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A Solution to the Inherent List on Nimitz Class Aircraft Carriers

A Solution to the Inherent List on Nimitz Class Aircraft Carriers

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

b^2<br />

a := k-Pl — I<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 />

p = pressure based <strong>on</strong> 1000 psf <strong>on</strong> sp<strong>on</strong>s<strong>on</strong> shell plating<br />

b = panel width<br />

a = panel length<br />

t = plate thickness<br />

'Siniply_supported '■= ■'^- "^lamped •= -^ ^ ^^'"^^ ^""^ "1°^' c<strong>on</strong>servative<br />

a := 34.Sn b := 24in based <strong>on</strong> no stiffener additi<strong>on</strong><br />

P = 30.934—<br />

. 2<br />

in<br />

t := .SOn<br />

*^max_allowable~ 40,000— I AW with <str<strong>on</strong>g>the</str<strong>on</strong>g> General Specs (Secti<strong>on</strong> 100)<br />

2<br />

in<br />

^simply_supported ' *Simply_supported '^l<br />

b^2<br />

'^simply_supported ~ "o<br />

in<br />

2<br />

... b<br />

^clamped " '^clamped<br />

^clamped = 35636-^<br />

in<br />

Maximum Allowable Stress for HTS is 40,000 psi. The calcuated stresses falls between that of simply supported and that of<br />

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

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 can be<br />

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 analysis<br />

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 should be well below maximum allowable.<br />

'^clamped*^'^ ^max_allowabl(<br />

108

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