scholarly journals Friction and temperature mapping of environmentally acceptable gear oils

2020 ◽  
Vol 37 (3−4) ◽  
Author(s):  
Reza Bayat ◽  
Arto Lehtovaara
Keyword(s):  
Elastohydrodynamic Lubrication ◽  
Environmental Issues ◽  
Mineral Oils ◽  
Oil Performance ◽  
Small Test ◽  
The Common ◽  
Gear Contact ◽  
Gear Oils ◽  
Temperature Maps ◽  
Ball On Disc

In recent years, environmental issues have raised the demand to protect the environment against the pollution caused by the uncontrolled spillage of lubricating oils. One solution is using Environmentally Acceptable Lubricants (EALs), however, these oils are more expensive than the common mineral oils. The consumers require to test the oil performance using test machines but testing in real machines is costly and time-consuming. Small test machines like ball-on-disc have been previously used for friction mapping and ranking gear oils. In this paper, the friction maps are measured from 0.65 GPa to 1.25 GPa, and temperature maps are devised to experimentally simulate the gear contact along the line of action. Results illustrate that EALs can provide up to 60 % better frictional efficiency that leads to 20 oC cooler oil temperature in high-pressure contacts operating under elastohydrodynamic lubrication (EHL) regime.

Isolation and characterization of oleochemical compounds from watermelon seed

2020 ◽  
Vol 10 (4) ◽  
pp. 79-82
Author(s):  
Madhubhushan M ◽  
Seshaiah S ◽  
Chandrudu J ◽  
Sagar R ◽  
Akila CR
Keyword(s):  
Cutting Tool ◽  
Citrullus Lanatus ◽  
Fatty Esters ◽  
Mineral Oils ◽  
Light Yellow ◽  
Isolation And Characterization ◽  
The Common ◽  
Set Up ◽  
Natural Gradation

The common watermelon item (Citrullus lanatus) seeds were gained from castoffs verdant nourishments for use by decorating, sun ventilation and pulverizing. Light yellow-toned oil was gotten by dissolvable withdrawal using oil atmosphere and the going with traits were gotten using oil ether: pH, refractive rundown, thickness, dissolvable miscibility, coagulating temperature, fire nature, express gravity, streak point and warmth of consuming. With a shallow level of unsaturation, stepped level of smoothness, and proximity of raised degree of the sensible proportion of free unsaturated fats. The low assessment of the solidifying temperature of the oil offered a hint that the oil can be managed in various areas paying little heed to the qualification in temperature. The following level of linoleic destructive of the oil offers a hint of natural gradation of solidarity. Fatty esters are increasing expanding significance as a biodegradable swap for mineral oils. In some request regions, for example, cutting tool oil, gearbox, pressure-driven oils, and greases for raw petroleum creation, the oleochemical items are set up. Nonetheless, certain particular wellsprings of fatty esters are hitherto to be abused for this comparative reason. This exploration subsequently tests into one of the less used wellsprings of fatty esters in watermelon. The oil from the kernels demonstrations a top-notch yield presents significant utilitarian gatherings for change and thus was utilized to set up an assortment of oleochemicals which demonstrated excellence materials in contrast with the routinely utilized oils feed frameworks for oleochemicals after portrayal. The photopolymers acquired indicated piercing vinyl protons for consistent polymerize.

scholarly journals A thermal resistances-based approach for thermal-elastohydrodynamic calculations in point contacts

2017 ◽  
Vol 232 (11) ◽  
pp. 2088-2102 ◽  
Author(s):  
Eduardo de la Guerra Ochoa ◽  
Javier Echávarri Otero ◽  
Enrique Chacón Tanarro ◽  
Benito del Río López
Keyword(s):  
Friction Coefficient ◽  
Film Thickness ◽  
Thermal Effects ◽  
Good Accuracy ◽  
Computational Cost ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Point Contacts ◽  
New Approach ◽  
Ball On Disc

This article presents a thermal resistances-based approach for solving the thermal-elastohydrodynamic lubrication problem in point contact, taking the lubricant rheology into account. The friction coefficient in the contact is estimated, along with the distribution of both film thickness and temperature. A commercial tribometer is used in order to measure the friction coefficient at a ball-on-disc point contact lubricated with a polyalphaolefin base. These data and other experimental results available in the bibliography are compared to those obtained by using the proposed methodology, and thermal effects are analysed. The new approach shows good accuracy for predicting the friction coefficient and requires less computational cost than full thermal-elastohydrodynamic simulations.

Effects of out-of-contact lubricant channeling on friction and film thickness in starved elastohydrodynamic lubrication point contacts

2016 ◽  
Vol 231 (4) ◽  
pp. 432-440 ◽  
Author(s):  
Fadi Ali ◽  
Ivan Křupka ◽  
Martin Hartl
Keyword(s):  
Film Thickness ◽  
Digital Camera ◽  
Elastohydrodynamic Lubrication ◽  
Contact Condition ◽  
Friction Reduction ◽  
Rolling Element Bearings ◽  
Point Contacts ◽  
Practical Applications ◽  
Rolling Element ◽  
Ball On Disc

This study presents experimental results on the effect of out-of-contact lubricant channeling on the tribological performance of nonconformal contacts under starved lubrication. Channeling of lubricant was carried out by adding a slider with a limited slot for scraping the displaced lubricant on one of mating surfaces (ball). Thus, the scraped lubricant is forced to flow back into the depleted track through the limited slot resulting in robust replenishment. The measurements have been conducted using optical tribometer (ball-on-disc) equipped with a digital camera and torque sensor. The effect of lubricant channeling was compared to the original contact condition by means of measuring friction and film thickness. The results show that the out-of-contact lubricant channeling leads to a significant enhancement of film thickness and friction reduction under starved conditions. Indeed, the starved elastohydrodynamic lubrication contacts transformed to the fully flooded regime after introducing the flow reconditioning. Moreover, the film thickness decay over time, which is common with starved elastohydrodynamic lubrication contacts, has not been observed in the case of lubricant channeling. However, the beneficial effect of lubricant channeling diminishes as the original contact condition tends to the fully flooded regime. The results of this study can be easily implemented in practical applications such as radial and thrust rolling-element bearings.

scholarly journals The correlation between gear contact friction and ball on disc friction measurements

2015 ◽  
Vol 83 ◽  
pp. 114-119 ◽  
Author(s):  
M. Björling ◽  
J. Miettinen ◽  
P. Marklund ◽  
A. Lehtovaara ◽  
R. Larsson
Keyword(s):  
Contact Friction ◽  
Friction Measurements ◽  
Gear Contact ◽  
Ball On Disc

scholarly journals Elastohydrodynamics of a Worm Gear Contact

2000 ◽  
Vol 123 (2) ◽  
pp. 268-275 ◽  
Author(s):  
S. Kong ◽  
K. Sharif ◽  
H. P. Evans ◽  
R. W. Snidle
Keyword(s):  
Film Thickness ◽  
Three Dimensional ◽  
Elastohydrodynamic Lubrication ◽  
Worm Gear ◽  
Simulation Technique ◽  
Elastic Contact ◽  
Gear Teeth ◽  
Film Forming ◽  
Worm Gears ◽  
Gear Contact

The paper is concerned with prediction of elastic contact and elastohydrodynamic film thickness in worm gears. Using the undeformed geometry of the gap between gear teeth in contact a three-dimensional elastic contact simulation technique has been developed for calculation of the true area of elastic contact under load relative to the wheel and worm surfaces. A parallel investigation of elastohydrodynamic lubrication effects has been carried out using a special non-Newtonian, thermal solver which takes account of the nonsymmetrical and spin aspects of worm contacts. An interesting feature of the results obtained is the discovery of regions of poor film forming due to entrainment failure at the edges of the contact.

scholarly journals Pearls in Mitigating Application Pain of Topical Nonsteroidal Agents

Dermatology ◽  
2020 ◽  
Vol 236 (5) ◽  
pp. 477-480 ◽  
Author(s):  
Steven Madsen ◽  
Kyla N. Price ◽  
Vivian Y. Shi ◽  
Peter A. Lio
Keyword(s):  
Adverse Effect ◽  
Therapeutic Option ◽  
Topical Steroid ◽  
Test Area ◽  
Application Site ◽  
Inflammatory Dermatoses ◽  
Small Test ◽  
The Common ◽  
Site Pain ◽  
Steroid Sparing

Background: Topical steroid-sparing agents (SSA), such as tacrolimus, pimecrolimus, and crisaborole, represent an important therapeutic option in the treatment of inflammatory dermatoses such as atopic dermatitis. While these agents lack the common side effects associated with topical corticosteroids, they all share application site pain as an important adverse effect. Summary: Based on the available evidence and our experience, we suggest the following 7 practical strategies for decreasing the pain associated with SSA use. (1) Use a topical corticosteroid for a few days to reduce inflammation before starting the SSA treatment. (2) Use SSAs strategically. (3) Apply moisturizer before applying SSAs. (4) Store moisturizers in the refrigerator. (5) Ask the patient to apply the SSA on a small test area before broader application. (6) Apply the SSA on dry rather than on damp skin. (7) Consider using aspirin when appropriate for the patient.

scholarly journals Alumina-Toughened-Zirconia with Low Wear Rate in Ball-on-Flat Tribological Tests at Temperatures to 500 °C

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7646
Author(s):  
Marek Grabowy ◽  
Kamil Wojteczko ◽  
Agnieszka Wojteczko ◽  
Grzegorz Wiązania ◽  
Maciej Łuszcz ◽  
...  
Keyword(s):  
Wear Rate ◽  
Tetragonal Zirconia ◽  
Commercial Alumina ◽  
Strongly Connected ◽  
The Common ◽  
Low Wear ◽  
Zirconia Powders ◽  
Better Than ◽  
Sem Analyses ◽  
Ball On Disc

An alumina-toughened zirconia (ATZ) material, fabricated using a procedure consisting of the common sintering of two different zirconia powders, was tested using the ball-on-disc method in a temperature range between room temperature and 500 °C. Corundum balls were used as a counterpart. The ATZ composite behaviour during tests was compared with that of commonly used α-alumina and tetragonal zirconia sintered samples. At temperatures over 350 °C, a drastic decrease in the wear rate of the material was detected. SEM analyses proved that, in such conditions, nearly the whole surface of the sliding material was covered with a layer of deformed submicrometric grains, which limited contact with the part of material that was not deformed. The mentioned layer was relatively strongly connected with the material, increased its resistance, and decreased its coefficient of friction. As a reference, commonly used materials, namely commercial alumina and tetragonal zirconia, were tested. The wear parameters of the composite were significantly better than those registered for the materials prepared of commercial powders.

Elastohydrodynamic lubrication at high pressures

1978 ◽  
Vol 360 (1702) ◽  
pp. 403-425 ◽  
Keyword(s):  
Shear Modulus ◽  
Film Thickness ◽  
Elastic Limit ◽  
High Pressures ◽  
Narrow Range ◽  
Critical Shear Stress ◽  
Elastohydrodynamic Lubrication ◽  
Elastic Behaviour ◽  
Elastic Solids ◽  
Mineral Oils

Film thickness and traction have been measured in a two-disk machine over a range of rolling and sliding speeds, by using two mineral oils which have previously been studied at lower pressures. The results show: (1) That the lubricant film thickness is correctly given by ‘classical’ elastohydrodynamic theory, even when the behaviour of the lubricant in the high pressure regions is quite different from the Newtonian viscous behaviour postulated in the theory. (2) That over the range of pressure 0.7-2.5GPa both oils behave as elastic solids with a well defined shear modulus. (3) That the elastic compliance of the disks may be comparable with or exceed that in the oil film and must be taken into account in the calculation of the shear modulus of the oils. (4) That at these high pressures the elastic properties, not the viscous properties, of the oil determine the traction when the shear is small. (5) That there is an elastic limit at a critical shear stress above which the shear increases more rapidly than the stress. The magnitude of this critical stress increases with the pressure. (6) That the transition from viscous to elastic behaviour takes place over a relatively narrow range of pressure above which the elastic behaviour becomes insensitive to the rolling speed at which the tests are performed.

scholarly journals Global Challenges and New Approaches in the Common Agricultural Policy 2014 - 2020

2015 ◽  
Vol 3 (2) ◽  
pp. 48-54
Author(s):  
Gabriella Bánhegyi
Keyword(s):  
Climate Change ◽  
Environmental Conditions ◽  
Agricultural Policy ◽  
Common Agricultural Policy ◽  
Environmental Issues ◽  
Biodiversity Loss ◽  
General Strategy ◽  
Agricultural Policies ◽  
Global Challenges ◽  
The Common

Abstract Unfavorable environmental issues raise attention globally toward the concept of sustainability. Agriculture is not only a sector influenced greatly by environmental conditions, but at the same time, as the most important utilizer of land, a major shaper of the environmental conditions. When forming agricultural policies special attention should be paid to issues such as climate change, scarcity of fresh water, food shortage and biodiversity loss — just to name some of them. The new European general strategy for the upcoming 7 years period has brought new measures for the agricultural policy as well, environment and sustainability being among the top issues.

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.

Sign in / Sign up

Export Citation Format

Share Document