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

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JV<br />

Strength- reserve is the ratio <strong>of</strong> the strez.gth limit <strong>of</strong> the<br />

material to the maximum stress rising in the material <strong>of</strong> a part<br />

iWhen it is in Operation:<br />

• i• • __ a. •(1.10)<br />

Plasticity 'reserve can be determined from formula<br />

'<br />

[ O,. OMSX' or Pmax<br />

(10.2)<br />

if the stresses are expressed in loads. This calculation is called<br />

the limiting load calculation.<br />

Sn > I; no2 >i<br />

<strong>The</strong> conditions for the operating capability <strong>of</strong> a part abe<br />

As seen from the formulas, a substantial factor determining<br />

strength reserve is the quality <strong>of</strong> the. material. Obviously, the -higher<br />

G06, the higher the strength reserve will be <strong>and</strong> the easier, all<br />

other things being equal, it will be 'o make a part or structural<br />

element from 'it with the required properties.<br />

What re4uirement<br />

should be ,imposed ;on materials to ensure<br />

, high stuctura'l strength reserve with the least weight? <strong>The</strong> following<br />

requir;ements are imposed on structural matiirials used in extraterrestrial<br />

,electrical rocket engines <strong>and</strong>, particular, in reactor units:<br />

-high<br />

strength (strength limit must be the highest possible);<br />

- high-temperature strengths.<br />

- oxidation, resistance - high resistance to interaction with<br />

sir <strong>and</strong> other gases at high temperatures;<br />

- good weidability;<br />

- small cross sections for capture (absorption) (<strong>of</strong> •neutrons;<br />

55

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