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Our thermal stress model takes into account that the crystal behaves as an non-axisymmetric and non-isotropic thermoelastic solid.
One observes that <1,0,0> and <1,1,1> crystals exhibit strongly different shear stress patterns and levels. Since the crystal lattice are differently oriented with respect to the thermal gradient, the generated thermal stresses are different and show a 4-fold symmetry in the <1,0,0> crystal while they show a 3-fold symmetry in the <1,1,1> crystal.
In both the <1,0,0> and the <1,1,1> cases, the maximum shear stress level is located either at the crystal periphery or in the crystal core, but the <1,1,1> crystal exhibits an axisymmetric behaviour in these regions while the <1,0,0> crystal shows a non-axisymmetric shear stress level at the periphery.
Cross sections are obtained by cutting the crystal according to the plane that corresponds to the maximum value of the von Mises invariant on the crystal surface.
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| The von Mises invariant (Pa) in the crystal, in a cross section located 50 mm above the tri-junction: top, <1,0,0> crystal; bottom, <1,1,1> crystal. |
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