7. 28 Secondly, the loading conditions sustained in the event of an outer hull failure is not separate and distinct from the normal loading. It is, rather, a special case of the normal stress versus thickness relation. Recall the discussion of adjacent panel overstress in the failure mode that was presented in Section VII.2.4. The Fail Safe criterion then demands that the design point on the stress versus thickness curve is chosen such that the assumed maximum overstress of 2.1 times the normal stress may be accommodated without yielding the plate. The analysis will now proceed as before considering only the cylindrical section and assuming a lg centrifugal acceleration. See Appendix VII.E for the determination of the relative mass per unit area contributed by the hull, shield, and bulkheads. p 0 ¾uu MShield atmospheric pressure= 40,530 N/m 2 7870t kg/m 2 5000 kg/m 2 2158 kg/m 2 105m R2P2 - !Q2 ~ -t2 [7870t2(9.807) + 21582(9.807) + 5000(9.807) + 40,530] 105 [98 340t + 89,565] ½ ' 2 l.0326xl0 7 + 9.4043xl0 6 !_ t2 This equation defines the outer hull stress versus thickness relation. Typical results are plotted in Figure 7.9. VII.4.5: Bulkheads: Sections VII.4.3.1 and VII.4.4 used an approximation that set the bulkhead thickness equal to the thickness of the hull plate then being discussed. This was useful in obtaining stress versus thickness relations for each hull independent of the other structural components. Since it was thought that the bulkhead thickness would be less than but comparable to the hull thickness, the error
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