Rolling Friction in MEMS Ball Bearings: The Effects of Loading and Solid Film Lubrication

2007 ◽  
Author(s):  
M. McCarthy ◽  
B. Hanrahan ◽  
C. Zorman ◽  
R. Ghodssi
Keyword(s):  
Contact Area ◽  
Ball Bearing ◽  
Sliding Friction ◽  
Rolling Resistance ◽  
Rolling Friction ◽  
Experimental Conditions ◽  
Solid Film ◽  
Frictional Forces ◽  
Film Lubrication

The effects of loading and solid film lubrication on rolling friction in MEMS-fabricated ball bearing structures are investigated in this paper. An in-situ non-contact experimental procedure was used to measure the frictional forces transmitted through a linear ball bearing system. The test devices consist of two silicon plates with deep-etched rectangular trenches acting as the housing for 285μm diameter steel microballs. The dynamic friction is measured with respect to relative velocity for several normal loads and it is observed that the frictional force increases linearly with microball contact area. Additionally, test structures with a 1μm silicon carbide (SiC) film deposited in the trenches have been tested. A 70% reduction in rolling resistance is shown between the nonlubricated and the SiC-lubricated test structures under identical experimental conditions. This is attributed to the reduced sliding friction in the SiC-steel contact area during interfacial slipping. To the best of our knowledge this is the first reported characterization of dynamic rolling friction in a MEMS device using a solid film lubricant. It is assumed that all frictional forces measured in this work are due to the desired rolling motion as well as bulk sliding of the microballs.

The Influence of Geometrical Parameters on the Friction Process in the Needle Bearing

2011 ◽  
Vol 490 ◽  
pp. 288-295
Author(s):  
Jerzy Nachimowicz ◽  
Robert Korbut
Keyword(s):  
Contact Area ◽  
Ball Bearing ◽  
Sliding Friction ◽  
Friction Pair ◽  
Rolling Friction ◽  
Geometrical Parameters ◽  
Friction Process ◽  
Motion Resistance ◽  
Initial Clearance ◽  
Analogical Process

The article analyses the process of friction in the needle bearing as the function of the alterations of geometrical parameters, namely the diameter of the shaft – D, the needle – d and the bearing clearance. The change in the relation between the diameters D and d results in the change of the contact area of the friction pair; in the case of two shafts with parallel axes (the needle of the bearing and the shaft pin) the contact area, if compared with the analogical process in the ball bearing, alters significantly and leads to resistance in motion. There are two types of friction in the needle bearing: the rolling friction and the sliding friction; the analysis of the movement of the bearing elements enabled the estimation of the extent to which the sliding friction matters in the overall balance of motion resistance. The article also defines the type of wear as the function of initial clearance.

Friction Studies on Rubberlike Materials

1960 ◽  
Vol 33 (5) ◽  
pp. 1218-1258 ◽  
Author(s):  
F. S. Conant ◽  
J. W. Liska
Keyword(s):  
Sliding Friction ◽  
Normal Force ◽  
Research Effort ◽  
Rolling Resistance ◽  
Surface Friction ◽  
Rolling Friction ◽  
Experimental Results ◽  
Solid Materials ◽  
Rubberlike Materials ◽  
Do So

Abstract One of the best summaries of the theory of friction between solid materials up to 1949 was published by Bowden and Tabor. However, little attention was devoted in this review to either theoretical or experimental results on the friction between rubberlike materials and other solids. In recent years, the literature on various aspects of the friction of rubberlike materials has become quite voluminous and unfortunately sometimes contradictory in the results and interpretations presented. This is understandable, to some extent, in the light of the fact that each individual research effort has usually been directed toward some particular aspect of the problem; certain, sometimes rather arbitrary, conditions are employed or assumed, and the results obtained are often rather unclear functions of these experimental or theoretical parameters. The situation is further complicated by the facts that at the very best, experimental frictional studies do not yield very accurate or readily reproducible data and the theories proposed, in many cases, are not subject to exact experimental verification. No comprehensive effort has been made, to date, to unify the various theories and to reconcile the conflicting experimental results on the friction of rubberlike materials and it is not the principal objective of the present review to do so. One of the aims is rather to report and summarize these sometimes divergent views in the hope that investigators in this field will be encouraged to study those areas in which knowledge is either inconclusive, contradictory or incomplete. Generally speaking, dynamic friction can be defined as the tangential reaction between two solids in relative motion in the presence of a normal force between the two solids. This definition can include both sliding and rolling friction. This review will be concerned principally with the sliding friction phase since rolling friction is generally conceded to be explained almost entirely by the internal friction of the deformable material. It has been stated, for example, that the rolling resistance of pneumatic tires at 80–95 mph is composed of 90–95% internal hysteresis, 2–10% surface friction and 1.5–3.5% air friction.

Traction of Elastohydrodynamic Contacts With Thermal Shearing Flow

1975 ◽  
Vol 97 (3) ◽  
pp. 424-428 ◽  
Author(s):  
J. Jakobsen ◽  
W. O. Winer
Keyword(s):  
Shear Stress ◽  
Thick Film ◽  
Contact Area ◽  
Rolling Friction ◽  
Shearing Flow ◽  
Flat Part ◽  
Design Charts ◽  
Inlet Region ◽  
Film Lubrication

The formulation and solution for the shear stress and temperature in heavily loaded sliding elastohydrodynamic contacts is presented. The solutions are presented in dimensionless design charts. Integration over the contact area will yield the traction. Accuracy is expected to be very good over the nearly flat part of the contact area where the majority of the sliding traction is generated. The procedure presented is not appropriate for thick film lubrication, for the inlet region, or for the rolling friction of elastohydrodynamic contacts.

The Friction of Hard Sliders on Lubricated Rubber: The Importance of Deformation Losses

1960 ◽  
Vol 33 (1) ◽  
pp. 129-141 ◽  
Author(s):  
J. A. Greenwood ◽  
D. Tabor
Keyword(s):  
Large Deformations ◽  
Sliding Friction ◽  
Hard Spheres ◽  
Water Film ◽  
Simple Calculation ◽  
Rolling Friction ◽  
Experimental Conditions ◽  
Hysteresis Losses ◽  
High Speeds ◽  
Rubber Surface

Abstract A study has been made of the friction of hard spheres and cones on a well lubricated rubber surface under conditions where relatively large deformations are produced. It is found that with spheres the sliding friction is almost the same as the rolling friction. Earlier work has shown that in the latter case the friction arises primarily from hysteresis losses in the rubber and it is concluded that, under the experimental conditions described, the main source of friction in lubricated sliding arises from the same cause. With conical sliders it is not possible to make a direct comparison with rolling experiments, but a simple calculation suggests that here again the friction is largely due to deformation losses in the rubber. For cones of small semi-angle there is a large increase in friction but this is associated with penetration of the lubricant film and tearing of the rubber. The friction results are in close agreement with measurements described by Miss Sabey for spheres and cones sliding on wet rubber at relatively high speeds (c. 6 ft sec−1). This suggests that in her experiments the water film provides very effective lubrication and that the friction arises largely from hysteresis losses in the rubber itself. As a general conclusion this study of the friction of lubricated rubber suggests that where interfacial adhesion is small and where relatively large local deformations occur the friction may well be dominated by deformation losses in the rubber. Under these conditions we may therefore expect the friction of hard spherical or conical sliders on rubber to be greater for rubbers of low Young's modulus and high hysteresis losses.

Thermomechanical Coupling of a Hyper-viscoelastic Truck Tire and a Pavement Layer and its Impact on Three-dimensional Contact Stresses

2021 ◽  
pp. 036119812110171
Author(s):  
Angeli Jayme ◽  
Imad L. Al-Qadi
Keyword(s):  
Contact Stress ◽  
Contact Area ◽  
Three Dimensional ◽  
Interaction Model ◽  
Rolling Resistance ◽  
Contact Stresses ◽  
Thermomechanical Coupling ◽  
Temperature Profiles ◽  
Near Surface ◽  
Truck Tire

A thermomechanical coupling between a hyper-viscoelastic tire and a representative pavement layer was conducted to assess the effect of various temperature profiles on the mechanical behavior of a rolling truck tire. The two deformable bodies, namely the tire and pavement layer, were subjected to steady-state-uniform and non-uniform temperature profiles to identify the significance of considering temperature as a variable in contact-stress prediction. A myriad of ambient, internal air, and pavement-surface conditions were simulated, along with combinations of applied tire load, tire-inflation pressure, and traveling speed. Analogous to winter, the low temperature profiles induced a smaller tire-pavement contact area that resulted in stress localization. On the other hand, under high temperature conditions during the summer, higher tire deformation resulted in lower contact-stress magnitudes owing to an increase in the tire-pavement contact area. In both conditions, vertical and longitudinal contact stresses are impacted, while transverse contact stresses are relatively less affected. This behavior, however, may change under a non-free-rolling condition, such as braking, accelerating, and cornering. By incorporating temperature into the tire-pavement interaction model, changes in the magnitude and distribution of the three-dimensional contact stresses were manifested. This would have a direct implication on the rolling resistance and near-surface behavior of flexible pavements.

The Brake Device Design for Children Two-Wheel Dynamic Scooter

2011 ◽  
Vol 421 ◽  
pp. 724-727
Author(s):  
Xue Feng Yi ◽  
Li Jun He
Keyword(s):  
Sliding Friction ◽  
Rolling Friction ◽  
Safety Performance ◽  
Device Design ◽  
Emergency Braking ◽  
Design For Children ◽  
Brake Device

Children scooter safety performance is not good enough in the market, the cause of the majority of injuries to children is difficult to control the speed or emergency braking. According to the phenomenon, this paper focuses on designing dynamic scooter brake device for 8-10 child, we conceive that the brake device is given the force of the rolling friction and the sliding friction, so it can play a dual brake effect. It will enhance the security and stability of children dynamic scooter.

In situ monitoring of isophorone diisocyanate-based flexible polyurethane foams formation

2016 ◽  
Vol 54 (1) ◽  
pp. 37-52 ◽  
Author(s):  
I Eceiza ◽  
L Irusta ◽  
A Barrio ◽  
MJ Fernández-Berridi
Keyword(s):  
Foam Height ◽  
Polyurethane Foams ◽  
In Situ Monitoring ◽  
Generation Process ◽  
Isophorone Diisocyanate ◽  
Experimental Conditions ◽  
Foaming Process ◽  
Foam Generation ◽  
Flexible Polyurethane

Novel isophorone diisocyanate-based flexible polyurethane foams were prepared by the one-step method in a computerized foam qualification system (FOAMAT). The experimental conditions to obtain this type of foams, in relation to the nature and concentration of catalysts as well as the reaction temperature, were established as no data were available in scientific literature. The chemical reactions occurring during the foam generation process were monitored in situ by attenuated total reflectance-FTIR spectroscopy. The kinetics of the foam generation was fitted to an nth order model and the data showed that the foaming process adjusted to a first-order kinetics. The physical changes as pressure, foam height, and dielectric polarization were monitored by the FOAM software (FOAMAT). According to these parameters, the foaming process was divided into four steps: bubble growth, bubble packing, cell opening, and final curing.

scholarly journals Estimation of real contact area during sliding friction from interface temperature

AIP Advances ◽  
2016 ◽  
Vol 6 (6) ◽  
pp. 065227
Author(s):  
Sung Keun Chey ◽  
Pengyi Tian ◽  
Yu Tian
Keyword(s):  
Contact Area ◽  
Sliding Friction ◽  
Real Contact Area ◽  
Interface Temperature ◽  
Real Contact

Parameter Study of Offset Press Cylinder Based on Sliding Friction

2010 ◽  
Vol 174 ◽  
pp. 299-302 ◽  
Author(s):  
Hai Yan Zhang ◽  
He Ping Hou ◽  
Jun Feng Si ◽  
Xiao Yu Chen
Keyword(s):  
Contact Area ◽  
Sliding Friction ◽  
Accurate Determination ◽  
Rolling Process ◽  
Elastic Cylinder ◽  
Parameter Study ◽  
Cylinder Radius ◽  
Printing Quality ◽  
Dot Gain

In the contact area of offset, a relative slide occurs between the surface of plate cylinder and blanket cylinder, which changes the print image and influences the printing quality. The relative slide in the cylinders’ rolling process is investigated, and the determination rule of cylinders’ geometric parameters of offset press is proposed. The results show that the relative slide is minimization under the condition that the compression of elastic cylinder radius is 0.2 times bigger than that of rigid cylinder radius, and the deformation of print image and dot gain both are minimization. The results provide theoretical direction for accurate determination of cylinder radius of offset press.

scholarly journals Application of an enzymatic cascade reaction for the synthesis of the emeraldine salt form of polyaniline

2021 ◽  
Author(s):  
Minoru Kurisu ◽  
Reinhard Kissner ◽  
Masayuki Imai ◽  
Peter Walde
Keyword(s):  
Cascade Reaction ◽  
Emeraldine Salt ◽  
Salt Form ◽  
Experimental Conditions ◽  
Peroxidase Isoenzyme ◽  
Large Unilamellar Vesicles ◽  
Dark Green ◽  
Catalyzed Oxidation ◽  
Reference Reaction

AbstractThe synthesis of the emeraldine salt form of polyaniline (PANI-ES) from aniline with Aspergillus sp. glucose oxidase (GOD), d-glucose, dissolved O2, and horseradish peroxidase isoenzyme C (HRPC) in the presence of large unilamellar vesicles of AOT (sodium bis-(2-ethylhexyl)sulfosuccinate) as templates at pH = 4.3 and T ~ 25 °C was investigated in a systematic way. In this cascade reaction mixture, the oxidation of aniline is catalyzed by HRPC with H2O2 that is formed in situ as byproduct of the GOD-catalyzed oxidation of d-glucose with O2. Under the elaborated experimental conditions which we considered ideal, the formation of PANI-ES products is evident, as judged by UV/Vis/NIR and EPR measurements. Comparison was made with a reference reaction, which was run under similar conditions with added H2O2 instead of GOD and d-glucose. Although the reference reaction was found to be superior, with the cascade reaction, PANI-ES products can still be obtained with high aniline conversion (> 90%) within 24 h as stable dark green PANI-ES/AOT vesicle dispersion. Our results show that the in situ formation of H2O2 does not prevent the inactivation of HRPC known to occur in the reference reaction. Moreover, the GOD used in the cascade reaction is inactivated as well by polymerization intermediates.

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