\RPv / 



'2hc! \2 

 H=3-^;^) (135) 



Galletly and Bart go into considerable discussion of various methods 

 for determining initial out- of- roundness from shape profiles. They also 

 carry out calculations for specific cylinders using Equations (132) through 

 (135), and compare their results with experimental data obtained at the 

 Model Basin. The reader is referred to Reference 44 for further details 

 of the mathematical analysis and method of numerical computation. How- 

 ever, it is worth summarizing here that the best semi-empirical method 

 for determining the "out-of- roundness" components from circularity 

 profiles is that due to Holt; this technique essentially "picks out" the 

 Fourier component corresponding to the buckling mode of the perfect 

 cylinder. For a more exact determination of the contribution due to each 

 component, a general harmonic analysis can be conducted on the most 

 complicated circularity contour, and the method of superposition can then 

 be used to determine the total "out-of-roundness" stress at any location. 

 ELASTIC GENERAL INSTABILITY OF SHELL AND RING FRAMES 



Implicit in the formulations considered so far is the premise that the 

 ring frames possess adequate bending and torsional rigidities, thus pre- 

 cluding local instability or failure of the stiffeners themselves. The in- 

 fluence of only the finite elastic properties of the ring frames on the 

 structural behavior of the shell has been included in the theories discussed 

 in the preceding sections. However, it is conceivable that if the ring 



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