PLASTIC FAILURE OF CYLINDRICAL SHELLS. 



629 



15 



there was no flicker of the gauge until 49 lb. per square inch was reached. 

 A third dent had then formed at ^ inch from the second ; that was also 

 slightly unsymmetrical and, with the second dent, formed a left and right 

 hand pair as shown at (c) in Figs 23. The area between those two showed 

 a slight bulge. The next collapse occurred at 62 lb. per square inch when 

 a fourth and much narrower elliptical dent developed ; that was of the 



Figs 23. 



TV 



LA. 



(6) 



rrvn 



\aJ\J 



w 



TU 



U^M 



Devklopment of Failure dubinq Hydrostatic Test 

 ON Stiff-Ended Tin, Half-Filled with Lead. 



same length as the earlier ones but was only 0-6 inch wide. In addition 

 the second and third dents had become hexagonal in outline as shown 

 at (d) Figs 23. Fig. 24 (facing p. 16) shows the final appearance of the 

 specimen. 



Those experiments indicated that a cylinder under extreme hydrostatic 

 pressure will fail by the formation of a single dent if the ends arc flexible 

 out of their plane, but if the ends are rigid, failure occurs by multiple 

 " lobing." If the ends possess a small degree of stiffness it is probable 



