Design and Stress Analysis of Extraterrestrial ... - The Black Vault

The value of n for thin cylindrical shells can be determined
apprc~ximately from formula [36]
where
EBs, 3_ES4
ratl 12 (1- 10). •
For all cases studied bhe actual critical pressure is determined
from formula [36]
pA =rl- p
where qI is
the correction factor characterizing the imperfection
of the geometric shape of the shell; n, = 0.65-1.0;
n. is the correction factor characterizing the deviation of shell
material properties from Hooke's law at the moment of stability
loss.
The value of coefficient n2 can be determined from the graph
(Fig. 4.45) where the solid line is plotted for the case OT /a 2
T Hp T-
and the dahes for the case a a aT > 2; critical yield limit is
IP S
NP
The stability reserve of a shell is determined by coefficient N,
which is equal to the ratio of the actual critical pressure pA Kp
to the working pressure ppa' The numerical value of coefficient N
is recommended as no less than 3.0. During hydraulic tests it can
be N =2.5.
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