369 



In other vords, in the case of impulsive loading the diaphragm profile has 

 a kink vAiich is propagated inward with a velocity R^u?^ (x+'X? . 

 In the c ase of an exponential wave of the form 



^<,Cfc;» )?^e'^'^^ ,t>a, 



we have 



(31) 



] 



In the limiting case of in^Milsive loading, that is, with an infinitesimal 

 value of the duration ©, we have 



VcCt). 



. It , t>.al 



(32) 



where 



In figures 5 a»i 6 are shown diaphragm profiles for various times, 



-t/e 



i.e.^z/Pjjj© vs. r/R for various values of t, calculated with p^ = p^e , 

 and with R^ = 1,675 in., O" = 50,000 p.s.i., a^ = 0.078 in., /> « 7.8 gm./cm.^, 

 which correspond to the standard UERL diaphragm gauge. In figure 5, © = 0.1 

 msec. , corresponding to rather impulsive loading, and in figure 6, 6 = 1 msec, ^ 

 corresponding to much longer duration. It is apparent that the diaphragn bends 

 much more sharply at the e dge of the flat central portion in figure 5 than in 

 figure 6. 



54 



