Doubly Curved Shells:

Spherical shell is in fact a special case of a general curved shell with two different radii of curvature. We will now study how the general expression for stresses in a double curved shell is attained.

Assumptions

1. The radii of curvature of the shell are extremely large compared to the thickness of the shell.

2. The shell is incapable of offering any resistance to bending and therefore acts as a thin membrane.

3. The stresses working on the shell are uniform throughout the thickness.

4. The stresses act tangential to the middle surface of the shell.