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D6. For different assumed shapes f(x,y) of proportional motion, the 
energy absorbed by the plate as given by equation D9 varies less for a 
given mean deflection than for a given central deflection. Thus if 
Wt) is the mean deflection 
mt) = al | Meera) evar; vlc ested ee (B20) 
The energy absorbed by the plate can be expressed in the form 
Op=# x! W(t) 
rf (Lp is equated to the incident energy(i, an estimate of wt) instead 
of w,(t) is obtained. Such estimates of Wt) vary less for different 
assumed shapes than do corresponding estimates of Wo(t). For this reason, 
results of box or drum model tests are often expressed in terms of the mean 
deflection rather than the maximum deflection. 
