7. 6 Figure 7.1 with a comparison of normal loading condition and failed condition. Any such loss of panels, of course, transfers the load of the failed panel(s) to adjacent panels and stiffeners. Thus, to maintain the integrity of the remaining structure in the given scenario, each panel must be able to support twice the load normally applied to it without yielding. Additionally, a hole or crack in a panel destroys the pressure seal that the panel formed. If a section of the outer hull has failed, one of the compartments between the inner anJ outer hulls will be evacuated. Thus, a pressure load will be imposed upon that portion of the inner hull covering the compartment as well as the bulkheads that form the walls of the compartment. See Figure 7.2 for a schematic description of this kind of failure. The additional loading in this case does not behave ,as the previously defined hoop stress. Rather, sections of the hull and bulkheads involved may be considered plates under uniform transverse load clamped on all edges. The clamped plate loading produces large bending stresses which are assumed to add linearly with the tensile hoop stresses. The approximation involved in the assumption of linearity is here conservative, as the tension loading tends to decrease the bending moments due to transverse deformation of the plate. If the initial loading were compressive, the system would be highly nonlinear and the assumption of linearity would lead to unconservative results (7.1). A panel failure in either the inner hull or one of the bulkheads has less severe consequences in that the additional load produced is confined to adjacent panels as discussed above. For detailed stress analyses associated with the various loading conditions,see Sections VII.4.2, VII.4.3, and VII.4.4. The damage potential of meteoroid impact is an area that was studied intensively in the early 1960's (7.2) (7.3) (7.4) . For our purposes it is sufficient to define the likely maximum severity of attack and to determine that the hull will not be seriously damaged under such attack. Section VII.5 and Appendix VII.C discuss this problem in some detail.
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