What is the thickness of the shell of a bomb calorimeter of spherical form of 10 cm inside diameter if the working stress is σMPa and the internal pressure is σ/2 MPa? [Take 21/3 = 1.26]
at r = a, σθ is maximum
Thickness of bomb shell
The radial stress in a thin spherical pressure vessel is
Hoop stress in a thin cylinder of diameter dand thickness t subjected to pressure p will be
Due to fluid pressure p in the cylinder bursting force = p x d x L
This is resisted by thickness of cylinder Resisting force = σh(2t x L).
Resisting force = Bursting force
where σh = hoop stress
p = internal fluid pressure
d = Diameter of cylinder
t = Thickness of cylinder
Longitudinal stress in a thin cylinder of diameter d and thickness t subjected to pressure p will be
A thin cylindrical shell of internal diameter d and thickness ‘t’ is subjected to internal pressure ‘p’. The change in diameter is given by
In above case the longitudinal strain is
A thin cylindrical shell of diameter d, length L and thickness t is subjected to an internal pressure p. What is the ratio of longitudinal strain to hoop strain in terms of Poisson’s ratio (1/m)?
The volumetric strain in case of a thin cylindrical shell of diameter d, thickness t, subjected to internal pressure p is
The design of thin cylindrical shells is based on
Since hoop stress (σh) > Longitudinal stress (σL). Hence to have safe design, hoop stress is considered.
The commonly used technique of strengthening thin pressure vessels is
The commonly used technique of strengthening thin pressure vessels is wire winding. The wire is wound under tension, thus putting the walls of the cylinder under compression. This way, the cylinder is pre-stressed.