ESDU 80040:2012

ESDU 80040 provides computer programs to calculate the lower
natural frequencies and mode shapes for axial and circumferential
vibration of circular-cylindrical, uniform shells with either
uniform stringer stiffeners or uniform ring stiffeners, or a
combination of both types of stiffener, which can be modelled as
homogeneous orthotropic shells. Such modelling is usually
applicable when the stringers are uniformly and closely pitched
around the shell circumference and the rings are uniformly and
closely pitched along the shell longitudinal axis. The results
obtained should be used as guidelines to practical shell behaviour.
Two programs, ESDUpac A8040 and ESDUpac B8040, are given: ESDUpac
A8040 applies to initially unstressed shells or to shells having
initial stress due to static axial and/or pressure loading with all
combinations of clamped, shear diaphragm and free shell end
conditions while ESDUpac B8040 applies to an initially unstressed
shell using either the discrete stiffener or smeared stiffener
model but only with shear diaphragm end conditions. The format of
the input to and output from the programs is illustrated by worked
examples. In addition, equations are given for estimating the
torsional natural frequencies and mode shapes for all combinations
of end conditions except clamped/shear diaphragm.