Voigt bound (source code)

= Voigt bound
{c}
{title2=$a^*\preceq\langle a\rangle$}

An affine trial temperature in the minimum-energy principle gives the upper tensor bound by the volume-averaged local conductivity. For an isotropic two-phase composite, $a^*\le p_1a_1+p_2a_2$. The same uniform-field variational idea supplies the familiar corresponding elastic upper bound.