Figure 26. Segmented-wall acrylic 

 pressure vessel model 

 undergoing internal 

 pressure test. 



Segmented-Wall Vessel 



1. The weakest components of 

 the segmented-wall vessel were 

 found to be the tie-bolts holding 

 the individual laminations of the 

 end-closure retaining ring, as they 

 were the first to fail. An increase 

 in their number or diameter would 

 have probably sufficiently raised 

 the strength of the end-closure 

 retaining ring that it would not 

 fail at lower pressure than the 

 segmented wall of the vessel. 



2. The segmented wall of the 

 vessel failed at a pressure that is 

 only approximately two-thirteenths 

 of the stacked rings. This indicates 

 that the segmented-wall construc- 

 tion is approximately one-ninth 



as strong on weight basis as the 

 stacked-ring wall, since the stacked- 

 ring wall is 24% lighter than the 

 segmented wall per unit length 

 of the vessel. 



3. The failure of the segmented 

 wall appeared to have been triggered 

 at several locations by tensile failure 

 of the individual laminae at the 

 shear pins followed by shearing of 

 the shear pins themselves. 



4. Since the cross section of the individual wall-segment laminae at the shear-pin 

 hole carrying the hoop stresses is identical to the cross section of the stacked 

 ring, and since it takes two layers of segment laminae to provide a complete 

 path for hoop stresses, the difference between bursting pressures of the segmented 

 and stacked-ring walls indicates that the tensile stress concentration around 

 shear pins in the individual segments is probably on the order of 3.3. Subsequent 

 investigation of this stress concentration has, in a large measure, confirmed this 

 (Appendix C). 



32 



