5 - 



299 



!< y„ 



5 P ' , 



/^c 



k y d 

 'o 



(n) 



Energy Absorption for Piston Deflected Initially. 



unit area is 



If y^ is the maximum additional deflection above y , the energy absorbed by the piston per 



^(^m^^o'^ 





Putting 



then the ratio 



Energy absorbed by piston , i i i 



= , pcnk y (y + 2y ) (l8) 



Energy incident on piston m m o 



numerical Values, 



Piston not deflected initiall y 



Figure 1 shows the form of the deflection-time curves of the piston for the infinite plate, 

 for the finite baffle as given by equations (12) and (13) and for the infinite baffle, for the following 

 conditions typical of R.R.L. box model tests:- 



p^ = 'J.S'ixlo' 'dynes/sq-cm. 



n = 3.03x10^ secs"^ 



pc = 1.16x10 gm/sec, sq.cm. 



m = 1.31 gn/sq.cm, 



k = 8.122x10* dynes/sq. cm. /cm. 



q = 6.507x10^ sec"^ 



R^ = 21.06 cm. 



"2 = "l 



The values of p from equations (2), («) and (5) are given in Figurr 2, and the maximum 

 deflections and ratios of maximum energy absorbed to energy incident on the piston are given in 

 Table 1. 



TABLE 1. 



It is 



