The Finite Element Method for the Analysis of Non-Linear and ...
The Finite Element Method for the Analysis of Non-Linear and ...
The Finite Element Method for the Analysis of Non-Linear and ...
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<strong>The</strong>rmoelastoplasticity <strong>and</strong> Creep<br />
This behavior exhibits <strong>the</strong> time effect <strong>of</strong> increasing strains under constant<br />
loads or decreasing stress under constant de<strong>for</strong>mations (relaxation)<br />
Typical examples <strong>of</strong> such behavior are metals at high temperatures<br />
<strong>The</strong> <strong>the</strong>rmal strain(ɛ = α∆T ) <strong>and</strong> <strong>the</strong> creep strain now enter <strong>the</strong><br />
<strong>for</strong>mulation <strong>of</strong> <strong>the</strong> stress strain relationships.<br />
Creep<br />
Creep is <strong>the</strong> tendency <strong>of</strong> a solid material to slowly move or de<strong>for</strong>m<br />
permanently under constant stresses. Creep tests measure <strong>the</strong> strain<br />
response due to a constant stress. <strong>The</strong> classical creep curve represents <strong>the</strong><br />
evolution <strong>of</strong> strain as a function <strong>of</strong> time in a material subjected to uniaxial<br />
stress at a constant temperature. <strong>The</strong> creep test, <strong>for</strong> instance, is per<strong>for</strong>med<br />
by applying a constant <strong>for</strong>ce/stress <strong>and</strong> analyzing <strong>the</strong> strain response <strong>of</strong> <strong>the</strong><br />
system. In general, this curve usually shows three phases or periods <strong>of</strong><br />
behavior.<br />
Institute <strong>of</strong> Structural Engineering <strong>Method</strong> <strong>of</strong> <strong>Finite</strong> <strong>Element</strong>s II 27
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