370 



V. COMPARISON OF THi:. IHEORIES OF PARTS III AND IV UITH EXPERIMENT 



The ultimate object of experimental and theoretical work on the 

 underwater damage to diaphragjna is the prediction of da-nage to ships at- 

 tacked by a given explosive iinder specified conditions. To have engineer- 

 ing significance, certain aspects of the theory must be tested by comparison 

 with e^eiriment. In this part, we compare theoretical results with experi- 

 mental results obtained at the Underwater Explosion Research Laboratory at 

 Woods Hole. 



Here we present compiarisons on the basis of both the parabolic 

 theory (Part III) and the two-mode Bessel»function theory (Part IV, SecMren 

 3) using both empiricsil and theoretical pressure-time curves for the shock 

 wave. The incompressive approximation to the water loading is used in both 

 theories and a small baffle is assumed. Consequently, for the parabolic 

 theory Eqs. (17) of Part III are used, with a factor of 1/2 multiplied into 

 the expression for r^to take account of the small (instead of infinite) 

 baffle. For the twonnode Bessel-function case the tables of Part IV, Sec- 

 tion 3 are used without modification. 



The agreement between theoretical and experimental values of the 

 maximum deflection is very good in most cases. The agreement among the 

 various sets of theoretical values themselves is satisfactory but not excel- 

 lent. The theoretical values are on the average about 15% higher than the 

 experimental values. The values calculated from the two-mode Bessel-function 

 theory are on the average about 7% higher than those from the parabolic 

 theory, the discrepancy being most conspicuous for small charge weights. 



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