Thin-cylinder hoop stress is approximately what?
A pd / 4t
B pd / 2t
C 2pt / d
D p / dt
Answer: B. pd / 2t. For a thin-walled closed cylinder, circumferential stress is pd/(2t).
Thin-cylinder longitudinal stress is approximately what?
A pd / 2t
B 4pt / d
C p / 2dt
D pd / 4t
Answer: D. pd / 4t. For a thin-walled closed cylinder, longitudinal stress is pd/(4t).
Thick-cylinder stress analysis commonly uses which theory?
A Lamé equations
B Lewis equation
C Watt governor theory
D Bernoulli theorem
Answer: A. Lamé equations. Lamé equations describe radial and circumferential stress in thick cylinders.
Euler column load varies inversely with what?
A Column diameter only
B Elastic modulus squared
C Effective length squared
D End load squared
Answer: C. Effective length squared. Euler critical load is proportional to EI/(effective length)^2.
Pinned-pinned column effective length equals what?
A Physical length
B Half physical length
C Twice physical length
D Four times length
Answer: A. Physical length. For ideal pin ends, the effective length factor is one.
A fixed-free column has effective length about what?
A Half its length
B Twice its length
C Same length
D Four times length
Answer: B. Twice its length. A cantilever column has effective length factor two.
Fatigue strength often decreases when surface finish becomes what?
A Smoother
B More reflective
C More uniform
D Rougher
Answer: D. Rougher. Surface roughness creates local stress raisers and can reduce fatigue strength.
Goodman design line uses ultimate strength for what stress?
A Alternating stress intercept
B Mean stress intercept
C Shear modulus
D Thermal stress only
Answer: B. Mean stress intercept. The linear Goodman relation uses ultimate tensile strength at the mean-stress axis.
Soderberg design line uses yield strength for what stress?
A Alternating stress intercept
B Elastic modulus
C Mean stress intercept
D Shear stress only
Answer: C. Mean stress intercept. Soderberg is more conservative and uses yield strength on the mean-stress axis.
Gerber fatigue relation is commonly represented as what?
A Parabolic curve
B Straight vertical line
C Circle through origin
D Constant stress line
Answer: A. Parabolic curve. The Gerber relation models a parabolic interaction between mean and alternating stress.
Miner’s rule estimates cumulative what?
A Elastic modulus
B Bearing preload
C Gear ratio
D Fatigue damage
Answer: D. Fatigue damage. Linear damage accumulation sums fractions of life consumed at each stress level.
Fatigue notch factor Kf depends on Kt and what?
A Notch sensitivity
B Poisson ratio only
C Shaft speed only
D Bearing life
Answer: A. Notch sensitivity. Kf = 1 + q(Kt−1), where q is notch sensitivity.
A rotating shaft’s critical speed is linked to what?
A Gear module
B Key shear strength
C Thread pitch
D Lateral natural frequency
Answer: D. Lateral natural frequency. Critical speed occurs when running speed approaches a lateral natural frequency.
A shaft under combined bending and torsion is checked using what?
A Pressure angle
B Equivalent stress
C Pitch diameter only
D Spring rate
Answer: B. Equivalent stress. Combined loading is commonly reduced to an equivalent stress using a failure criterion.
A design for manufacturability aims to reduce what?
A Material strength
B Production difficulty
C Required function
D Safety margin always
Answer: B. Production difficulty. Design for manufacturability simplifies processes, tolerances and assembly while meeting requirements.
A datum provides what for dimensional inspection?
A Reference surface or axis
B Fatigue limit
C Lubricant path
D Gear ratio
Answer: A. Reference surface or axis. A datum establishes the reference from which geometric dimensions are defined and inspected.
Creep is time-dependent deformation under what?
A Zero load
B One impact only
C Sustained load
D Pure rolling
Answer: C. Sustained load. Creep is gradual deformation under sustained stress, often important at elevated temperature.
Wear is material loss from which interaction?
A Elastic unloading
B Thermal radiation
C Surface contact motion
D Static pressure only
Answer: C. Surface contact motion. Wear results from contacting surfaces sliding, rolling or impacting.
A dynamic load rating helps select which component?
A Rolling bearing
B Power screw only
C Welded joint only
D Compression spring only
Answer: A. Rolling bearing. Bearing dynamic capacity is used with equivalent load to estimate rating life.
An interference fit can be assembled by heating which part?
A Shaft key only
B Bearing cage
C Washer only
D Hub
Answer: D. Hub. Heating the hub expands its bore and can ease assembly over a shaft.
A transition fit is selected when assembly needs what?
A Large running clearance
B Permanent sliding
C Close location accuracy
D No dimensional control
Answer: C. Close location accuracy. Transition fits provide close location with small possible clearance or interference.
A bearing’s static rating is checked against what?
A Fatigue life only
B Gear tooth pitch
C Permanent deformation risk
D Shaft twist only
Answer: C. Permanent deformation risk. Static load capacity limits permanent raceway deformation under stationary or shock loading.
For fatigue sizing, alternating stress is half of what?
A Mean stress
B Stress range
C Ultimate strength
D Modulus of elasticity
Answer: B. Stress range. Stress amplitude equals one-half the difference between maximum and minimum stress.
A cyclic stress with nonzero average has what?
A Mean stress
B Zero stress range
C No fatigue risk
D Pure hydrostatic pressure
Answer: A. Mean stress. A nonzero average over the cycle is the mean stress component.
A bolted joint’s joint stiffness affects what?
A Gear contact ratio
B Spring index
C Shaft polar moment
D Load shared by bolt
Answer: D. Load shared by bolt. Joint stiffness controls how external axial load is divided between the bolt and clamped members.