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called a shell of revolution. Shells of revolution are also called
axially symmetric. These shells include cylindrical, conical,
spherical and also ellipsoids, paraboloids and others.
Model of thin-walled shells is based on Kirchhoff-Lava’s
hypothesis:
– rectilinear element that is perpendicular to the middle surface
after deformation remains straight and perpendicular to the
middle surface and does not change the length;
– normal stresses on platforms that are parallel to the median
surface, can be neglected.
The problem of computation of axisymmetrical thin-walled shell
can be solved most simply by assuming that the stresses are
distributed evenly over the shell thickness, bend membranes is
absent. Shell theory, which based on this assumption, called
momentless. To apply this theory certain conditions must be met:
– shell should have smooth shape (no abrupt changes or
distortions thickness);
– boundary conditions should be such that the reactions
were limited to forces acting in the middle surface;
– burden should be distributed smoothly over the surface of
the shell.
In terms of sustainable use of the material of construction
momentless stress state is beneficial. Therefore, the design should
strive to create conditions under which can be implemented
momentless stress state.

9.2 Stresses in axially symmetric thin-walled shell.
Calculation of the strength

Consider axially symmetric thin-walled shell thickness  , which
is under internal pressure p .

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