LOADS ACTING ON A SHIP AND THE ELASTIC RESPONSE OF A SHIP 



287 



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-3.30 PM 



10 Sec- 



tW 



■20Sec 



-30Sec- 



%0^'^^ ^^'^vJ^^^^'^^ 



40Sec- 



50 Sec - 



864 Ibper sq. in Steel Stress 



±r 



T" 



-3.31 PM 



Strain Record on S.S.Westboro at Time oi Slamming 

 Fig. 37 Strain record on SS Westboro at time of slamming (from Adm. Ship Weld. Comm. Rep. No. 8, 195}) 



Pressure Gages 

 Gage Location 



1 3in.Fwdof Fr 2I,8'/4in.Stbdof(|. 



2 3in Fwdof Fr23,8'^in.S+bdof t 



3 T^^in. Aftot Fr23,8''4ln.Porto-f t 



4 l^'gin.Aftot Fr23,8'iiin. Stbdot <t 



5 75-gm.Attot Fr ■a3,3in.Stbd ot Gin. Longitudinal 



6 7^-^ in. Aft of FrZ3,3in. Stbd of Longitudinal! 



7 3in.Aftof Fr24,8''4 in. Stbdof <t 



8 l|3.'4 in.Af+of Fr 28, S'li in.Stbd of <t 



9 5G Accelerometer 2 in. Fwd of Fr 24 on 4. l^eel 



Strain Gages 



Goqe Location 



... , * 



A Longitudinal Tensile Strain, Center of Panel Fr 22-23, 8^ m. Stbd t 



B Longitudinal Bending Strains, Center of Panel fr 22-23, S'^j in. Stbd <t 



C Longitudinal Tensile Strain, 15.9 in. Aft Fr 23, 8'ivin.Stbd <t 



D Longitudinal Bending Strain, 15.9 in. Aft Fr 23, 8V^ in. Stbd 4. 



E Longitudinal Tensile Strain, 22.1 in. Aff Fr 23, 8'^ in. Stbd <t 



F Longitudinal Bending Strain, 22. 1 in. Aft Fr 23, B''4 in. Stbd <t 



G Longitudinal Hull Strain 15 in. Aft Fr 23 on t Keel 



I Deflection 6age on Center of Test Panel 



Fig. 38 Location of gages and shell expansion on USCGC Unimak (from Greenspon, Jasper, and Birmingham, 1957) 



This may also be the case, with fast cruisers, aircraft 

 carriers and even fast passenger liners.-" 



Ill the process outhned in the foregoing the bottom 

 impact plays only a secondary part and the bow emersion 

 is therefore not a necessary prerequisite to the f)ccurrence 

 of a slam. This is illustrated by Tattle 9 taken from 

 Warnsinck and St. Denis (3-1957, NSxMB Symp.). In 

 two most severe slams, in which the beii,ding moment 

 amid.'^hips was approximately doubled, there was no bow 

 emersion. 



" See Jasper and Hiriniii)j;hara (13-1958). 



In addition to the .severe shocks recorded as slams, 

 the freciuent bow immersion in the head seas causes 

 shocks of sufficient magnitude to maintain the hull in a 

 continuous state of vibration. This was noted in model 

 tests by Sato and by Lewis and Dalzell. 



The effect of slamming shocks on the bending moments 

 will be discussed in Section 5.5. 



5.4 Water Pressures in Slamming. Theories of 

 Wagner and their adaptation to ships by Szebehely and 

 M. A. Todd, model tests, and sea observations outlined 

 in previous sections, taken together, form qualitatively 



