7. 3 imposed during spin-up and pressurization which will never be repeated in the operational life of the structure. Finally, damage incurred to the structure may alter the loading condition and locally increase its severity. VII.2.2: Normal Operations: In the category of normal operational loads, both static and dynamic loads must be examined. The static loads are imposed by the specified atmospheric pressure as well as by the centrifugal acceleration applied to masses within the hull to simulate gravity. These latter loads might be termed "equivalent pressure" loads. In addition, each hull as well as the bulkheads attached to the hulls applies a load equal to the product of its own mass per unit area and the imposed centrifugal acceleration. This is yet another "equivalent pressure" type load. The above con- 'tributions cause a hoop stress to be developed in sections of the hull perpendicular to the spin axis. If the total force per unit area applied to the hull from both atmospheric pressure and "equivalent pressure" forces is known, the hoop stress in the cylindrical section, as developed in Appendix VII.A, is given by: RF 0 e = t where R = radius, F = force/unit area, and t = hull thickness. The hoop stress in the endcap sections is, in general, given by: oe = ¥t The stress in the direction parallel to the spin axis is due primarily to the atmospheric pressure force. For the general capped pressure vessel this stress is given by: 0 X RF = _p_ 2t where Fp = atmospheric pressure load. Now the total load is not an istropic pressure load but rather a combination of pressure load which is isotropic in distribution and centrifugal load which is directed perpendicular to the spin axis. This condition alters the stresses predicted for the endcaps by the above simple relations. For the purposes of this analysis,
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