The document discusses the characteristics and functions of springs, highlighting their ability to absorb and release energy and restore mechanisms against external forces. It compares closely coiled and open coiled helical springs in terms of pitch, helix angle, and load capacity. Additionally, it describes thin cylindrical shells, their applications, and stresses resulting from internal pressure.

1. SPRINGS AND THIN
CYLINDERS
UNIT-V

2. INTRODUCTION
• A spring is a device which can undergo considerable amount of
deformation without permanent distortion. The general purpose
of all kinds of springs is to absorb energy and to release it as and
when required. Springs are also used to provide a means of
restoring various mechanisms to their original configurations
against the action of some external force.

3. COMPARISON OF CLOSELY COILED HELICAL SPRING
AND OPEN COILED HELICAL SPRING
Closely coiled helical spring Open coiled helical spring
1) The pitch of the coil is very small. The pitch of the coil is large.
2) The gap between the successive turn
issmall.
The gap between the successive
turnis large.
3) The helix angle is less (7o to 10o). The helix angle is more (>10o).
4)
Under axial load, it is subjected to
torsion only.
It is subjected to both torsion and
bending.
5) It can withstand more load. It can withstand less load.

4. APPLICATIONS OF SPRINGS
• Applying forces and controlling motion, as in brakes and
clutches.
• Measuring forces, as in spring balances.
• Storing energy, as springs used in watches and toys.
• Reducing the effect of shock and vibrations in vehicles and
machine foundations.

5. Thin cylinders
• Shells are engineering components having greater strength by
virtue of their curved shape. A thin cylindrical shell refers to a
hollow cylindrical structure with a relatively small thickness
compared to its radius or diameter. It is essentially a hollow tube
with thin walls.
Example: Pressure vessels, storage tanks, pipelines, and structural
components.

6. CIRCUMFERENTIAL STRESS OR HOOP STRESS
• Consider a thin cylindrical shell subjected to an
internal pressure as shown in the Fig.5.7. As a result
of this pressure, the cylinder may split up in to two
troughs.

7. LONGITUDINAL STRESS
• Consider a thin cylindrical shell subjected to an internal
pressure as shown in the fig As a result of this pressure,
the cylinder may split up in to two pieces.