TORSION
1. Define the term 'torque'.
The product of
turning force, and the distance between the point of application of the force,
and the axis of the shaft is known as torque..
2.
What
are the assumptions made in theo ry of torsion.
(i)
The material
of the shaft is uniform throughout.
(ii)
The twist
along the shaft is uniform.
(iii)
The shaft is
of uniform circular se ction throughout.
(iv)
Cross-Sections
of the shaft, whic h are plane before twist, remain plane after t wist.
3.
Define
the term polar modulus.
Polar
modulus is defined as the ratio of the polar moment of inertia to the radius of
the shaft.
Zp = J/R
4.
Define Torsional Rigidity.
We
know the torsion equation
T/J = C?/l
? = Tl/CJ
Since C, l and J are constant for a given
shaft, ? (angle of twist) is directly proportional to T (torque). The term CJ
is known as torsional rigidity.
5. Define the term 'equivalent bending moment'.
Equivalent
bending moment (Me) may be defined as the bending moment which will produce the
same direct stress as produced by the bending moment and the torque acting
separately.
6. Define the term 'equivalent twisting moment'
The equivalent
twisting moment (Te) may be defined as the torque which will produce the same
maximum shear stress as produced by the bending moment and the torque
separately.
7. Why
hollow circular shafts are preferred when compared to solid circular shaft?
i). The torque transmitted by the hollow shaft is grater than the solid
soft.
ii). For same material, length and given torque, the weight of the
hollow shaft will be less compared to solid shaft.
8.
What is meant by spring?
Spring is a
device which is used to absorb energy by very large change in its form without
permanent deformation, and then release the same when required.
9.
What is meant by stiffness?
The stiffness of the spring is defined as the load required to produce
unit deflection.
10. What are the different types of springs?
i). Torsion
spring ii). Bending spring
11. What is torsion spring?
A torsion spring is the one which is subjected to a twisting moment and
the resilience is mainly due to torsion.
12. What is bending spring?
A bending spring is one which is subjected to bending only and
resilience is mainly due to bending.
13.
What are the stresses are induced in the spring?
i). Direct stress
ii). Torsional stress iii). Bending stress
14. Explain the
springs in parallel.
When two springs
are joined in such a manner that they have common deflection they are said to
be connected in parallel.
15. Explain the springs in series.
In many
situations, the combination of two or more springs either may be connected in
series or parallel are required.
16. What are the applications of closed
coiled helical spring?
The
closed coiled helical springs are used in Railway wagons, cycle seating,
pistols, brakes etc.
17. Differentiate between close coiled and
open coiled helical springs.
Close-coiled spring
a) Adjacent coils are very close to each other
b) Only tensile load can carry
c) Helix angle is negligible
Open- coiled spring
a) Large gap between adjacent coils
b) Tensile and compressive loads can carry.
c) Helix angle considerable
18. What is meant by stiffness of a spring
and write an expression for it.
Stiffness (K) of
a spring is a measure of its capacity and is defined as the load required
producing unit deflection. K = P/d Where, P -
Load, d - Deflection
19. What is buffer spring?
Buffer spring is
mostly used in Railway wagons. The shock between two colliding bodies may be
softened or cushioned by means of buffers.
20. Write an
expression for the angle of twist for a hollow circular shaft with external
diameter D, internal diameter d, length l and rigidity modulus G.
Angle of twist q = Tl/GJ Where, T- Torque
J-Polar moment of inertia J = p[D^{4 -} d ^{4}]/32
21.
Why
hollow circular shaft are preferred when compared to solid circular shafts?
a) The torque transmitted by the hollow shaft is
grater than the solid shaft.
b) For same
material, length and given torque, the weight of the hollow shaft will be less
Compared to solid shaft
22. Write down the equation for shear strain
energy of closed coiled spring.
Shear strain energy U= [f^{2} |
_{s}/4C] x volume of the spring |
Where f_{s} -
Shear stress, |
C- Modulus of rigidity |
23.
What
kind of stress introduced when an axial load acts on an open coiled spring?
Bending stress and Shear stress
24.
What
is meant by spring constant or spring index?
Spring constant is the ratio mean diameter of
the spring to the diameter of the wire.
25.
What
kind of stress induced when an axial load acts on a close coiled spring.
Shear stress.
26.
Explain
leaf springs?
Leaf springs are
called as laminate springs are commonly used in carriages such as Cars, Lorries
and Railway wagons.
27. What are the applications of leaf spring?
Leaf springs are
commonly used in carriages such as Cars, Lorries and Railway wagons shocks of
vehicles given unpleasant felling to the passengers and hence springs are used
to absorb such shocks.
28. What types of stresses are caused in a
beam subjected to a constant shear force?
Vertical and horizontal shear stress.
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