POWER ENGINEERING 2A2 CORE MAIN
EXAMINATION QUESTIONS AND ANSWERS SURE A+
✔✔What are 4 methods of Destructive Testing? - ✔✔- Tensile test (tests tensile
strength)
- Hardness Tests
- Impact tests
- Proof tests
✔✔Important factors to consider when conducting a Tensile Test? - ✔✔True. To ensure
valid results, consideration is given to the specimens shape and dimensions, plus the
choice of grips and faces.
✔✔How do you determine what the shape of the specimen should be for a Tensile
Strength test? - ✔✔- Whether the test is using the ASTM E8 or ASTM D638 procedure
✔✔When conducting a tensile strength test, it is important the break occurs where? -
✔✔Within the gauge length.
✔✔Stress is Inversely Proportional to the cross sectional area of an object under load.
True or False? - ✔✔True. Stress becomes greater as cross sectional area decreases.
,✔✔Stress = Load/cross-sectional area. True or False? - ✔✔True
✔✔Stress is calculated from the load inflicted on the specimen and strain and is a
measure of the elongation. True or False? - ✔✔True
✔✔What are the 5 common stress points in a Tensile Strength test? - ✔✔- Proportional
Limit
- Yield stress
- Proof stress
- Ultimate tensile strength
- Final instability point
✔✔Define the Proportional Limit in regards to a tensile strength test. - ✔✔- The stress
point which slip (glide) due to dislocation movement occurs
- Graph is linear up to this point
- Above this point is where elastic to plastic transformation occurs
✔✔Define the Yield Stress in regards to a tensile strength test. - ✔✔- The stress at
which yielding occurs across the whole specimen
- Deformation is purely plastic and non-reversible
✔✔Define the Proof Stress point in regards to a tensile strength test. - ✔✔- Sometimes
referred to as the Yield stress of the material because it is more definitive. Points A and
B aren't always obvious
- This is the point where the specimen has undergone a certain value of strain of 0.2%
(0.2% proof stress)
✔✔Define the Ultimate Tensile Strength in regards to a tensile strength test. - ✔✔- The
point where plastic deformation becomes unstable and a narrow region forms in the
specimen
- This is the peak maximum value of nominal stress during the test (X-axis)
✔✔Define the Final Instability Point in regards to a tensile strength test. - ✔✔This is the
failure point at which fracture occurs
✔✔2 main types of Strain? - ✔✔- Elastic Strain
- Plastic Strain
✔✔Define Elastic Strain. - ✔✔- The stretching of a material within its elastic limit; the
limit of where it will return to its original dimensions when the stress is removed
✔✔Which law of physics defines strain and what does it state? - ✔✔- Hooke's Law can
be used to define strain and states the stress in a solid is directly proportional to the
resulting strain
, ✔✔Stress = E (mod. of elasticity) X Strain. True or False? - ✔✔True
✔✔Plastic strain refers to irreversible defloration of a material - which it has exceeded
its elastic limit. There is no mathematical equation to relate the stress to plastic strain.
True or False? - ✔✔True
✔✔2 ways Strain can be expressed? - ✔✔- Engineering strain
- Relative strain
✔✔Define Engineering Strain. - ✔✔- The ratio of change in length : the original length of
the specimen
✔✔Define True Strain. - ✔✔- The instantaneous change in length compared to the
original length
✔✔Ultimate Tensile Strength measurement will fluctuate with temperature for different
materials. True or False? - ✔✔True
✔✔Define Ultimate Tensile Strength: - ✔✔- The maximum load a specimen sustains
during a test
- The UTS may or may not equate to the strength at fracture
- Brittleness and ductility will affect this measurement, as well as temperature
✔✔What is Hardness? - ✔✔- A measure of the resistance of a material to surface
indentation
✔✔2 ways to measure indentation in regards to Hardness Testing? - ✔✔1) Use a
specific force and measure the penetration depth of indentation OR area of indentation
2) Measure the load that is applied to the inventor mechanism
✔✔What is the most important factor when using the indentation by load technique for
Hardness Testing? - ✔✔- The ability to provide indentations that are geometrically
similar and well defined.
✔✔4 most common hardness testing techniques? - ✔✔- Brinell
- Rockwell
- Vickers
- Knoop
✔✔Name a few methods of applying the force during a Rockwell Hardness test. - ✔✔-
Dead weight
- Pneumatic
- Spring
- Hydraulic
EXAMINATION QUESTIONS AND ANSWERS SURE A+
✔✔What are 4 methods of Destructive Testing? - ✔✔- Tensile test (tests tensile
strength)
- Hardness Tests
- Impact tests
- Proof tests
✔✔Important factors to consider when conducting a Tensile Test? - ✔✔True. To ensure
valid results, consideration is given to the specimens shape and dimensions, plus the
choice of grips and faces.
✔✔How do you determine what the shape of the specimen should be for a Tensile
Strength test? - ✔✔- Whether the test is using the ASTM E8 or ASTM D638 procedure
✔✔When conducting a tensile strength test, it is important the break occurs where? -
✔✔Within the gauge length.
✔✔Stress is Inversely Proportional to the cross sectional area of an object under load.
True or False? - ✔✔True. Stress becomes greater as cross sectional area decreases.
,✔✔Stress = Load/cross-sectional area. True or False? - ✔✔True
✔✔Stress is calculated from the load inflicted on the specimen and strain and is a
measure of the elongation. True or False? - ✔✔True
✔✔What are the 5 common stress points in a Tensile Strength test? - ✔✔- Proportional
Limit
- Yield stress
- Proof stress
- Ultimate tensile strength
- Final instability point
✔✔Define the Proportional Limit in regards to a tensile strength test. - ✔✔- The stress
point which slip (glide) due to dislocation movement occurs
- Graph is linear up to this point
- Above this point is where elastic to plastic transformation occurs
✔✔Define the Yield Stress in regards to a tensile strength test. - ✔✔- The stress at
which yielding occurs across the whole specimen
- Deformation is purely plastic and non-reversible
✔✔Define the Proof Stress point in regards to a tensile strength test. - ✔✔- Sometimes
referred to as the Yield stress of the material because it is more definitive. Points A and
B aren't always obvious
- This is the point where the specimen has undergone a certain value of strain of 0.2%
(0.2% proof stress)
✔✔Define the Ultimate Tensile Strength in regards to a tensile strength test. - ✔✔- The
point where plastic deformation becomes unstable and a narrow region forms in the
specimen
- This is the peak maximum value of nominal stress during the test (X-axis)
✔✔Define the Final Instability Point in regards to a tensile strength test. - ✔✔This is the
failure point at which fracture occurs
✔✔2 main types of Strain? - ✔✔- Elastic Strain
- Plastic Strain
✔✔Define Elastic Strain. - ✔✔- The stretching of a material within its elastic limit; the
limit of where it will return to its original dimensions when the stress is removed
✔✔Which law of physics defines strain and what does it state? - ✔✔- Hooke's Law can
be used to define strain and states the stress in a solid is directly proportional to the
resulting strain
, ✔✔Stress = E (mod. of elasticity) X Strain. True or False? - ✔✔True
✔✔Plastic strain refers to irreversible defloration of a material - which it has exceeded
its elastic limit. There is no mathematical equation to relate the stress to plastic strain.
True or False? - ✔✔True
✔✔2 ways Strain can be expressed? - ✔✔- Engineering strain
- Relative strain
✔✔Define Engineering Strain. - ✔✔- The ratio of change in length : the original length of
the specimen
✔✔Define True Strain. - ✔✔- The instantaneous change in length compared to the
original length
✔✔Ultimate Tensile Strength measurement will fluctuate with temperature for different
materials. True or False? - ✔✔True
✔✔Define Ultimate Tensile Strength: - ✔✔- The maximum load a specimen sustains
during a test
- The UTS may or may not equate to the strength at fracture
- Brittleness and ductility will affect this measurement, as well as temperature
✔✔What is Hardness? - ✔✔- A measure of the resistance of a material to surface
indentation
✔✔2 ways to measure indentation in regards to Hardness Testing? - ✔✔1) Use a
specific force and measure the penetration depth of indentation OR area of indentation
2) Measure the load that is applied to the inventor mechanism
✔✔What is the most important factor when using the indentation by load technique for
Hardness Testing? - ✔✔- The ability to provide indentations that are geometrically
similar and well defined.
✔✔4 most common hardness testing techniques? - ✔✔- Brinell
- Rockwell
- Vickers
- Knoop
✔✔Name a few methods of applying the force during a Rockwell Hardness test. - ✔✔-
Dead weight
- Pneumatic
- Spring
- Hydraulic
