PLASTIC FAILURE OF CYLINDRICAL SHELLS. 



Tests on Small Cylinders. 



623 



9 



Static tests. — A number of coffee and liousehold milk tins, complete 

 with covers, were half embedded in sand in the same way as was proposed 

 for the tests on the standard cylinders and were then loaded through a 

 x|-inch-diameter steel ball at the mid-section. The loads were applied 

 in small increments by dead weights and at different stages in the test the 



Figa 11. 



)-00 0-02 0'04 0-06 0-08 1-00 \ 

 RAM DISPLACEMENT ■ INCHES 



Static Test on Coffee Tin. 



0-00 0-02 0-04 0-06. 0-09 1-00 1 

 RAM DtSPLACEMENT • INCHES 



Static Test on Milk Tin. 



whole load was removed and re-applied. Typical curves obtained from 

 those tests are shown in l^igs 11, and it is noticeable that there is practi- 

 cally no looping due to the removal and re-application of the load. That 

 was characteristic of all the tests made in the course of the investigation, 

 irrespective of the size or construction of the cylinders. At (b) and (d) in 

 Fig. 2 are shown typical specimens after test ; they are arranged with 

 Taylor's model for comparison and the similarity is marked. 



Fig. 13. 



Cfeas« 



Heavily Kelnforced 

 Tin. 



Dent in Heavily 

 Reinforced Tin. 



The type of failure illustrated in Fig. 2 by Taylor's model can only 

 occur if the ends of the cylinder are free to bend out of their own plane ; 

 if the ends resist bending, tensions will be induced in the shell and the 

 resulting strained shell cannot be developed into a plane surface. 



To examine the effect of end stiffness a series of tests were made on 

 tins in which the normal thin bottom and cover were replaced by steel 



