This document discusses different types of springs used in mechanical engineering. It covers helical springs and leaf springs. For helical springs, it provides the nomenclature and expressions to calculate maximum shear stress, spring deflection, and stiffness. It also includes examples of calculations for these values. For leaf springs, it discusses their applications in vehicles and provides the expression to calculate maximum bending stress and central deflection, along with example calculations.

1. CE8395
STRENGTH OF MATERIALS FOR
MECHANICAL ENGINEERS
By,
Dr.S.SURESH,
Assistant Professor,
Department of Mechanical Engineering,
Jayalakshmi Institute of Technology.
UNIT-III-TORSION
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SPRINGS

2. SPRINGS
 Elastic member whose primary function is to deflect
or distort under the action of applied load; it recovers
its original shape when load is released.
 Quality of a spring is judged from the energy it can
absorb.
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3. NOTABLE APPLICATION OF SPRINGS
 To apply forces and to control motions as in brakes
and clutches
 To measure forces as in spring balance.
 To store as in clock springs.
 To reduce the effect of shock or impact loading as in
carriage springs.
 To change the vibrating characteristics of a
members as inflexible mounting of motors.
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4. The springs are of the following two types depending upon the type
of resilience.
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5. (HELICAL SPRINGS)
•A springs made up of a wire coiled into a helix.
•A spring, which is subjected to torsion or twisting
moment only and the resilience is also due to it, is known
as a torsion spring.
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6. NOMENCLATURE OF HELICAL SPRING
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7. W
S = Spring Stiffness (N/m)
The load required to produce a unite deflection is called Spring
Stiffness (N/m)
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8. EXPRESSION FOR MAX. SHEAR STRESS INDUCED IN WIRE
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9. (Expression for Max. Shear Stress induced in wire)
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10. EXPRESS FOR DEFLECTION OF SPRING
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11. (Express for deflection of spring)
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12. Example 1: A closed-coiled helical spring is required to carry a
load of 150 N. If the mean diameter is to be 8 times that of the
wire, calculate these diameter. Take maximum shear stress as
100 Mpa.
Given:
Solution:
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13. Given:
Solution:
EXAMPLE 2: A closed-coiled helical spring of round steel wire 5 mm in
diameter having 12 complete coils of 50 mm diameter is subjected to an axial
load of 100 N. Find the deflection of the spring and the maximum shearing
stress in the material. Modulus of rigidity (C) = 80 Gpa.
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14. Example 3: A closed coiled helical spring of round steel wire
10 mm in diameter having 10 complete turns with a mean
diameter of 12 cm is subjected to an axial load of 200 N.
Determine: (i) The deflection of the spring (ii) Maximum shear
stress in the wire, (iii) stiffness of the spring.
Take C=8x104 N/mm2.
Given:
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15.  Deflection
 Shear Stress
 Stiffness
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16.  These are also called laminated springs.
 The leaf springs are widely used in Railway wagons, Coaches
and Road vehicles.
 These are used to absorb shocks, which give an unpleasant
feeling to the passengers.
 The energy observed by a laminated spring, during a shock,
is released immediately without doing any useful work.
 Types are (i) Semi-elliptical (ii) Quarter-elliptical
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17. EXPRESSION FOR MAX. BENDING STRESS AND DEFLECTION
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18. 18

19. Central Deflection of the Spring = δ
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20. EXAMPLE 1: A laminated spring 1m long is made up of plates each 50 mm
wide and 10 mm thick. If the bending stress in the plates is limited to
100 MPa, how many plates are required to enable the spring to carry a
central point load of 2 KN. If modulus of elasticity for the spring material is
200 GPa, What is the deflection under the load?
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21. EXAMPLE 2: A leaf spring to be made of seven plates 65 mm wide and
6.5 mm thick. Calculate the length of the spring, so that it may carry a
central load of 2.75 KN, the bending stress being limited to 160 MPa. Also
calculate the deflection at the centre of the spring. Take E for the spring
material as 200 GPa.
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