©Themoon EXAM SOLUTIONS
26/11/2024 10:59AM
Machine Design Test 1 Questions and
Answers
Fatigue Loading - Answers✓✓Occurs when a structure experiences dynamic, fluctuating or
variable loads
Fatigue - Answers✓✓an issue in any structure that is subjected to variable loading (mechanical,
pressure, or thermal); often the cause of many structure failures
Fatigue Failure - Answers✓✓occurs due to excessive dynamic, repeated, fluctuating or variable
loading
What is a frequent cause of catastrophic failures? Why? - Answers✓✓Fatigue Loading; it is
poorly understood and difficult predict
Where do fatigue failures occur? - Answers✓✓Typically at stress levels significantly lower that
the yield strengths of the materials. Using static failure theories can lead to unsafe designs
when loads are dynamic
What are the two categories of fatigue? - Answers✓✓Low cycle
High cycle
Fatigue is caused by... - Answers✓✓Bending, torsional, axial, combined, thermal, and pressure
loads
, ©Themoon EXAM SOLUTIONS
26/11/2024 10:59AM
Plastic Strain - Answers✓✓occurs when the stress at the discontinuity exceeds the elastic limit
Material that exhibit a decreasing elastic limit - Answers✓✓Cold Drawn Steel
Material that exhibit an increasing elastic limit - Answers✓✓Annealed Steel
Coffin- Manson Relationship - Answers✓✓the sum of the elastic and plastic strain amplitudes
(total strain amplitude); the relationship between fatigue life and total strain amplitude
What do S-N curves represent? - Answers✓✓average lifetime versus stress level
An unfinished rolled or forged element may _________________ or less of the same part
which has been ground and polished - Answers✓✓have half the fatigue strength
Surface Factor Formula - Answers✓✓Cf=aSut^b
Impact - Answers✓✓a load applied suddenly which creates greater stresses in any application
than an equal load applied gradually
The size factor, Cs, for axial loading - Answers✓✓there is no size effect, therefore Cs = 1
Brittle Fracture - Answers✓✓A strong possibility when operating temperatures are below room
temperatures and should be investigated first under these circumstances
Yield - Answers✓✓should be investigates first when the operating temperature is higher than
room temperature; Yield strength drops off rapidly with increased temperature
26/11/2024 10:59AM
Machine Design Test 1 Questions and
Answers
Fatigue Loading - Answers✓✓Occurs when a structure experiences dynamic, fluctuating or
variable loads
Fatigue - Answers✓✓an issue in any structure that is subjected to variable loading (mechanical,
pressure, or thermal); often the cause of many structure failures
Fatigue Failure - Answers✓✓occurs due to excessive dynamic, repeated, fluctuating or variable
loading
What is a frequent cause of catastrophic failures? Why? - Answers✓✓Fatigue Loading; it is
poorly understood and difficult predict
Where do fatigue failures occur? - Answers✓✓Typically at stress levels significantly lower that
the yield strengths of the materials. Using static failure theories can lead to unsafe designs
when loads are dynamic
What are the two categories of fatigue? - Answers✓✓Low cycle
High cycle
Fatigue is caused by... - Answers✓✓Bending, torsional, axial, combined, thermal, and pressure
loads
, ©Themoon EXAM SOLUTIONS
26/11/2024 10:59AM
Plastic Strain - Answers✓✓occurs when the stress at the discontinuity exceeds the elastic limit
Material that exhibit a decreasing elastic limit - Answers✓✓Cold Drawn Steel
Material that exhibit an increasing elastic limit - Answers✓✓Annealed Steel
Coffin- Manson Relationship - Answers✓✓the sum of the elastic and plastic strain amplitudes
(total strain amplitude); the relationship between fatigue life and total strain amplitude
What do S-N curves represent? - Answers✓✓average lifetime versus stress level
An unfinished rolled or forged element may _________________ or less of the same part
which has been ground and polished - Answers✓✓have half the fatigue strength
Surface Factor Formula - Answers✓✓Cf=aSut^b
Impact - Answers✓✓a load applied suddenly which creates greater stresses in any application
than an equal load applied gradually
The size factor, Cs, for axial loading - Answers✓✓there is no size effect, therefore Cs = 1
Brittle Fracture - Answers✓✓A strong possibility when operating temperatures are below room
temperatures and should be investigated first under these circumstances
Yield - Answers✓✓should be investigates first when the operating temperature is higher than
room temperature; Yield strength drops off rapidly with increased temperature
