467 
where fh and R ,; are constants. Eqs. &.26 are in agreement with the asymp- 
totic result of the kinetic enthalpy propagation theory Eq. 6.3. 
The most important parameters of the pressure-time curve in the 
analysis of damage to structures by explosion waves are the peak pressure, 
energy, and impulse of the wave. Since the energy is most simply related 
to our propagation theory, we shall discuss it first. The energy of the 
shock wave when it arrives at a point R is -y definition the workdone on 
the fluid exterior to the sphere R - Thus, the shock-wawe energy per unit 
area of the initial sphere of explosive is D(i)/ a? e if we denote by 
€ (R ) the shock-wave energy per gram of the initial explosive charge, we 
5) oe the , 
n 
ein) = (ya R ie (8.27) 
find 
where if e is the density of loading of the explosive. For the ses 
energy delivered to unit area, €(N) is te be divided by ‘RS W , where 
w , the weight of explosive, is to be expressed in grams / and K in 
centimeters, 
The impulse L of the shock wave has been defined by Eq. 6.10. 
We may approximate the Euler pressure-time curve of the shock wave by the 
peak approximation, -t/ fy 
p = pb. e ) (8.28) 
where the Euler time constant @ of the wave is defined as 
ye ; ad (SE). Ts (8.29) 
In terms of Lagrangian partial derivatives, the time constant is given by 
78 
