Figure C-6. Two-dimensional model of end closures and hydraulic 

 load applicator. 



CONCLUSIONS 



Serious stress concentrations inave been found ( 1 ) at tlie base of tlie 

 heads of tie rods, (2) in the shape transition zone at the end-closure flange, 

 and (3) around the shear-pin holes in the segmented-wall laminae. These 

 stress concentrations occur at locations where failure was previously initiated 

 in the acrylic pressure vessel models during hydrostatic testing. If full-scale 

 pressure vessels of design similar to that of the models tested are built, these 

 stress concentrations must be either eliminated or their severity taken into 

 consideration during the vessel design. 



84 



