• Version
• 157 Downloads
• 1.29 MB File Size
• 1 File Count
• January 23, 2017 Create Date
• January 23, 2017 Last Updated

National Advisory Committee for Aeronautics, Technical Notes - Stress Distributions Caused by Three Types of Loading on a Circular Semimonocoque Cylinder with Flexible Rings

Equations are derived for the stress distributions caused by three
types of loading on infinitely long, circular, semimonocoque cylinders
with flexible rings. These external loads can be said to lie in the
sheet-stringer surface of the cylinder; that is, they have no radial
components. The results, given as formulas for the stringer loads and
shear flows in the shell, are of use in the stress analysis of circular
semimonocoque cylinders with cutouts. In order to facilitate this appli-
cation, the formulas can be used to construct tables of influence coef-
ficients giving stringer loads and shear flows in the neighborhood of
each particular external load due to a unit magnitude of that load.

An airplane of semimonocoque construction usually has various
openings for doors, cargo hatches, landing-gear mechanisms, and other
purposes. The structural design of the airplane near such openings
requires knowledge of the stress distribution about cutouts in semi-
monocoque shells. Stress analysis of semimonocogue structures with
cutouts is beyond the scope of engineering beam theory because stress
concentrations occur in the neighborhood of the cutouts. It is for
this reason that more powerful methods of analysis are sought.

A method for the stress analysis of sheet-stringer panels with cut-
outs has been presented in reference 1. The method is based on the
idea introduced by Cicala (ref. 2) that the effect of the cutout can be
reproduced by superposing certain perturbation stress states on the
stresses which would occur in the structure without a cutout. Three
types of "unit perturbation solutions" were obtained,m md it was shown
how these solutions could be used to handle cutouts in sheet-stringer
panels under axial loads.

It is evident that this approach can be extended to the analysis of
stresses around cutouts in circular semimonocogue cylinders. In order
to make the extension, however, perturbation solutions for this type of
structure must be developed. Accordingly, the purposenof this report is
to derive the perturbation solutions for an infinitely long circular
cylinder of semimonocogue construction.