Determine the minimum thickness required:

A thin spherical shell of 2 m diameter is subjected to an internal pressure of 1.5 N/mm². If the allowable tensile stress of the material of the shell is equal to 125 N/mm², determine the minimum thickness required.

Solution

Diameter of the shell, d = 2 m = 2000 mm.

Internal pressure, p = 1.5 N/mm².

 Permissible tensile stress = 125 N/mm².

If thickness of the shell is t.

After that, we have,

125 = pd /4t = 1.5 × 2000/4t

∴          t = 1.5 × 2000 /4 × 125= 6 mm

∴ Minimum thickness required = 6 mm.