Carlos Sarria
MANE 6960
Homework 01
1) Use a web browser and the key word “Tribology” to do some research on the web
AND also in the RPI Library collection leading you to a fuller understanding and
significance of the term. Then write a 250 word long essay explaining what does the
term mean and which scientific and engineering disciplines are involved in the study
of tribology and why. Also write about a selected technical problem of your choice
that may require a tribological approach and explain why you think this may be so.
Append to your write-up a selected list of the references and sources that you found
most useful and interesting when doing your research.
Tribology is the science that focuses on studying the interaction between surfaces of objects
contacting and rubbing with each other. The word comes from the Greek word “tribos” meaning
“rubbing” and the suffix “ology” meaning the “study of” (Shaffer). This science involves the
study of key fields including chemistry, fluid mechanics, materials and solid mechanics (Szeri).
Shaffer explains that it is important to know the materials surface roughness which is responsible
for the contact area and the resulting contact stresses in addition to the lubricant paths and
reservoirs associated with it. This can only be known from a thorough study of material science.
Similarly, by studying the chemistry aspects related to the materials, one can determine if there
will be any chemical compatibility issues, or what lubricant properties are the most desirable for
the application.
The science of tribology is divided into three branches: Friction, wear and lubrication (Szeri).
Friction can be defined as a phenomenon occurring opposite to the direction of motion when
there is relative motion between the contacting surfaces (Szeri). Wear is the progressive loss of
material due to the rubbing of two or more surfaces (Szeri). The purpose of using a lubricant is to
reduce friction, resulting in a reduced wear, while transporting debris away from interface and
providing cooling (Shaffer).
Tribology involves so many aspects of our daily lives that it is easy to identify challenging
applications where the study of this science is required. One current application is designing
very low rolling resistance tires that help cars achieve much lower fuel consumption. Tire
manufacturers have carried out research and developed their own low resistance tires. Efficient
tires are so important that a 10% reduction of rolling resistance can result in up to 2%
improvement in fuel consumption (Auto Global News). Thus, one can see how understanding
both the friction and wear mechanisms on car tires can lead to game changing technology.
Similarly, tribology can help engineers develop efficient tires with better traction on the snow so
that drivers don’t have to change tires during winters, and avoid this additional expense.
Works Cited
1)
2)
3)
Shaffer, Steven J. "Tribology 101: Introduction to the Basics of Tribology."Bruker. N.p.,
29 Jan. 2013. Web. 21 Feb. 2015.
Szeri, Andras Z. “Tribology.” AccessScience. McGraw-Hill Education, 2014. Web. 21
Feb. 2015
"US: Ford Increases Availability of Fuel-Efficient Tires Across Lineup and Leads
Research Efforts for Better Technology." just - auto global newsJul 06
2011. ProQuest. Web. 21 Feb. 2015 .
2) Read carefully through the presentation slides presented by Dr. Chris Taylor during the 2004
George Stephenson Lecture to the Institution of Mechanical Engineers in England, select a particular
point that catches your interest, do some further research and prepare a 250-word long essay about
it.
In his slides, Dr. Taylor talks briefly about the different regimes of lubrication that exists. Due to
the importance role that this aspect of tribology plays on the durability of materials, it’s important to
expand on it. Rizvi explains that there are different parameters that define the lubrication environment
including friction, lubricant viscosity, and the equipment speed and load (Rizvi 4). Rizvi elaborates that
there is a relationship between the lubricant’s viscosity, equipment’s speed and load, and the thickness
of the thickness of the lubricant’s film. Using these relationships, four lubrication regimes can be
defined: Fluid-film, boundary, mixed-film, and hydrostatic (Rizvi 5).
Fluid-film lubrication is the most desirable the moving surfaces are separated by a lubricant film
(Rizvi 5). This type of lubrication is only effective when the low in the contact zone is low. The author
also mentions that most lubricated parts of today’s internal combustion engines utilize this type of
lubrication.
Boundary lubrication occurs under high loads and very low speeds which leads to the lack of
effective lubrication (Rizvi 5). When such condition arise, the maximum metal-to-metal contact occurs,
and if this is not controlled this dry friction can lead to the hardware’s failure (Rizvi 5). To mitigate this,
engineers and mechanics use anti-wear chemicals and extreme pressure agents.
Mixed-film lubrication, as its name suggests, resides in between the fluid-film and the boundary
lubrication regimes, and possesses characteristics of both. Thus, there are regions of no metal-to-metal
contact, and others where the opposite occurs (Rizvi 5).
Hydrostatic lubrication is characterized by the lack of wear, low friction, and high load capacity
among others (Rizvi 5). This type of lubrication does not depend on the motion of the surfaces.
Therefore the surfaces are allowed to completely separate by the static film of the lubricant.
Works Cited
1) Rizvi, Syed Q. A.. (2009). Comprehensive Review of Lubricant Chemistry, Technology, Selection,
and Design - 1.2.2.1 Lubrication Regimes. ASTM International
3) List at least three ideas that you believe could be good research topics for the project that you will
have to work on in this course.
Potential topics for class projects include:
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Wear resistance of artificial denture teed
Friction and wear of automobile breaks
Wear resistant surfaces
Friction and wear performance of thermally-stable vegetable-based lubricants