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BSTRACT: In this experiment, stresses related to the selected points on the surface of a thick cylinder have
been measured using the strain gauge indicator. Cylinder was subjected to an internal pressure
varying gradually and then corresponding stress values was measured. Besides all these steps,
experiment also involves the calculation of Principal Strains and Stresses based on strain gauge
data of thick cylinder at 450psi internal pressure.
INTRODUCTION: Thick walled Cylinders are widely used in chemical, petrochemical, military industries as well as
in nuclear power plants. They are usually subjected to high pressures and temperatures which
may be constant and cycling so being a mechanical engineer, the analysis of stress distribution
in a thick cylinder is of considerable practical importance in pressure vessels and in other
important applications of thick cylinders. Another important aspect of this experiment was to
able the students to measured and then calculates the principal stresses and strains in thick
We know that there are two types of cylinders, one is thin walled and other is thick walled
cylinder. For the thin-walled assumption to be valid the cylinder must have a wall thickness of
no more than about one-tenth of its radius. If the cylinder to be studied has a
ratio of less
than 10, the thin-walled cylinder equations no longer hold and it is a thick walled cylinder.
The objective was achieved by using rectangular strain gauge rosette and strain gauge
Fig 01, Rectangular Strain Gauge Rosette Fig 02, typical Strain gauge indicator
PROCEDURE: Given below steps were followed during the procedure of experiment.
1. The experiment was done on that thick cylinder which had already placed rosettes on it
at different locations.
2. First of all, the rosette which was located at θ = 1800 to the pressure gauge & z=0, was
connected to indicator, so that strain could be measured at this location.
3. Then using …………, the internal pressure was gradually increased and strain was
measured at different values of internal pressure.
4. By repeating the same steps for other location rosettes, strain was measured at a four
different locations on thick cylinder.
5. Using formulae theoretical values of strain was calculated and compared to observe
OBSERVATIONS & CALCULATIONS:
Table No. 1 Thick Cylinder Strain Gage Data
Strain Pressure (psi)
50 100 150 200 250 300 350
θ = 180o , z=0
θ = 30o , z=0
εa 4 5 6 7 8 10 11
εb 7 14 20 25 31 36 42
εc 11 20 30 40 49 58 67
θ = 0o Centre of
θ = 0o Close to weld of 2 regions
DISCUSSIONS: The aim of the experiment was to measure the strain at different locations. The objective was
achieved by using strain gauge rosettes and strain indicator.
General applications of thick walled cylinders include high pressure reactor vessels used in
metallurgical operations, process plants, air compressor units, hot water storage tanks,
pneumatic reservoir, hydraulic tanks etc. They are often subjected to extreme conditions of
high pressure and temperatures of working fluids.