increases. Tests on larger scale models can be utilized to study this 

 effect also. 



The problem of adequately penetrating and closing cylindrical 

 pressure hulls of con^josite construction is another large problem area. 

 Here again, the results of these tests are encouraging. Since the two hull 

 penetrations and both end closures showed no ill effects after 12,000 cycles, 

 there is reason to believe that properly designed penetrations and end 

 closures should not affect the fatigue life of composite structures. 



If further cyclic tests substantiate the fairly promising results 

 of these preliminary tests, composite construction will definitely show 

 promise as a method of fabricating deep submergence pressure hulls. 



RECOMMENDATION 



The fatigue strength of large-scale composite cylinders should be 

 investigated to develop a correspondence between scale and fatigue char- 

 acteristics. 



ACKNOWLEDCMENTS 



The author wishes to express his appreciation for the contributions 

 of Mr. Martin A. Krenzke and Mr. Peter M. Palermo who supplied the test 

 data, Mr. Nicholas G. Laios of the Naval Research Laboratory who conducted 

 the second static test of Model DSRV-IF, and Mr. Jack R. Pohlman of the 

 Southwest Research Institute who conducted the cyclic tests. 



