The material generally used for aircraft components is
Mild steel
High speed steel
Stainless steel
Aluminium
Correct Answer :
D. Aluminium
Related Questions
The form factor of a helical gear __________ with the increase in the helix angle.
Increases
Decreases
Remains constant
None of these
In the assembly of pulley, key and shaft
Pulley is made the weakest
Key is made the weakest
Key is made the strongest
All the three are designed for equal strength
The load cup of a screw jack is made separate from the head of the spindle to
Prevent the rotation of load being lifted
Enhance the load carrying capacity of the jack
Reduce the effort needed for lifting the working load
Reduce the value of frictional torque
The included angle in unified of American National threads is
60°
55°
47°
29°
The shearing stresses in the inner face as compared to outer face of the wire in a heavy close coiled spring is
Larger
Smaller
Equal
Larger/smaller depending on diameter of spring coil
The square threads are usually found on
Spindles of bench vices
Railway carriage couplings
Feed mechanism of machine tools
Screw cutting lathes
In a full journal bearing, the angle of contact of the bearing with the journal is
120°
180°
270°
360°
The centre distance between two meshing involute gears is equal to
(Sum of base circle radii)/cosφ
(Difference of base circle radii)/cosφ
(Sum of pitch circle radii)/cosφ
(Difference of pitch circle radii)/cosφ
The resistance to fatigue of a material is measured by
Elastic limit
Ultimate tensile strength
Young's modulus
Endurance limit
The initial tension (in newtons) in a bolt used for making a fluid tight joint like steam engine cover joints, is calculated by the relation (where d = Nominal diameter of bolt in mm)
1420 d
1680 d
2080 d
2840 d
The constant factor in case of R10 series of preferred numbers is
1.06
1.12
1.26
1.58
When a helical compression spring is cut into halves, the stiffness of the resulting spring will be
Same
Double
One-half
One-fourth
The creep in the belt is due to
Effect of temperature on belt
Material of belt
Unequal extensions in the belt due to tight and slack side tensions
Stresses beyond elastic limit of belt material
Stress concentration is caused due to
Variation in properties of material from point to point in a member
Pitting at points or areas at which loads on a member are applied
Abrupt change of section
All of the above
Stress concentration factor is defined as the ratio of
Maximum stress to the endurance limit
Nominal stress to the endurance limit
Maximum stress to the nominal stress
Nominal stress to the maximum stress
Which is correct statement?
A member made of steel will generally be more rigid than a member of equal load carrying ability made of cast iron
A member made of cast iron will generally be more rigid than a member of equal load carrying ability made of steel
Both will be equally rigid
Which one is rigid will depend on several other factors
When a circular beam of diameter d is subjected to a shear force F, the maximum shear stress induced will be
4F/ πd²
6F/ πd²
8F/ πd²
16F/ 3πd²
A bolt of uniform strength can be developed by
Keeping the core diameter of threads equal to the diameter of unthreaded portion of the bolt
Keeping the core diameter smaller than the diameter of the unthreaded portion
Keeping the nominal diameter of threads equal to the diameter of unthreaded portion of the bolt
None of the above
The plasticity is the property of a material which enables it to
Regain its original shape after deformation when the external forces are removed
Draw into wires by the application of a tensile force
Resist fracture due to high impact loads
Retain deformation produced under load permanently
The fatigue life of a part can be improved by
Electroplating
Polishing
Coating
Shot peening
The building up of worn and undersized parts, subjected to repeated loads by electroplating is
Best method
Extremely hazardous
Has no effect as regards fatigue strength
Cheapest method
A self locking screw has
Fine threads
Course threads
Coefficient of friction is greater than tangent of load angle
Hole for inserting split pin
Rankine Gordon formula for buckling is valid for
Long column
Short column
Short and long column
Very long column
The dedendum is the radial distance from the
Pitch circle to the top of a tooth
Pitch circle to the bottom of a tooth
Top of a tooth to the bottom of a tooth
Addendum circle to the clearance circle
The speed of the sprocket reduces as the chain pitch __________ for a given number of teeth.
Increases
Decreases
Remain same
None of these
The bending stress in a curved beam is
Zero at the centroidal axis
Zero at the point other than centroidal axis
Maximum at the neutral axis
None of these
Eulers formula for a mild steel column is not valid if the slenderness ratio is
90
60
120
100
Crowning on pulley helps
In decreasing the slip of the belt
In increasing the slip of the belt
To keep the belt in centre on a pulley while it is in motion
To increase pulley life
Which one of the following is a positive drive?
V-belt drive
Rope drive
Crossed flat belt drive
Chain drive
The permissible stress in the fillet weld is 100 N/mm². The fillet weld has equal leg lengths of 15 mm each. The allowable shearing load on the weldment per cm length of the weld is
7.5 kN
10.6 kN
15 kN
22.5 kN