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

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

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It is perfectly obvious that the element is in a threedimensional<br />

stressed state. <strong>The</strong> following dependences are valid:<br />

I<br />

I<br />

B<br />

We examined the strains <strong>of</strong> the element er <strong>and</strong> q•: its elongation<br />

<strong>and</strong> the radial displacement <strong>of</strong> all points <strong>of</strong> its cross sections.<br />

<strong>The</strong> radial displacement <strong>of</strong> points <strong>of</strong> the inner surface <strong>of</strong> the element<br />

is designated by u. <strong>The</strong> points <strong>of</strong> the outer surface are displaced<br />

along the radius u + du; thus, the thickness <strong>of</strong> this element<br />

increases by du <strong>and</strong> the relative elongation <strong>of</strong> the material in a<br />

radial direction.<br />

d + du - dr du<br />

dr dr<br />

In<br />

elongation is<br />

the direction <strong>of</strong> peripheral stresses a the relative<br />

a l b,--ab (r+u)d --r? u..<br />

ab<br />

r<br />

hence<br />

I<br />

E<br />

U9<br />

r<br />

198

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