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Design and Stress Analysis of Extraterrestrial ... - The Black Vault

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-KI<br />

1-<br />

SI<br />

'<br />

2I -log VJ<br />

L0<br />

Fig. 4.38. Graph for determining Fig. 4.39. Thin-wall circular<br />

critical lengths <strong>of</strong> cylindrical cylindrical shell under the effect<br />

shells,<br />

<strong>of</strong> compressive: loads.<br />

a) Critical external shearing preissure (theoretical) for a<br />

long shell (L > L ) can be determined from Bresse's formula<br />

[36):<br />

Et jS<br />

KP 4 1-r<br />

3 :'<br />

(4.19)<br />

* I<br />

where r is<br />

the radius <strong>of</strong> the shell.<br />

b) Critical comprehensive external pressdre (theoretical) for a<br />

short shell L < L can be determined from Mises' formtila [36]:<br />

I)VES 11<br />

_2L<br />

2jL2<br />

L22'<br />

2 + 12(1-IL?)r2 ( 0.t0<br />

<strong>The</strong> positive integer n is selected so that pT has the lowest<br />

value. <strong>The</strong> dpproximate value <strong>of</strong> n can be determined fror.; the<br />

graph (Fig. 4.40) or from aporouxiate formula [12]<br />

488

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