Use shell elements to model structures in which one dimension (the
thickness) is significantly smaller than the other dimensions and in which the
stresses in the thickness direction are negligible.
A structure, such as a pressure vessel, whose thickness is less
than 1/10 of a typical global structural dimension generally can be modeled
with shell elements. The following are examples of typical global dimensions:
the distance between supports,
the distance between stiffeners or large changes in section thickness,
the radius of curvature, and
the wavelength of the highest vibration mode of interest.
Abaqus
shell elements assume that plane sections perpendicular to the shell midsurface
remain plane. Do not be confused into thinking that the thickness must be less
than 1/10 of the element dimensions. A highly
refined mesh may contain shell elements whose thickness is greater than their
in-plane dimensions, although this is not generally recommended—continuum
elements may be more suitable in such a case.