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A Solution to the Inherent List on Nimitz Class Aircraft Carriers

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Stress Calculati<strong>on</strong>s:<br />

k = coefficient that depends <strong>on</strong> <str<strong>on</strong>g>the</str<strong>on</strong>g> plate edge c<strong>on</strong>diti<strong>on</strong>s,<br />

aspect ratio (AR) of <str<strong>on</strong>g>the</str<strong>on</strong>g> panel, and positi<strong>on</strong> of point being c<strong>on</strong>sidered<br />

a := kP- -<br />

p = pressure based <strong>on</strong> limiting ballast add for shell plating calculati<strong>on</strong>s<br />

'^imply_supported •<br />

a := 114in b :- 15-in<br />

lb<br />

P ^ 16.81- t := .3125n<br />

. 2<br />

in<br />

lb<br />

"max allowable= 40,000-<br />

m<br />

b = panel width<br />

a = panel length<br />

t = plate thickness<br />

^simply_supported ■ 'Simply_supported<br />

Ic , j •= 5 k values are most c<strong>on</strong>servative<br />

*t;lamped •<br />

based <strong>on</strong> 15 in separati<strong>on</strong> between stiffeners<br />

I AW with <str<strong>on</strong>g>the</str<strong>on</strong>g> General Specs (Secti<strong>on</strong> 100)<br />

I ^<br />

>2<br />

Jb_<br />

simply_supported 29048-<br />

. 2<br />

in<br />

'clamped • Clamped<br />

I ^<br />

'clamped<br />

Jb_<br />

19365-<br />

. 2<br />

m<br />

Maximum Allowable Stress for HTS is 40,000 psi. By adding stiffeners at 15 in, this stress falls below that of simply supported<br />

and that of clamped. Simply supported and clamped structural cases are idealizati<strong>on</strong>s of structural member support illustrating<br />

zero stiffness and infinite stiffness, nei<str<strong>on</strong>g>the</str<strong>on</strong>g>r of which exists in any real-world structural system. On board ship, structural systems<br />

can be c<strong>on</strong>veniently approximated by <strong>on</strong>e or <str<strong>on</strong>g>the</str<strong>on</strong>g> o<str<strong>on</strong>g>the</str<strong>on</strong>g>r case, but in fact have stiffness between <strong>on</strong>e or <str<strong>on</strong>g>the</str<strong>on</strong>g> o<str<strong>on</strong>g>the</str<strong>on</strong>g>r. Navy structural<br />

analysis is based off clamped ends, <str<strong>on</strong>g>the</str<strong>on</strong>g>refore <str<strong>on</strong>g>the</str<strong>on</strong>g> stress falls well below maximum allowable.<br />

clamped ^«a, "max_allowabl<<br />

147

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