The fatigue life of a part can be improved by
Electroplating
Polishing
Coating
Shot peening
Correct Answer :
D. Shot peening
Related Questions
For a shoe brake, the equivalent coefficient of friction is equal to (where μ = Actual coefficient of friction, and θ = Semi-block angle)
2μ sinθ/(θ + sinθ)
μ sinθ/(2θ + sin 2θ)
4μ sinθ/(θ + sinθ)
4μ sinθ/(2θ + sin 2θ)
The design of pin of a rocker arm of an I.C. engine is based on
Bearing failure
Shearing failure
Bending failure
All of these
The expression 0.175 - 0.841/T is the Lewis form factor for
14 ½° composite and full depth involute system
20° full depth involute system
20° stub system
None of the above
A fast and loose pulley drive is used when
Shafts are arranged parallel and rotate in the opposite directions
Shafts are arranged parallel and rotate in the same directions
Shafts are arranged at right angles and rotate in one definite direction
Driven shaft is to be started or stopped whenever desired without interfering with the driving shaft
Two shafts A and B are made of the same material. The diameter of shaft A is twice as that of shaft B. The power transmitted by the shaft A will be __________ of shaft B.
Twice
Four times
Eight times
Sixteen times
Surface endurance limit of gear material is dependent upon its
Elastic strength
Yield strength
Brinell hardness number
Toughness
A shaft is subjected to a maximum bending stress of 80 N/mm² and maximum shearing stress equal to 30 N/mm² at a particular section. If the yield point in tension of the material is 280 N/mm² and the maximum shear stress theory of failure is used, then the factor of safety obtained will be
2.5
2.8
3.0
3.5
The cam follower extensively used in aircraft engines is
Knife edge follower
Flat faced follower
Spherical faced follower
Roller follower
A key capable of tilting in a recess milled out in a shaft is known as
Woodruff key
Feather key
Flat saddle key
Hollow saddle key
Shear stress theory is applicable for
Ductile materials
Brittle materials
Elastic materials
All of the above
If two springs are in parallel then their overall stiffness will be
Half
Same
Double
None of the above
When a belt drive is transmitting maximum power,
Effective tension is equal to centrifugal tension
Effective tension is half of centrifugal tension
Driving tension on slack side is equal to centrifugal tension
Driving tension on tight side is twice the centrifugal tension
The relation between the pitch of the chain (p) and pitch circle diameter of the sprocket (D) is given by (where T = Number of teeth on the sprocket)
p = D sin (90°/T)
p = D sin (120°/T)
p = D sin (180°/T)
p = D sin (360°/T)
In standard taper roller bearings, the angle of taper of outer raceway is
5°
8°
15°
25°
Two rigid plates are clamped by means of bolt and nut with an initial force F. After tightening, a separating force P (P < F) is applied to the lower plate, which in turn acts on the nut. The tension in the both after this is
F + P
F P
P
F
For high speed engines, the cam follower should move with
Uniform velocity
Simple harmonic motion
Uniform acceleration and retardation
Cycloidal motion
The endurance limit of a material with finished surface in comparison to rough surface is
More
Less
Same
More or less depending on quantum of load
Three different weights fall from a certain height under vacuum. They will take
Same time to reach earth
Times proportional to weight to reach earth
Times inversely proportional to weight to reach earth
None of the above
An alien bolt is
Self locking bolt
Same as stud
Provided with hexagonal depression in head
Used in high speed components
When a material is subjected to fatigue loading, the ratio of the endurance limit to the ultimate tensile strength is
0.20
0.35
0.50
0.65
In the levers of third type, the mechanical advantage is __________ one.
Less than
Equal to
More than
None of these
If shearing stress in nut is half the tensile stress in a bolt, then nut length should be equal to
Diameter of bolt
0.75 × diameter of bolt
1.25 × diameter of bolt
1.5 × diameter of bolt
In a butt welded joint, the size of weld is __________ the throat of weld.
0.5 times
Equal to
2 times
Double
The standard length of the shaft is
6 m
5 m
7 m
All of these
In radial cams, the follower moves
In a direction parallel to the cam axis
In a direction perpendicular to the cam axis
In any direction irrespective of cam axis
Along the cam axis
The shear stress in a beam varies from zero at the outer fibres to a maximum at the________.
Neutral surface
Upper surface
Lower surface
None of these
The toughness of a material _________ when it is heated
Does not change
Increases
Decreases
None of the Above
Allen bolts are
Self locking bolts
Designed for shock load
Used in aircraft application
Provided with hexagonal depression in head
Rankine's theory is used for
Brittle materials
Ductile materials
Elastic materials
Plastic materials
Which of the following key is preferred for the condition when a large amount of impact type torque is to be transmitted in both direction of rotation?
Woodruff key
Feather key
Gib-head key
Tangent key