656 



12. Tha Tensllg Strength of Water 



The value of the tensile strength for water reported here is quite at 

 variance with the value assumed by Pekeris in his description of the dome 

 velocity problem. 17) His assumption of Reynold's veJue of 5 atmospheres 

 as an upper limit is vuijustified both on the basic of this work and the 

 discussion of Temperley.5) It is difficult to see how the estimated values 

 of Table H could be in error by the order of magnitude necessary to bring 

 about correspondence with values estimated from cavitation studiesf"' for 

 example. It may be that the experimental conditions are sufficiently 

 different to account for the discrepancy. The extreme dependence of the 

 determined values of T upon the experimental method is well discussed by 

 Temperley and ovir estimates lie within the range of values reported by him 

 from various sources. 



It is interesting that the value of T estimated by this method decreases 

 as the size of the charge increases. This obseirvation would indicate that 

 the value depends upon the time constant of the shock wave or, in other 

 words, upon the length of time during which the necessary pressure is acting 

 upon the surface layer. This is reasonable and, if one is justified in 

 estimating T from dome velocity methods, this may provide a method for 

 deteiToining the energy in the shock wave as well as the peak pressure. Since 

 the time constant of a pressure wave depends not only on the size of the 

 charge but also on the distance from the center of the charge, one must on 

 this biisis assume that the apparent value of T will be larger for the higher 

 values of wV3/r for the same size of charge. There is obviously a need 

 for a great amoiint of additional work to obtain values with which to test 

 these interesting and fundamental relationships. These problsms can only 

 be indicated by the present work because the amount of data, unfortionately, 

 is not sufficient to give the solution. 



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