Machine design converts requirements into what?
A Component geometry
B Lubricant color
C Operating schedule
D Shop location
Answer: A. Component geometry. Machine design selects geometry, material and details that meet function and constraints.
Factor of safety is failure strength divided by what?
A Elastic modulus
B Density
C Working stress
D Fatigue life
Answer: C. Working stress. Factor of safety compares limiting strength with the applied working stress.
A common ductile-material yield criterion is which?
A Bernoulli criterion
B Von Mises criterion
C Euler criterion
D Coulomb friction law
Answer: B. Von Mises criterion. The distortion-energy or von Mises criterion is widely used for ductile yielding.
The stress concentration factor Kt is maximum stress divided by what?
A Nominal stress
B Yield strength
C Mean stress
D Shear modulus
Answer: A. Nominal stress. Kt compares local peak stress with nominal stress away from a geometric discontinuity.
A fatigue failure is caused mainly by what?
A One static load
B Uniform temperature
C Low surface area
D Repeated stress cycles
Answer: D. Repeated stress cycles. Fatigue damage accumulates under repeated or fluctuating stress cycles.
An S-N curve plots stress amplitude against what?
A Cycles to failure
B Strain energy only
C Mean temperature
D Elastic modulus
Answer: A. Cycles to failure. An S-N curve relates cyclic stress level to life in cycles.
An endurance limit represents fatigue strength for what?
A One load cycle
B Very long life
C Zero mean stress only
D Instant failure
Answer: B. Very long life. For some steels, an endurance limit approximates a stress below which very long fatigue life is expected.
The Tresca criterion is based on maximum what?
A Principal strain
B Shear stress
C Hydrostatic pressure
D Elastic energy only
Answer: B. Shear stress. Tresca predicts yielding when maximum shear stress reaches the shear yield limit.
A brittle-material failure check often emphasizes maximum what?
A Shear strain only
B Mean temperature
C Principal stress
D Poisson ratio
Answer: C. Principal stress. Brittle fracture is commonly assessed using principal tensile stress or a brittle-fracture criterion.
Plastic deformation remains after which event?
A Load removal
B Elastic unloading
C Stress calculation
D Thermal equilibrium
Answer: A. Load removal. Plastic strain is permanent and remains after the load is removed.
Young’s modulus is normal stress divided by what?
A Lateral strain
B Shear force
C Volume change
D Elastic strain
Answer: D. Elastic strain. In the linear elastic range, Young’s modulus is stress over longitudinal strain.
Poisson ratio compares lateral strain with what?
A Shear stress
B Thermal strain
C Volumetric stress
D Longitudinal strain
Answer: D. Longitudinal strain. Poisson’s ratio is the negative ratio of lateral strain to longitudinal strain.
A dimensional tolerance specifies what?
A Allowed size variation
B Surface color range
C Material density
D Maximum cycle count
Answer: A. Allowed size variation. Tolerance defines the permitted variation in a dimension.
A clearance fit always has what?
A Negative clearance
B Positive clearance
C Zero tolerance
D Interference only
Answer: B. Positive clearance. In a clearance fit, the smallest hole remains larger than the largest shaft.
An interference fit always has what?
A Positive clearance
B Zero load
C Free rotation
D Negative clearance
Answer: D. Negative clearance. An interference fit has a shaft larger than the mating hole before assembly.
A transition fit can produce what?
A Only large clearance
B Only large interference
C Clearance or interference
D No contact ever
Answer: C. Clearance or interference. Manufacturing tolerances can make a transition fit result in either small clearance or small interference.
Surface roughness mainly describes what?
A Overall part length
B Bulk hardness
C Elastic modulus
D Fine surface irregularities
Answer: D. Fine surface irregularities. Roughness characterizes short-wavelength surface texture.
Reliability is the probability that a part will do what?
A Perform without failure
B Reach yield immediately
C Have zero mass
D Avoid all wear
Answer: A. Perform without failure. Reliability is the probability of satisfactory operation for a stated time and conditions.
Design stress is normally limited below what?
A Zero stress
B Ultimate strain
C Thermal conductivity
D Allowable strength
Answer: D. Allowable strength. Allowable stress includes a margin below the chosen failure strength.
A dynamic load factor accounts for what?
A Load amplification
B Material density
C Manufacturing cost
D Surface color
Answer: A. Load amplification. Dynamic effects can make actual peak loads exceed nominal static loads.
A notch increases local stress mainly by what?
A Lower elastic modulus
B Higher density
C Geometric discontinuity
D Longer shaft length
Answer: C. Geometric discontinuity. Notches and abrupt geometry changes disturb the stress field and raise local stress.
The Goodman fatigue relation uses mean stress and what?
A Gear ratio
B Spring index
C Stress amplitude
D Thermal expansion
Answer: C. Stress amplitude. Goodman design compares alternating stress and mean stress with fatigue and ultimate strengths.
A design margin is available strength minus what?
A Elastic modulus
B Applied demand
C Part mass
D Cycle frequency
Answer: B. Applied demand. Margin measures how much capacity remains beyond the applied demand.
A load factor accounts for expected what?
A Surface waviness
B Service load variation
C Dimensional units
D Material color
Answer: B. Service load variation. Design loads include foreseeable variation and service conditions.
A brittle material typically shows what before fracture?
A Large permanent strain
B Perfect ductility
C Limited plastic deformation
D Unlimited necking
Answer: C. Limited plastic deformation. Brittle materials often fracture with little plastic deformation.