Let a spherical shell of external radius, Re, and internal radius, Ri, be subjected to an internal fluid pressure p be considered.
Also, an elemental disc of the spherical shell of thickness dr at a radial distance r subtending an angle of dθ at centre is considered (Figure 10.3).
Fig. 10.3 Spherical shell subjected to internal pressure.
Let the radius be increased to (r + u) and the thickness to (dr + du) due to the internal fluid pressure.
Let ec and er be circumferential strain and radial strain, respectively.
From Equation (10.30)