371 



The comparisons are made for the UERL gauge using a thin steel 

 diaphragm whose specifications are as follows: 



Radius, R^ - 1,65 in. 



Thickness, aQ - 0.085 in.* 



Yield Stress, <r^ - 60,000 p.s,i.7' 



Density, fi - 7.8 gm, cm, -^ 

 The diaphragn is mounted on a steel block such that it is backed by air. The 

 mounting block weighs about 25 lbs, and is fastened to a large steel ring. 

 The face of the block extends only a small distance beyond the edge of the 

 diaphragm; consequently the calculations are made on the assumption of a 

 small baffle. 



In Table I we compare the calculated and experimental-' values of 

 the maximum central deflection z^of the diaphragm after attack by a shock 

 wave from Mark 6 depth charges at a distance R . The charges were loaded 

 with a wei^tW of cast TNT whose density lies between 1.55 and 1.60 gra. cm. -^. 

 Three sets of calculated values are given: (1) calculated from the twonnode 

 Bessel-function treatment using theoretical pressure-time curves;-' (2) cal- 

 culated from the two-mode Bessel^unction t reatment using the following empir- 

 ical pressure-time curves;«i/ 



'••^ ( ^ \- I.IA 



Pm = 20,400 [^ 



® = 0-073; (;^J 



* In the experiments considered "Lot III" plates were used with values of the 

 thickness scattered closely about the value given above. The experimental 

 values of the maximum deflection are corrected for the deviations of the 

 thickness from the value of 0.085 in, 



/ Value quoted by the supplier. 



1/ OSRD Report UE-13, p. 10; OSRD Report UE-U, p. 10. 



2/ OSRD Report 2022 (1943). 



2/ OSRD Repo. o UE-16, p. 9. 



56 



