Biomechanical Measurements: Pedestrian Coefficient of Friction

2009 ◽  
pp. 124-124-9
Author(s):  
BE Gray ◽  
RD Jablonsky ◽  
H Yoshida
Keyword(s):  
Coefficient Of Friction ◽  
Biomechanical Measurements

An Analytical Thermodynamic Approach to Friction of Rubber on Ice

2012 ◽  
Vol 40 (2) ◽  
pp. 124-150
Author(s):  
Klaus Wiese ◽  
Thiemo M. Kessel ◽  
Reinhard Mundl ◽  
Burkhard Wies
Keyword(s):  
Coefficient Of Friction ◽  
Liquid Layer ◽  
Contact Area ◽  
Leading Edge ◽  
Viscous Friction ◽  
Analytical Approximation ◽  
Real Contact Area ◽  
Length Scales ◽  
Real Contact ◽  
Ice Surface

ABSTRACT The presented investigation is motivated by the need for performance improvement in winter tires, based on the idea of innovative “functional” surfaces. Current tread design features focus on macroscopic length scales. The potential of microscopic surface effects for friction on wintery roads has not been considered extensively yet. We limit our considerations to length scales for which rubber is rough, in contrast to a perfectly smooth ice surface. Therefore we assume that the only source of frictional forces is the viscosity of a sheared intermediate thin liquid layer of melted ice. Rubber hysteresis and adhesion effects are considered to be negligible. The height of the liquid layer is driven by an equilibrium between the heat built up by viscous friction, energy consumption for phase transition between ice and water, and heat flow into the cold underlying ice. In addition, the microscopic “squeeze-out” phenomena of melted water resulting from rubber asperities are also taken into consideration. The size and microscopic real contact area of these asperities are derived from roughness parameters of the free rubber surface using Greenwood-Williamson contact theory and compared with the measured real contact area. The derived one-dimensional differential equation for the height of an averaged liquid layer is solved for stationary sliding by a piecewise analytical approximation. The frictional shear forces are deduced and integrated over the whole macroscopic contact area to result in a global coefficient of friction. The boundary condition at the leading edge of the contact area is prescribed by the height of a “quasi-liquid layer,” which already exists on the “free” ice surface. It turns out that this approach meets the measured coefficient of friction in the laboratory. More precisely, the calculated dependencies of the friction coefficient on ice temperature, sliding speed, and contact pressure are confirmed by measurements of a simple rubber block sample on artificial ice in the laboratory.

TOUGHMET 2CX

Alloy Digest ◽  
2013 ◽  
Vol 62 (6) ◽  
Keyword(s):  
Tensile Strength ◽  
Wear Resistance ◽  
Corrosion Resistance ◽  
Physical Properties ◽  
Tensile Properties ◽  
Coefficient Of Friction ◽  
Loading Conditions ◽  
Severe Loading

Abstract ToughMet 2 CX is a Cu-9Ni-6Sn alloy that combines low coefficient of friction with wear resistance. ToughMet alloys are a line of spinodal hardened Cu-Ni antigalling alloys for bearings capable of performing with a variety of shafting materials and lubricants. The alloys combine a high lubricity with wear resistance in these severe loading conditions. ToughMet 2CX in the cast and spinodally hardened (CX) condition exhibits tensile strength in excess of 724 MPa (105 ksi) and hardness exceeding HRC 27 with excellent machinability. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming. Filing Code: Cu-819. Producer or source: Materion Brush Performance Alloys.

Experimental Investigation of aluminum doping crumb rubber/epoxy composite in reciprocating motion

2015 ◽  
Vol 3 ◽  
pp. 1
Author(s):  
Goutam Chandra Karar ◽  
Nipu Modak
Keyword(s):  
Experimental Investigation ◽  
Coefficient Of Friction ◽  
Epoxy Composite ◽  
Normal Load ◽  
Crumb Rubber ◽  
The Other ◽  
Reciprocating Motion ◽  
Molding Process ◽  
Friction Tester ◽  
The Coefficient Of Friction

The experimental investigation of reciprocating motion between the aluminum doped crumb rubber /epoxy composite and the steel ball has been carried out under Reciprocating Friction Tester, TR-282 to study the wear and coefficient of frictions using different normal loads (0.4Kg, 0.7Kgand1Kg), differentfrequencies (10Hz, 25Hz and 40Hz).The wear is a function of normal load, reciprocating frequency, reciprocating duration and the composition of the material. The percentage of aluminum presents in the composite changesbut the other components remain the same.The four types of composites are fabricated by compression molding process having 0%, 10%, 20% and 30% Al. The effect of different parameters such as normal load, reciprocating frequency and percentage of aluminum has been studied. It is observed that the wear and coefficient of friction is influenced by the parameters. The tendency of wear goes on decreasing with the increase of normal load and it is minimum for a composite having 10%aluminum at a normal load of 0.7Kg and then goes on increasing at higher loads for all types of composite due to the adhesive nature of the composite. The coefficient of friction goes on decreasing with increasing normal loads due to the formation of thin film as an effect of heat generation with normal load.

Designing of Outriggers for the Needs of the Vehicles Stability Testing

2018 ◽  
Vol 875 ◽  
pp. 71-76
Author(s):  
Victor Kryaskov ◽  
Andrey Vashurin ◽  
Anton Tumasov ◽  
Alexey Vasiliev
Keyword(s):  
Coefficient Of Friction ◽  
Computer Aided Design ◽  
Strength Analysis ◽  
Direct Impact ◽  
Stability Testing ◽  
Supporting Surface ◽  
Stability Tests ◽  
Computer Aided ◽  
Aided Design

This paper is dedicated to the issues of designing of outriggers for avoidance of vehicle tilting during its stability tests. An analysis of existing types of outriggers was done by authors as well as legislative requirements on them. The reliable and well-timed operation of outriggers largely depends on the height of their positioning on a vehicle. In order to determine this important parameter a special methodic of determining the tipping angle of the vehicle with the use of computer-aided design (CAD) was composed by authors. The article also contains some main principles of strength analysis of the structure a very important part of which became the necessity of determination of coefficient of friction between the outrigger sliders and the supporting surface. This coefficient has a direct impact on the value of transverse forces appearing at the ends of outrigger beams.

scholarly journals Biomechanical Measurement of Rabbit Cornea by a Modified Scheimpflug Device

2016 ◽  
Vol 2016 ◽  
pp. 1-6
Author(s):  
Bo Zhang ◽  
Jianjun Gu ◽  
Xiaoxiao Zhang ◽  
Bin Yang ◽  
Zheng Wang ◽  
...  
Keyword(s):  
Bulk Modulus ◽  
Correlation Coefficient ◽  
Intraclass Correlation Coefficient ◽  
Intraclass Correlation ◽  
Anterior Segment ◽  
Intraobserver Reliability ◽  
Rabbit Cornea ◽  
Deformation Response ◽  
Biomechanical Measurements ◽  
Biomechanical Measurement

Purpose. To explore the probability and variation in biomechanical measurements of rabbit cornea by a modified Scheimpflug device.Methods. A modified Scheimpflug device was developed by imaging anterior segment of the model imitating the intact eye at various posterior pressures. The eight isolated rabbit corneas were mounted on the Barron artificial chamber and images of the anterior segment were taken at posterior pressures of 15, 30, 45, 60, and 75 mmHg by the device. The repeatability and reliability of the parameters including CCT, ACD, ACV, and CV were evaluated at each posterior pressure. All the variations of the parameters at the different posterior pressures were calculated.Results. All parameters showed good intraobserver reliability (Cronbach’s alpha; intraclass correlation coefficient,α, ICC > 0.96) and repeatability in the modified Scheimpflug device. With the increase of posterior pressures, the ratio of CCT decreased linearly and the bulk modulus gradually reduced to a platform. The increase of ACD was almost linear with the posterior pressures elevated.Conclusions. The modified Scheimpflug device was a valuable tool to investigate the biomechanics of the cornea. The posterior pressure 15–75 mmHg range produced small viscoelastic deformations and nearly linear pressure-deformation response in the rabbit cornea.

scholarly journals Evaluation of Intraocular Pressure and Other Biomechanical Parameters to Distinguish between Subclinical Keratoconus and Healthy Corneas

2021 ◽  
Vol 10 (9) ◽  
pp. 1905
Author(s):  
Cristina Peris-Martínez ◽  
María Amparo Díez-Ajenjo ◽  
María Carmen García-Domene ◽  
María Dolores Pinazo-Durán ◽  
María José Luque-Cobija ◽  
...  
Keyword(s):  
Function Theory ◽  
Rank Test ◽  
Maximum Deformation ◽  
Corrected Visual Acuity ◽  
Signed Rank ◽  
Signed Rank Test ◽  
Biomechanical Parameters ◽  
Spss Software ◽  
Biomechanical Measurements ◽  
Noncontact Tonometry

(1) Purpose: To assess the main corneal response differences between normal and subclinical keratoconus (SCKC) with a Corvis® ST device. (2) Material and Methods: We selected 183 eyes of normal patients, of a mean age of 33 ± 9 years and 16 eyes of patients with SCKC of a similar mean age. We measured best corrected visual acuity (BCVA) and corneal topography with a Pentacam HD device to select the SCKC group. Biomechanical measurements were performed using the Corvis® ST device. We carried out a non-parametric analysis of the data with SPSS software (Wilcoxon signed rank-test). (3) Results: We found statistically significant differences between the control and SCKC groups in some corneal biomechanical parameters: first and second applanation time (p = 0.05 and p = 0.02), maximum deformation amplitude (p = 0.016), highest concavity radius (p = 0.007), and second applanation length and corneal velocity ((p = 0.039 and p = 0.016). (4) Conclusions: Our results show that the use of normalised biomechanical parameters provided by noncontact tonometry, combined with a discriminant function theory, is a useful tool for detecting subclinical keratoconus.

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