Although the cylinders were fabricated in rigid steel molds (Ref 

 2), the mold segments sprang slightly after the first disassembly. 

 After References 2 and 4 were already published, a short cylinder 

 section was mounted in a lathe to determine out-of-roundness more 

 accurately than had been done previously. The inside and outside 

 radius and the wall thickness varied by ±1/32 inch (1.6 mm). The 

 out-of-roundness parameters are summarized in Table 1 . 



Substituting Equation 2 into Equation 1 and using R = D /2 gives 

 the expression to predict implosion pressure for thick-walled cylinders: 



P. = 2 k f (t/D ) 

 im ceo 



(3) 



where 



k 

 r 



= 1.25 



- 0.12(L/D ) 

 o 



for L/D < 2 

 o 



k 



= 1.0 





for L/D ^ 2 



Equation 3 is shown in Figure 2, 

 which can be used as a design 

 chart . 



A more general design chart 

 approach is shown in Figure 3. 

 The chart is entered with a cylin- 

 to obtain the 

 The implosion pres- 

 sure can then be calculated by 

 assuming a concrete compressive 

 strength , f ' . 



The effect of different types 

 of end-closures on the implosion 

 strength was judged to be small 

 (Ref 3) so this parameter was not 

 included in the design equation. 



der L/D and t/D 

 o o 



P. /f ratio, 

 im c 



0.05 0.10 0.15 0.20 0.25 



Wall Thickness/Outside Diameter, t/D 



Figure 2. Relationship of Equation 3 for 

 thick-walled cylinders. 



