Von Mises yield criterion
= Von Mises yield criterion
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{title2=$\sigma':\sigma'=2k^2$}
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The <Von Mises yield criterion> depends only on the second invariant of <deviatoric stress>. With shear yield stress $k$, its surface is $\sigma':\sigma'=2k^2$; the uniaxial yield stress is $\sqrt3k$. An <associated flow rule> gives plastic strain rate proportional to $\sigma'$, up to a positive normalization of the plastic multiplier.