
Elastic Displacement ◽  
Circular Arc ◽  
Tooth Width ◽  
Contact Transmission

To investigate the thermal EHL (elastohydrodynamic lubrication) in point contact transmission, a model considering the two-dimensional surface velocity of tooth face and the running-in is proposed. The numerical solutions for pressure, temperature and film thickness distribution in the contact zone are obtained by solving equations including the Reynolds, Energy and the elastic displacement with variable dimension meshing method. The model was used to study the point contact transmission of the circular arc gear in a windlass. The main results show that it is pure rolling along the direction of tooth width, and the rolling speed plays a leading role in improving the lubricating performance and transmission efficiency of circular arc gear. The squeeze film effect makes the pressure peak tend to be gentle and the film thickness increase slightly.

Observation of Wall Slip in Elastohydrodynamic Lubrication

1990 ◽  
Vol 112 (3) ◽  
pp. 447-452 ◽  
Author(s):  
M. Kaneta ◽  
H. Nishikawa ◽  
K. Kameishi
Keyword(s):  
Experimental Technique ◽  
Elastohydrodynamic Lubrication ◽  
Wall Slip ◽  
Optical Interferometry ◽  
Stepping Motor ◽  
Ehd Lubrication ◽  
Pure Rolling ◽  
Direct Indication ◽  
Contact Surfaces ◽  
Oil Films

A new experimental technique using optical interferometry has been developed to obtain a direct indication of non-Newtonian response of an oil film under conditions of elastohydrodynamic (EHD) lubrication. A glass disk or a steel ball has been driven by a stepping motor so that crescent-shaped thick oil films with undulation in thickness along the direction of motion have been generated. The experiments have been carried out under pure rolling and pure sliding conditions. It has been found that the oil in an EHD contact behaves like a solid and slips at or near the contact surfaces.

Cuticle sclerotization determines the difference between the elastic moduli of locust tibiae

2020 ◽  
Vol 103 ◽  
pp. 189-195 ◽  
Author(s):  
Chuchu Li ◽  
Stanislav N. Gorb ◽  
Hamed Rajabi
Keyword(s):  
Elastic Moduli ◽  
Cuticle Sclerotization ◽  
The Difference

Rod Control Assemblies Wear Mechanisms

2002 ◽  
Author(s):  
Damien Kaczorowski ◽  
Jean-Mary Georges ◽  
Sandrine Bec ◽  
Andre´-Bernard Vannes ◽  
Andre´ Tonck ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Squeeze Film ◽  
Third Body ◽  
Body Effect ◽  
Principal Role ◽  
Squeeze Film Effect ◽  
Steel Surfaces ◽  
Contact Pressures ◽  
Tubular Components

In nuclear power plants, slender tubular components are subjected to vibrations in a PHTW environment. As a result, the two contacting surfaces, tubes and their guides undergo impact at low contact pressures [1]. The components are usually made of stainless steel and it was found that the influence of the PHTW, combined with other actions (such as corrosion, erosion, squeeze film effect, third body effect and cavitation) leads to a particular wear of the material [2] [3]. Therefore, this paper aims to show that the colloidal oxides, formed on the steel surfaces in PHTW, play a principal role in the wear of the surfaces. Actually, due to the specific kinematic conditions of the contact, the flow of compacted oxides abrades the surfaces.

The Effect of Shape and Distribution of Perforations on Squeeze-Film Damping in Parallel Plate Capacitors

2009 ◽  
Author(s):  
Weili Cui ◽  
Ronald N. Miles ◽  
Dorel Homentcovsci
Keyword(s):  
Parallel Plate ◽  
Internal Heat ◽  
Optical Switches ◽  
Squeeze Film ◽  
Mems Devices ◽  
Capacitive Sensing ◽  
Squeeze Film Damping ◽  
Squeeze Film Effect ◽  
Capacitive Mems ◽  
Stationary Plate

The effect of the shape and distribution of perforations in parallel plate capacitive MEMS devices on squeeze-film damping is presented. The squeeze film effect is the most important damping effect on the dynamic behavior of most MEMS devices that employ capacitive sensing and actuation, which typically employ narrow air gaps between planar moving surfaces [1, 2]. The stationary plate of a capacitive device is often perforated to reduce the damping and sensor noise and improve the frequency response. The formula for determining the total viscous damping in the gap contains a coefficient Cp that is associated with the geometry and distribution of the holes on the stationary plate. In this study, the coefficient Cp is determined using the finite element method using ANSYS by analogy with heat conduction in a solid with internal heat generation. Round, elliptical, rectangular, and oval holes that are distributed either aligned or offset are analyzed and compared. It is shown that the surface fraction occupied by the perforations is not the only factor that determines Cp. Both the shape and distribution strongly affect the damping coefficient [3, 4]. By using elongated perforations that are properly distributed, the squeeze film damping could be minimized with the minimum amount of perforation. The analysis performed in this work is quite general being applicable to a very large spectrum of frequencies and to various fluids in capacitive sensors. These results can facilitate the design of mechanical structures that utilize capacitive sensing and actuation, such as accelerometers, optical switches, micro-torsion mirrors, resonators, microphones, etc.

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