Calculation of load distribution in stiffened cylindrical shells Page: 4 of 70
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N.A 0.A Technical lMem'ortahdm to., '66 3
and the transverse etiffeners (bulkheads). Whe longitudi
na-l -stirfenors. are .aesumu.t,q b.o inside -and attached to
the skin, while -the transverse dtiffeners, assumed as par-.
1ilol, may eitherr be attached to the shoot (for example,
in the neighborhood of the positions of load application)
or attached only to the inner sides of the stringers. Who
bhlkheads may be in tho form of frameworks or flexurally
rigid solid rings. The shell rose section is assumed to
be simply connectod, although the method may be extended
to. multiply connected systems. For the sake of simplic-
ity, we shall restrict ourselves to cylindrical shells
since the disturbances of the elementary stress condition
in monocoque fueolages and wings almost always extend over
individual. small portions, which may approximately be con-
siderod as of cylindrical shape.
The transverse stiffening walls are denoted in the
positive x direction by 0, 1, ..., k, ..., n (fig. 2).
Thcy divide the system into bays, each of which is denoted
by the stiffener number on its right. The stringers are
numbered going around the positive direction from some ini-
tial position 1, 2, ..., 3, ..., m, the peripheral por-
tions lying between the atiffeners (shoot or bulkhead por-
tions) being deonotoed by the higher stringer number as sub-
. script. All goomotrical and structural magnitudes in the
shell rocoivo a double subscript J,k corresponding to
their position.. If the transverse section possesses axes
of symno try, then synmmetrically lying magnitudes are given
the sano subscripts.
For the computation of the shells under consideration,
the following simplifoied model is used as a basis. The
bulkhoads take up forces that lie in the bulkhead planes
only. The stringers are assumed to be hinge-conne noted to
the bulkheads. In the case of stringers that go through
and possosd great flexural stiffness of their own, the ad-
ditional stresses may be taken into account, as in the
case of frameworks, by the introdution of nodal-point'mo-
monte as additional station rodundancies. In the skin it-
self a pure membrane-trpe of stress distribution is assumed.
The most.nimportant simplification is in connection:
with the stress dietribtion in the skin and stiffenera.
The transverse stiffeners are, for the moment, assumed to
be attached to the skin; a generalization will be qonsid-
ered under section III, 4. Normal stresses will then be
transmitted by the stiffeners only, so that the sheet pan-
els act as pure tension fields. The normal stiffness of.
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Ebner, H & Koller, H. Calculation of load distribution in stiffened cylindrical shells, report, June 1, 1938; (digital.library.unt.edu/ark:/67531/metadc63311/m1/4/: accessed August 18, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.