POWER ENGINEERING 2A2 TEST PAPER 2026
FULL SOLUTION VERIFIED
◉ What are the four methods of destructive testing? Answer: Tensile
Tests
Hardness Tests
Impact Tests
Proof Tests
◉ In a tensile test, how is the shape of the specimen determined?
Answer: The shape is defined by the standards established by ASTM
◉ In a tensile test, why is the shape of the specimen important?
Answer: So that the beak occurs in the "gauge length" section.
◉ What is the mechanism called that is used for performing tensile
tests? Answer: An extensometer
◉ When performing tensile tests, what are the five stress points
plotted? Answer: Proportional Limit
Yield stress
Proof Stress
,Ultimate tensile Strength
Final instability point
◉ What is the proportional limit as it pertains to tensile tests?
Answer: The stress point at which slip (or glide) due to dislocation
movement occurs.
◉ What is yield stress as it pertains to tensile tests? Answer: The
stress at which yielding occurs across the whole specimen.
At this point, deformation is purely plastic (non-reversible)
◉ What is proof stress as it pertains to tensile tests? Answer: The
point at which a specimen has undergone a certain value of
permanent strain. Usually 0.2%
◉ What is the ultimate tensile strength (UTS) as it pertains to tensile
tests? Answer: It is the point at which plastic deformation becomes
unstable and a narrow region (a neck) forms in the specimen.
◉ What is the final instability point as it pertains to tensile tests?
Answer: It is the failure point, at which fracture occurs.
◉ What are the two main types of strain? Answer: Elastic strain
,Plastic strain
◉ Explain elastic strain Answer: Elastic strain is the stretching of
material within its elastic limit. It will return to its original
dimensions when the stress is removed.
◉ Explain plastic strain Answer: Plastic strain happens once the
material has exceeded its elastic limit. It is the irreversible
deformation of a material.
◉ What is engineering strain? Answer: This is the one outlined in
the academic supplement.
Strain=ΔL/Original L
◉ What is true strain? Answer: It is similar to engineering strain but
based on the instantaneous length of the specimen as the test
progresses.
Instantaneous length
True Strain = ln --------------------------
Original length
, ◉ What is the hardness measurement? Answer: The resistance of a
material to surface indentation.
◉ What are the four common hardness testing methods? Answer:
Brinell
Rockwell
Vickers
Knoop
◉ Describe the Brinell Hardness Test. Answer: Specimen placed on
an anvil
Load applied through a plunger and ball
Held for 10 to 30 seconds
Diameter measured twice offset by 90° to get mean diameter
Hardness number calculated
◉ What is the most widely used hardness test? Why? Answer: The
Rockwell hardness test
Because it's simple to perform
◉ What do Rockwell hardness testers use as an indentor? Answer:
Either a diamond cone or ball
FULL SOLUTION VERIFIED
◉ What are the four methods of destructive testing? Answer: Tensile
Tests
Hardness Tests
Impact Tests
Proof Tests
◉ In a tensile test, how is the shape of the specimen determined?
Answer: The shape is defined by the standards established by ASTM
◉ In a tensile test, why is the shape of the specimen important?
Answer: So that the beak occurs in the "gauge length" section.
◉ What is the mechanism called that is used for performing tensile
tests? Answer: An extensometer
◉ When performing tensile tests, what are the five stress points
plotted? Answer: Proportional Limit
Yield stress
Proof Stress
,Ultimate tensile Strength
Final instability point
◉ What is the proportional limit as it pertains to tensile tests?
Answer: The stress point at which slip (or glide) due to dislocation
movement occurs.
◉ What is yield stress as it pertains to tensile tests? Answer: The
stress at which yielding occurs across the whole specimen.
At this point, deformation is purely plastic (non-reversible)
◉ What is proof stress as it pertains to tensile tests? Answer: The
point at which a specimen has undergone a certain value of
permanent strain. Usually 0.2%
◉ What is the ultimate tensile strength (UTS) as it pertains to tensile
tests? Answer: It is the point at which plastic deformation becomes
unstable and a narrow region (a neck) forms in the specimen.
◉ What is the final instability point as it pertains to tensile tests?
Answer: It is the failure point, at which fracture occurs.
◉ What are the two main types of strain? Answer: Elastic strain
,Plastic strain
◉ Explain elastic strain Answer: Elastic strain is the stretching of
material within its elastic limit. It will return to its original
dimensions when the stress is removed.
◉ Explain plastic strain Answer: Plastic strain happens once the
material has exceeded its elastic limit. It is the irreversible
deformation of a material.
◉ What is engineering strain? Answer: This is the one outlined in
the academic supplement.
Strain=ΔL/Original L
◉ What is true strain? Answer: It is similar to engineering strain but
based on the instantaneous length of the specimen as the test
progresses.
Instantaneous length
True Strain = ln --------------------------
Original length
, ◉ What is the hardness measurement? Answer: The resistance of a
material to surface indentation.
◉ What are the four common hardness testing methods? Answer:
Brinell
Rockwell
Vickers
Knoop
◉ Describe the Brinell Hardness Test. Answer: Specimen placed on
an anvil
Load applied through a plunger and ball
Held for 10 to 30 seconds
Diameter measured twice offset by 90° to get mean diameter
Hardness number calculated
◉ What is the most widely used hardness test? Why? Answer: The
Rockwell hardness test
Because it's simple to perform
◉ What do Rockwell hardness testers use as an indentor? Answer:
Either a diamond cone or ball
