The stress analysis of a central transverse crack in a stiffened orthotropic panel under tension is treated in this paper. The existing analytical techniques for the isotropic problem of a crack in an infinite strip, based on the well-known Schwarz alternating method for multiply connected domains, are applied to the present orthotropic problem. The ratio of stress-intensity factors for the finite plate to that of the infinite plate is obtained as a function of the crack length. The results are compared with the isotropic solution.

A governing design synthesis relationship is derived for the primary structural weight of membrane-type pressure vessels. The structural efficiency is associated with the configuration and the failure law characterizing the material used, and it is this factor which is examined in some detail. Closed pressure vessels of various shapes utilizing isotropic and anisotropic materials of monolithic and filamentary construction are analyzed to establish optimum designs and then compared to establish relative structural efficiencies.

The theorems of limit analysis are applicable to an approximate theory if, and only if, the approximate equilibrium and strain-rate-velocity relations are such that the principle of virtual work holds between them. A theory for which this is true may be called “consistent.” Such a consistent theory is developed for shallow shells of revolution, and the methods of limit analysis are applied to particular cases of shallow parabolic and conical shells under normal and axial loads. Bounds are obtained on the plastic interaction curves using the two-moment, limited-interaction yield curve.