CONCLUSIONS 



1. Test results indicate that the stresses and deformations of an oval cylinder stiffened 

 by elastic rings cannot be predicted by an equivalent circular cylinder solution based on the 

 same radius of curvature. 



2. Based on the following results, it appears that a ring- stiffened oval cylinder designed 

 for deep-depth operation is a very inefficient structure when compared with a ring-stiffened 

 circular cylinder: 



a. Plastic hinge collapse pressures of 2356 and 3049 psi were computed for the 

 large-radius and small-radius sections of the oval cylinder, respectively. These 

 pressures were computed by considering an equivalent circular cylinder with the 

 same local radius oF curvature as the oval cylinder which had a collapse pressure 

 of only 1670 psi. 



b. The weight-displacement ratio of the oval cylinder was 0.598- Based on 

 least-weight calculations, a circular cylinder with the same weight-displacement 

 ratio and fabricated from the same material (HY-100 steel) would have a collapse 

 pressure on the order of 4000 psi as compared to the collapse pressure of 1670 psi 

 for the model. 



3. Additional studies, based on theoretical knowledge now available, may indicate that 

 for shallow-depth operation the oval cylinder may lend itself to a better distribution of cargo, 

 equipment, machinery, and personnel and may accommodate more missile tubes than a ring- 

 stiffened circular cylinder. 



4. Test results indicate that the theoretical solution recently developed at Polytechnic 

 Institute of Brooklyn will yield good predictions for the deformations and stresses of ring- 

 stiffened oval cylinders with uniform shell thickness. 



5. In the ring-stiffened oval cylinder tested, critical stresses were reduced as much as 

 50 percent by incorporating tubes parallel to the minor axis of the oval cross section. How- 

 ever, thicker walled tubes would be required for the oval cylinder than for an equivalent 

 circular cylinder of the same radius of curvature and dimensions. 



ACKNOWLEDGMENTS 



The author is indebted to Messrs. J.G. Pulos and Kenneth Hom for their guidance 

 and suggestions. 



The author would also like to acknowledge the close cooperation received from 

 Polytechnic Institute of Brooklyn in the theoretical phase of this study. 



