LESSON 1 Flashcards
-Tribology comes from the Greek
word
“tribos”
what does tribos means?
rubbing
Tribology
It focuses on friction, wear
and lubrication of interacting
surfaces.
5,000 BC
early humans learned that by rubbing sticks they can produced fire
3500
rolling motion required less effort than sliding , wheel was invented
what year did Leonardo da Vinci
formulated 2 basic laws of friction?
1495
What are the 2 laws of friction that Leonard made?
- Friction is independent of contact area.
- Friction is proportional to load.
Who said that the cause of deformation and wear of surfaces is friction?
Guillaume Amontons
What year did Guillame Amontons rediscovered the two basic laws?
1699
Who said that moving friction was not dependent on speed or velocity?
Sir isaac Newton
Who formulated the third law of friction?
Sir Isaac Newton
What year did Phillip Bowen and David Tabor gave physical explanation for the observed laws of friction?
1950
Who determined that the true area of contact, is avery small percentage of the apparent area?
Phillip Bowden and David Tabor
As the normal force increases
more asperities came into contact and the average area of each asperity contact grows
Who said the following? Amontons Law of Friction are the first quantitative description of tribological process. Attemps to explain these laws have been central to the development of tribology.
Bill Needelman
In what year did the elucidation of hydrodynamic lubraication began in England?
1883
Who did the elucidation of hydrodynamic lubrication in England?
Beauchamp Tower
Who published a differential equation describing this pressure buildup of the oil in the narrowing conveging gap between journal bearing surfaces?
Osborne Reynolds
In what year did Osborne Reynolds published a differential equation?
1886
Who published the Stribeck curve?
Richard Stribeck
What is a plot of frictionas it related to viscoscity, speed and load?
Stribeck curve
When was the Stribeck cruve published?
1902
What year did Arnold Sommerfeld refined the work into a formal theory of hydrodynami lubrication?
1905
Who refined the work of Tower and Reynolds?
Arnold Sommerfeld
It is the force that hinders or resist the relative motion of two contacting bodies.
friction
What is the
friction present between
two or more objects that
are not moving with
respect to each other.
Static Friction
What is the
friction present between
two or more objects that are
in motion with respect to
each other.
Kinetic Friction
The magnitude of _____ is greater due to
the greater value of its
coefficient.
static friction
The magnitude of the ______ is comparatively
lesser due to the low value of
its coefficient.
kinetic
friction
The equation representing static friction is given by
Fs= μs N
The equation representing
kinetic friction is given by
Fk = μk N
takes place when an object rolls on the surface.
Rolling friction
takes place when two surfaces are rubbed against each other.
Sliding Friction
takes place due to the deformation of surfaces.
Rolling Friction
takes place
due to interlocking between
microscopic surfaces.
Sliding friction
is dependent on the radius of the rolling object, the depth to which the object can sink, and the toughness of the surface.
coefficient of rolling friction
depends on the texture of the surface and temperature to a certain extent. It is independent of external factors.
coefficient of sliding friction
Coefficient of sliding friction:
Fsl = μslN
Coefficient of rolling friction
Fr = μrN
-is a process removal of material from one or both two solid surfaces in solid state contact, occurring when these two solid surfaces are in sliding
or rolling motion together.
Wear
-it is the progressive damage, involving material loss, which occurs on the surface of a component as a result of its motion relative to the adjacent
working parts.
Wear
-occurs when a harder material is rubbing against a softer material.
Abrasive Wear
-the impingement of solid particles, or small drops of liquid or gas on a solid surface cause wear what is known as erosion of materials and components.
Erosive Wear
-two bodies sliding over or pressed into each other which promote the
material transfer from one to another.
Frictional Wear/ Adhesive Wear
This gem cannot be polished without friction norman without trials
Confucius
