For this study three structural models, two of aluminum and one of 

 titanium were assembled from machined rings and were tested to determine 

 whether hulls built from separate rings could have collapse strengths 

 comparable to monolithic hulls. This type of hull, consisting of separate 

 rings, would be adaptable to a variety of techniques for attaining longi- 

 tudinal strength and watertight integrity. This report summarizes the 

 results of the tests of these three models . 



DESCRIPTION OF MODELS 



The three models were designated PJ-1S, PJ-1L, and PJ-2. Models 

 PJ-1S and PJ-1L were made from 7079-T6 aluminum alloy and Model PJ-2 from 

 6Al-4Va titanium alloy. Yield strengths of 62,000 and 150,000 psi were 

 used in the design calculations for aluminum and titanium, respectively. 

 Based on these strengths, the models were designed for a collapse strength 

 of 10,000 psi, A value of 10.5 x 10 psi was assumed for the Young's 

 modulus of the aluminum, and a value of 16.0 x 10 psi for the titanium. A 

 Poisson's ratio of 0.3 was assumed for all material. The models are shown 

 in Figure 1, and relevant dimensions are given in Figure 2. 



The aluminum models (PJ-1S and PJ-1L) had rectangular inside frames 

 and heavy shell segments of uniform thickness. The typical bay weighed 

 67.9 percent of its displacement weight in sea water. The area per unit 

 length of the hull section was obtained by allowing the average two- 

 dimensional Hencky-Von Mises stress to reach about 62,000 psi at a pressure 

 of 10,000 psi. A highly stable shell structure is required to permit 



utilization of the full -yield strength of the material. To this end, the 



4 

 frames were designed for a general-instability pressure of about 30,000 



psi. A short frame spacing was selected to minimize bending in the shell 

 due to hydrostatic loads and to provide a high elastic-shell buckling 

 strength. Model PJ-1S was 1.7 diameters long, representing a finite com- 

 partment length, and was closed at the ends with flat aluminum plates; 

 Model PJ-1L was four diameters long, approximating a semi -infinite cylinder, 

 and had hemispherical end closures. Models PJ-1S and PJ-1L were designed 

 to evaluate the effect of bulkhead spacing. Both models had identical 

 typical bays and had grooves at each frame. These grooves were filled with 



