134 



47 



0.1 



0.2 



0.3 



0.4 



0.5 



0.6 



Proportionate Deflection 



Figure 38 - Pressure-Deflection Curves for Two Copper Plates 



! = 2.56 inches )i = 0.016 inch a„ = 39,625 pounds per square inch 



In Figures 38, 39. ^0. 4^. af^d 42, p' has been plotted against z/a 

 for different specimens of each of the five materials used. Figure 1^3 shows, 

 for each of the five metals, average values of p' plotted against z/a. In 

 this and the following figures the plots extend only over the range of the 

 weakest specimens. Thus the highest values for furniture steel are excluded. 



The energy W required to deform the diaphragms was estimated from 

 the pressures deforming the diaphragms and the change in the volume V en- 

 closed between the deformed diaphragm and its initial plane. The measure- 

 ments indicated that the distended diaphragms closely approximated spherical 

 caps in configuration. Therefore, with good accuracy, by Equation [15] 



and 



dV = Y 7i-(a^ + 2^)dz 



Accordingly, the change In volume was estimated from the central deflection, 

 and the energy 'W= fpdV calculated by numerical integration. Figure U'l shows 

 for each of the five metals, average values of W' plotted against z/a. As in 

 Figure U3 the curves fall closely together. 



