Tribology Exam UPDATED ACTUAL Exam
Questions and CORRECT Answers
Where does energy go during friction? - CORRECT ANSWER - - Deformation
(elastic/plastic)
- Sparks/light/photons
- Sound
- Temperature
- Chemical reactions (oxidation,corrosion)
What are the tribological factors? - CORRECT ANSWER - - Materials
- Surfaces
- Lubricant
- Operating conditions
What are the tribological factors of materials? - CORRECT ANSWER - - Mechanical
properties
- Friction
-Wear resistance
- Compatibility
What are the tribological factors of surfaces? - CORRECT ANSWER - - Comformity
- Surface texture
What are the tribological factors of lubricant? - CORRECT ANSWER - - Viscosity
- Additives
- Contamination
- Degradation
,What are the tribological factors of operating conditions? - CORRECT ANSWER - - Load
- Relative motion
- Temperature
- Environment
What parameters are used to describe rough surfaces? - CORRECT ANSWER --
Irregularities
- Surface texture
- Waviness
- Roughness
- Lay
What are the three qualitative ways to assess surface texture? - CORRECT ANSWER --
Optical microscopy
- Scanning electron microscopy
- Transmission electron microscopy
What are the three quantitative ways to assess surface texture? - CORRECT ANSWER --
Stylus profilometry
- Atomic force microscopy
- Non-contacting profilometry
What 3 manufacturing processes give the smoothest finish and what Ra range can they achieve?
- CORRECT ANSWER - Honing, Polishing, Lapping (0.8 to 0.01 um)
What are the assumptions in Hertzian contact theory? - CORRECT ANSWER - - One
body is perfectly elastic and the other is perfectly rigid
- Bodies are homogenous and isotropic
, - No friction and adhesion
- Bodies are perfectly smooth
What is the plasticity index and how does it indicate elastic or plastic behviour? - CORRECT
ANSWER - Ψ << 1 asperity deformation is purely elastic
Ψ >> 1 asperity deformation is plastic
What is shakedown? - CORRECT ANSWER - - Stabilization of Lubricant Film
- Surface Adaptation
- Reduced Surface Distress
By what other names is the Lambda ratio known, what is the formula and what does lambda
mean? - CORRECT ANSWER - - Specific film thickness
- Film thickness ratio
- Lambda ratio (λ)
Based on the value of λ
λ > 10 then there is no possibility of surface contact
λ < 1 then a high degree of contact will occur between the surfaces
What is the formula for the coefficient of friction? - CORRECT ANSWER - 𝜇 = 𝐹/𝑊
What are the Three Laws of Dry Friction? - CORRECT ANSWER - 1. The Friction Force
(F) is directly proportional to the Applied Load (W)
2. The Friction Force (F) is independent of Apparent Area of Contact (A)
3. The Friction Force (F) is independent of the Sliding Velocity (V)
What are the four simple theories of dry friction? - CORRECT ANSWER - 1. Geometrical
2. Adhesion
3. Ploughing
Questions and CORRECT Answers
Where does energy go during friction? - CORRECT ANSWER - - Deformation
(elastic/plastic)
- Sparks/light/photons
- Sound
- Temperature
- Chemical reactions (oxidation,corrosion)
What are the tribological factors? - CORRECT ANSWER - - Materials
- Surfaces
- Lubricant
- Operating conditions
What are the tribological factors of materials? - CORRECT ANSWER - - Mechanical
properties
- Friction
-Wear resistance
- Compatibility
What are the tribological factors of surfaces? - CORRECT ANSWER - - Comformity
- Surface texture
What are the tribological factors of lubricant? - CORRECT ANSWER - - Viscosity
- Additives
- Contamination
- Degradation
,What are the tribological factors of operating conditions? - CORRECT ANSWER - - Load
- Relative motion
- Temperature
- Environment
What parameters are used to describe rough surfaces? - CORRECT ANSWER --
Irregularities
- Surface texture
- Waviness
- Roughness
- Lay
What are the three qualitative ways to assess surface texture? - CORRECT ANSWER --
Optical microscopy
- Scanning electron microscopy
- Transmission electron microscopy
What are the three quantitative ways to assess surface texture? - CORRECT ANSWER --
Stylus profilometry
- Atomic force microscopy
- Non-contacting profilometry
What 3 manufacturing processes give the smoothest finish and what Ra range can they achieve?
- CORRECT ANSWER - Honing, Polishing, Lapping (0.8 to 0.01 um)
What are the assumptions in Hertzian contact theory? - CORRECT ANSWER - - One
body is perfectly elastic and the other is perfectly rigid
- Bodies are homogenous and isotropic
, - No friction and adhesion
- Bodies are perfectly smooth
What is the plasticity index and how does it indicate elastic or plastic behviour? - CORRECT
ANSWER - Ψ << 1 asperity deformation is purely elastic
Ψ >> 1 asperity deformation is plastic
What is shakedown? - CORRECT ANSWER - - Stabilization of Lubricant Film
- Surface Adaptation
- Reduced Surface Distress
By what other names is the Lambda ratio known, what is the formula and what does lambda
mean? - CORRECT ANSWER - - Specific film thickness
- Film thickness ratio
- Lambda ratio (λ)
Based on the value of λ
λ > 10 then there is no possibility of surface contact
λ < 1 then a high degree of contact will occur between the surfaces
What is the formula for the coefficient of friction? - CORRECT ANSWER - 𝜇 = 𝐹/𝑊
What are the Three Laws of Dry Friction? - CORRECT ANSWER - 1. The Friction Force
(F) is directly proportional to the Applied Load (W)
2. The Friction Force (F) is independent of Apparent Area of Contact (A)
3. The Friction Force (F) is independent of the Sliding Velocity (V)
What are the four simple theories of dry friction? - CORRECT ANSWER - 1. Geometrical
2. Adhesion
3. Ploughing
