The effect of cylinder length can be observed from Cases 3 and 4 



and 5 and 6, all of which have the same t/D ratio of 0.037 but differ- 



o 



ent effective lengths. Cases 3 and 4 had an L/D ratio of 2.35, and 

 Cases 5 and 6 had an L/D ratio of infinity. For the out-of-round 

 cylinders (Cases 4 and 6), the shorter cylinder had a predicted 

 increase in implosion strength of 53% over that of the infinitely long 

 cylinder. Experimentally, the increase in strength was 41%. 



Displacement Behavior 



The predicted deflected shapes for free-support and simple- 

 support specimens are shown in Figures B-18 and B-19. For the free- 

 support cylinder (Figure B-18), the predicted shape is a fair approxi- 

 mation of the experimental shape. It should be noted that the pressure 

 level for the experimental shape is near implosion at 400 psi (2.8 MPa) 

 where the analytical shape is at implosion at 346 psi (2.4 MPa). For 

 the simple-support cyhnder (Figure B-19), the comparison is good. 



The predicted radial displacement behavior as a function of pres- 

 sure is shown in Figures B-20 and B-22. Comparison of the experi- 

 mental to analytical behavior is quite good. For the out-of-round 

 cylinders, note that the predicted implosion pressures using the strain 

 or stress criteria are approximately the same. 



A large difference in ultimate radial displacement was observed 

 between perfect and out-of-round specimens. For cylinders of t/D - 

 0.037 (Figure B-21), the experimental out-of-round cylinder showed 

 w = 0.508 inch (13 mm), while the perfect cylinder had w = 0.08 inch 

 (2 mm) - a 6.4-fold increase. For specimens having the same t/D 

 ratio of 0.037 but different end-support conditions (Figures B-21 and 

 B-22), the free-support cylinders showed an ultimate displacement of 

 w = 0.508 inch (13 mm) compared to the simple- support cylinders of 

 w = 0.185 inch (5 mm) - a 2.7-fold increase. 



78 



