Figure 12 - View of Axisymmetric 



Crease in Outer Shell of 



Model OV-1 



Figure 13 - View of Overall 

 Failure of Model OV-2 



Pressure -strain plots for gages located in the region of failure of 

 Model OV-1 are presented in Figures 14 and 15. An examination of these 

 plots shows that at the higher pressures approaching collapse the strains 

 could conceivably have been on the order of 20, 000 to 30, 000 |jiin./in, and 

 possibly higher. Similar observations were also noted during the test of 

 Model OV-2. 



Stress -sensitivity factors calculated from the analysis of Reference 

 3 are given in Figure 7, which shows that the most critically stressed re- 

 gions are located on the inner surface of the outer shell at the toe of the 

 webs. Based on the theoretical stresses at this location, yielding accord- 

 ing to the Hencky-Von Mises criterion would initiate at pressures of 7500 



