ABSTRACT 



Test results of a ring-stiffened oval cylinder indicate that the use of the 

 local radius of curvature and dimensions of the oval cylinder in a solution for a 

 ring- stiffened ciTcular cylinder will not yield good predictions for the deformations 

 and stresses. 



Based on the collapse strength of the models tested, it appears that an 

 oval cylinder designed for deep-depth operation is a very inefficient structure 

 compared to a circular ring-stiffened cylinder of the same weight-displacement 

 ratio. 



Test results are compared with results obtained from a theoretical 

 solution recently developed at Polytechnic Institute of Brooklyn for a ring- 

 reinforced oval cylinder. The theory treats the case of a shell with uniform 

 thickness; the model, however, was composed of two different shell thick- 

 nesses. The theoretical results obtained by using the local shell thickness 

 of the test cylinder in the computation showed good agreement with test re- 

 sults for all circumferential stresses and for the axial bending stresses; 

 the lack of agreement for the axial membrane stresses is attributed to 

 using the local shell thickness in the calculations from a theory which is 

 based on constant thickness. 



The critical stresses were found to be much higher for the ring- 

 stiffened oval cylinder tested, than for those of an equivalent circular 

 cylinder based on the same radius of curvature. It was also found that 

 tubes or struts placed parallel to the minor axis of the oval cross section 

 appreciably reduced the magnitude of the critical stresses. 



INTRODUCTION 



The structural research program of the David Taylor Model Basin includes investigations 

 of new and untried pressure-hull configurations.^ A ring-stiffened oval cylinder, for example, 

 may possibly lend itself to a better arrangement of cargo, equipment, machinery, and personnel 

 and accommodate more missile tubes than will conventional structures. Accordingly, a model 

 of such a pressure hull was tested at the Model Basin to compare its structural response and 

 efficiency with that of a ring-stiffened circular cylinder. The test results have provided aid 

 in evaluating the theoretical analysis recently developed at Polytechnic Institute of Brooklyn; 

 in addition, they will assist in guiding future structural research on noncircular pressure hulls. 



References are listed on page 9. 



