An Experimental Study of Grease in Elastohydrodynamic Lubrication

1972 ◽  
Vol 94 (1) ◽  
pp. 27-34 ◽  
Author(s):  
S. Y. Poon
Keyword(s):  
Experimental Study ◽  
High Temperature ◽  
Low Temperature ◽  
Elastohydrodynamic Lubrication ◽  
Time Dependent ◽  
Base Oil ◽  
Mineral Oils ◽  
Lubricating Film ◽  
Dependent Behavior ◽  
Inlet Zone

The formation of a lubricating film by grease in conditions pertinent to elastohydrodynamic lubrication is studied in a disk machine, and the thickness measured by means of a magnetic reluctance technique. The greases examined are three lithium hydroxystearate greases, of different soap structures and soap contents, a low temperature sodium-based grease, and a high temperature clay-based grease, all in mineral oils. The film thickness of greases in EHL differs from that of pure mineral oils in one important aspect: with one charge of the lubricant the thickness decreases continuously with time. The time-dependent behavior of greases is examined in relation to the thickener structure, viscosity of the base oil, and the conditions of the inlet zone.

scholarly journals The Unresolved Definition of The Pressure-Viscosity Coefficient

2021 ◽  
Author(s):  
Scott Bair
Keyword(s):  
High Temperature ◽  
Equation Of State ◽  
Low Temperature ◽  
Film Thickness ◽  
Pressure Dependence ◽  
Analytical Calculation ◽  
Elastohydrodynamic Lubrication ◽  
Viscosity Coefficient ◽  
Classical Approach ◽  
Definition Of

Abstract In the classical approach to elastohydrodynamic lubrication (EHL) a single parameter, the pressure-viscosity coefficient, quantifies the isothermal pressure dependence of the viscosity for use in prediction of film thickness. Many definitions are in current use. Progress toward a successful definition of this property has been hampered by the refusal of those working in classical EHL to acknowledge the existence of accurate measurements of the piezoviscous effect that have existed for nearly a century. The Hamrock and Dowson pressure-viscosity coefficient at high temperature requires knowledge of the piezoviscous response at pressures which exceed the inlet pressure and may exceed the Hertz pressure. The definition of pressure-viscosity coefficient and the assumed equation of state must limit the use of the classical formulas, including Hamrock and Dowson, to liquids with high Newtonian limit and to low temperature. Given that this problem has existed for at least fifty years without resolution, it is reasonable to conclude that there is no definition of pressure-viscosity coefficient that will quantify the piezoviscous response for an analytical calculation of EHL film thickness at temperatures above ambient.

Experimental Study on Combustion Characteristics of Three Biomass Components

2014 ◽  
Vol 953-954 ◽  
pp. 309-312
Author(s):  
Gui Qiu Su ◽  
Jian Yang ◽  
Hong Bo Lu
Keyword(s):  
Experimental Study ◽  
Weight Loss ◽  
High Temperature ◽  
Low Temperature ◽  
Combustion Process ◽  
Combustion Characteristics ◽  
Heating Rates ◽  
Biomass Components ◽  
Coke Combustion ◽  
Obvious Weight Loss

Experiments on combustion characteristics of cellulose, xylan and lignin have been done conducted on Pyris1 TGA thermograyimetric analyzer (PE/USA) at different heating rates. The results show that: combustion of cellulose was mainly concentrated in a low temperature range, xylan has two obvious weight loss peaks, while the lignin combustion mainly concentrated in a high temperature coke combustion process.

Time-Dependent Behavior of the Tunnels in Squeezing Ground: An Experimental Study

2021 ◽  
Vol 54 (4) ◽  
pp. 1755-1777
Author(s):  
Ketan Arora ◽  
Marte Gutierrez ◽  
Ahmadreza Hedayat ◽  
Erick Christian Cruz
Keyword(s):  
Experimental Study ◽  
Time Dependent ◽  
Squeezing Ground ◽  
Dependent Behavior

Experimental Study on Time-Dependent Behavior of Cracked UHP-FRCC Under Sustained Loads

2016 ◽  
pp. 101-109 ◽  
Author(s):  
Tomoya Nishiwaki ◽  
Sukmin Kwon ◽  
Hiroto Otaki ◽  
Go Igarashi ◽  
Faiz U.A. Shaikh ◽  
...  
Keyword(s):  
Experimental Study ◽  
Time Dependent ◽  
Dependent Behavior ◽  
Sustained Loads

Experimental Study on Two-Stage Cascade Low Temperature Pre-Cooling Equipment

2010 ◽  
Vol 42 ◽  
pp. 322-325
Author(s):  
Xiu Fang Liu ◽  
Fa Hui Wang ◽  
Fan Mao Meng
Keyword(s):  
Experimental Study ◽  
High Temperature ◽  
Low Temperature ◽  
Cooling Capacity ◽  
Temperature Cycle ◽  
Test Bed ◽  
Two Stage ◽  
Overload Protection ◽  
Set Up ◽  
Two Stages

A two-stage cascade pre-cooling test bed was designed and set up to develop a -30°C /-60°C pre-cooling equipment. An internal heater exchanger and a condenser were set in low-temperature cycle. Theoretically the two stages can work stably at setting temperature and the low-temperature cycle can operate independently with aided starting of the high-temperature cycle. The experimental results indicate that the test bed can provide cooling capacity steadily at -46°C and -100°C respectively and the low-temperature cycle cannot operate alone for compressor overload protection. Based on the analysis, the possible reasons and detailed suggestions were put forward.

Cadmium substitution in miargyrite (AgSbS2) and related phases: an experimental reconnaissance

1996 ◽  
Vol 60 (400) ◽  
pp. 393-401 ◽  
Author(s):  
I. Kelleher ◽  
S. A. T. Redfern ◽  
R. A. D. Pattrick
Keyword(s):  
Experimental Study ◽  
High Temperature ◽  
Low Temperature ◽  
Unit Cell ◽  
Monoclinic Distortion ◽  
High Temperature Polymorph

AbstractAn experimental study of cadmium substitution into AgXS2 phases (X = As, Bi, Sb) indicates significant amounts of cadmium can be incorporated in the structure by the mechanism 2Cd ⇌ Ag + X. The limit of substitution of Cd in the high-temperature polymorph of miargyrite, β-AgSbS2 is 6.2 at.%, whereas the low-temperature polymorph, α-AgSbS2, can accommodate at least 12 at.% cadmium. Substitution of Cd into the cubic β-AgSbS2 induces a small monoclinic distortion and the unit cell becomes pseudo-cubic. The α ⇌ β transition in Cd-substituted miargyrites is modified by the solute ions, with both a reduction of Tc and transition smearing evident. Similar effects are also recorded in Cd-substituted AgAsS2 and AgBiS2.

A Design Approach for Correlating High Temperature Fatigue Crack Growth Over a Wide Range of Parameters

1981 ◽  
Vol 103 (3) ◽  
pp. 246-252 ◽  
Author(s):  
J. J. McGowan ◽  
H. W. Liu
Keyword(s):  
Fatigue Crack ◽  
High Temperature ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Behavior ◽  
Load Ratio ◽  
Time Dependent ◽  
High Temperature Fatigue ◽  
Dependent Behavior ◽  
Cycle Dependent

High temperature fatigue crack growth was studied in several materials under various environmental conditions. At temperatures less than one-half of the melting point, creep effects were found to be negligible in comparison to environmental effects. The general fatigue behavior is a result of both time dependent and cycle dependent processes. A model is formulated which combines linearly the separate time and cycle dependent behaviors to correlate the general fatigue behavior. The cycle dependent behavior in the model is based upon the premise that the relative corrosion rate controls the crack growth rate. The few constants in the cycle dependent portion of the model are based upon the fatigue crack growth in the environment with zero load ratio and no dwell. The time dependent behavior is determined from static crack growth data in the environment. The resulting Kinetic Model correlates with good success the effects of temperature, frequency, dwell time and load ratio on the high temperature air fatigue crack growth of IN-100.

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