The hoop stresses at the polar plate also show compression on the exterior 

 surface of the hull and tension on the interior. The hoop stresses, both on 

 the exterior and the interior, are smaller than meridional stresses. 



2. The stresses at the equator of the acrylic plastic sphere were barely 

 noticeable. The meridional stresses showed compression both on the outside 

 and on the inside, while hoop stresses showed tension both on the outside and 

 on the inside. The compressive meridional stress was higher on the inside than 

 on the outside surface. The tensile hoop stresses were approximately equal 

 for the outside and inside surfaces of the hull. 



3. The tensile stresses caused by pretensioning of tie rods are so small 

 as to constitute a negligible effect on the distribution of compressive stresses 

 superimposed during hydrostatic pressure tests. 



I 



Notes: 



1. Dimensions of sphere — 15-in OD x 14-in. ID 



2. Material — grade G Plexiglas 



3. Temperature — 65 to 70°F 



4. Loading — 



-200 



100-lb load applied around 

 circumference of polar plate 



0.3 



1.2 



0.6 0.9 



Distance From Penetration Edge (radians) 

 Figure 99. Stresses on the exterior of a 15-inch-diameter capsule under axial 

 compression applied by internally located pretensioned tie rods. 



134 



