

Figu 



re F-2. Inspection of joints for presence of bubbles and undercuts at 

 Swedlow Inc. 



capsule's critical pressure or serve as sources for incipient cracks under 

 hydrostatic loading, the substantial decrease in number of bubbles in 

 capsules 1 , 2, and 3 resulted in joints with much better transparency and 

 an improved all around appearance. 



Strength of Joints 



The quality of the joints was checked for each capsule by bonding 

 together four blocks of 1 2 x 4 x 2.5-inch acrylic plastic into two 1 2 x 8.1 25 x 

 2.5-inch joint specimens with the same batch of adhesive used on the capsule 

 and in the same controlled environment where capsules were bonded. These 

 joint specimens accompanied the capsule to the oven for annealing. After 

 the capsule was completed and ready to be delivered to the customer, 

 12 tensile test coupons were cut from each joint specimen, with the joint 

 in the center of each coupon. All of the test coupons were tested to destruc- 

 tion, and the ultimate tensile strength of the joints was noted. 



209 



