Exam 2 – Tribology UPDATED ACTUAL
Exam Questions and CORRECT Answers
Types of materials in Tribo-contact wear - CORRECT ANSWER - Metal/Metal-alloys,
Ceramics, and Polymers
Metal key characteristics - CORRECT ANSWER - Ductile and conduct electircity and
heat but vulnerable to corrosion
Ceramics key characteristics - CORRECT ANSWER - Crystalline compounds made of
metal and non-metal elements. High hardness, abrasion resistance, brittleness, and chemical
inhertness
Ceramics - CORRECT ANSWER - Which of the three primary materials are the hardest?
Plastic, Metal, and Ceramic - CORRECT ANSWER - What materials are selected for
artificial hips?
Plastic - CORRECT ANSWER - What material is used for the socket of the hip
replacement?
Metals and Ceramics - CORRECT ANSWER - What materials are often used for the head
and cup of the hip replacement?
1. MoP (metal on plastic)
2. CoP (ceramic on plastic)
3. MoM (metal on metal)
4. CoC (ceramic on ceramic) - CORRECT ANSWER - Most common material
combinations
, CoC - CORRECT ANSWER - Which material combination has the lowest wear and
lowest friction in hip replacements?
CoC - CORRECT ANSWER - Which material combination had the most squeaking occur
due to stick-slip friction in hip replacements?
Factors that affect material selection - CORRECT ANSWER - Geometry, contact forces,
friction
MoM - CORRECT ANSWER - Which material combination has the highest friction in hip
joints?
MoP - CORRECT ANSWER - Which material combination has the highest wear rate in
hip replacements?
Elastic modulus - CORRECT ANSWER - ratio of the stress to the strain of a material
within its elastic behavior (the stiffness of a material)
Poisson's ratio - CORRECT ANSWER - Ratio of transverse to longitudinal strain of a
material in tension.
Yield strength (tensile) - CORRECT ANSWER - What material property is difficult to
measure for ceramics/very-brittle materials?
Hardness - CORRECT ANSWER - Material's resistance to local plastic deformation
Rockwell (HRA/HRB/HRC), Brinell (HB), Vickers (HV) - CORRECT ANSWER - Three
commonly used standard tests for measuring hardness.
3*Yield = H - CORRECT ANSWER - How to approximate hardness if not avaiable.
Exam Questions and CORRECT Answers
Types of materials in Tribo-contact wear - CORRECT ANSWER - Metal/Metal-alloys,
Ceramics, and Polymers
Metal key characteristics - CORRECT ANSWER - Ductile and conduct electircity and
heat but vulnerable to corrosion
Ceramics key characteristics - CORRECT ANSWER - Crystalline compounds made of
metal and non-metal elements. High hardness, abrasion resistance, brittleness, and chemical
inhertness
Ceramics - CORRECT ANSWER - Which of the three primary materials are the hardest?
Plastic, Metal, and Ceramic - CORRECT ANSWER - What materials are selected for
artificial hips?
Plastic - CORRECT ANSWER - What material is used for the socket of the hip
replacement?
Metals and Ceramics - CORRECT ANSWER - What materials are often used for the head
and cup of the hip replacement?
1. MoP (metal on plastic)
2. CoP (ceramic on plastic)
3. MoM (metal on metal)
4. CoC (ceramic on ceramic) - CORRECT ANSWER - Most common material
combinations
, CoC - CORRECT ANSWER - Which material combination has the lowest wear and
lowest friction in hip replacements?
CoC - CORRECT ANSWER - Which material combination had the most squeaking occur
due to stick-slip friction in hip replacements?
Factors that affect material selection - CORRECT ANSWER - Geometry, contact forces,
friction
MoM - CORRECT ANSWER - Which material combination has the highest friction in hip
joints?
MoP - CORRECT ANSWER - Which material combination has the highest wear rate in
hip replacements?
Elastic modulus - CORRECT ANSWER - ratio of the stress to the strain of a material
within its elastic behavior (the stiffness of a material)
Poisson's ratio - CORRECT ANSWER - Ratio of transverse to longitudinal strain of a
material in tension.
Yield strength (tensile) - CORRECT ANSWER - What material property is difficult to
measure for ceramics/very-brittle materials?
Hardness - CORRECT ANSWER - Material's resistance to local plastic deformation
Rockwell (HRA/HRB/HRC), Brinell (HB), Vickers (HV) - CORRECT ANSWER - Three
commonly used standard tests for measuring hardness.
3*Yield = H - CORRECT ANSWER - How to approximate hardness if not avaiable.
