314 



absence of better information, it is assumed here to hold also for nonsta- 

 tionary flow. 



The coincidence of the directions of principal stresses and strain, 

 usually included among the rules describing plastic behavior, has not been 

 stipulated here because it is automatically secured by the axial synmetry. 



Before attempting a solution, it is desirable to recast Eqs. (l) 

 to (11) in a more workable form. Using the reduced engineering stresses S, 

 and 3 exclusively, and combining seme of the foregoing equations we get 



3: 





(12) 



(13) 



where 





ClA) 



6,N 5.^- 5,5,-1, (15) 



where C3:^and d are given by Eqs. (3) and (4). With the above equations 

 should be included Eqs. (9) and (10) giving the strains. 



