561 



by an exponential wave with a peak pressure -p^ and time constant 9 

 (Eqiiation 28). The quantity Zq (0*,t) is obtained by replacing by 9* 

 in Equation 33. With an exponential wave, (Equation 28) the deflection 

 at time t of an unbaffled diaphragm mounted in a fixed frame is l/2 Zq 

 (9, t). - 



The time of deflection tjjj is equal to the lowest positive value of t 

 satisfying 



az„ (t) 



o 



= iSh) 



I 



dt 



Correspondingly the raajciraum deflection Zjj is Z^ (t^) . 



The standard UEKL steel diaphragm has the following specifications: 



Radius R = 1.64 in. 

 o 



Thickness a^ = O.O78 in. 

 Yield stress (T^ = 60,000 lbs/in^ 

 Density /* = 7.8 gm/cm^ 

 For such a diaphragm we have: 



0, = 10.i<- microsec 

 u>o = 6.1A(millisec)"-'- 



X = 2.75 



If this diaphragm is mounted in sua. infinite free baffle having an average 

 thickness of 1 in. and a density of f .& gm/cm', 



= 66.7 microsec 



An 81^-0 gm. charge of TNT (density 1.59) placed at a distance of 

 k8 in. produces a shock wave which can be approximated by an exponential 

 wave in which p = 6200 lbs/in^ and 9 =: 112 microsec. 



This wave should theoretically produce the following deflections 

 under the conditions indicated: 



Description of Baffle Mi"-) t^ (microsec.) 



