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Section 6: Material modelling in solid mechanics - GAMM 2012

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34 <strong>Section</strong> 6: <strong>Material</strong> <strong>modell<strong>in</strong>g</strong> <strong>in</strong> <strong>solid</strong> <strong>mechanics</strong><br />

<strong>in</strong>corporated s<strong>in</strong>ce the boundary value problem of the non-convex energy function is ill posed [2].<br />

Deal<strong>in</strong>g with multiple energy wells is numerically very challeng<strong>in</strong>g. The solution is not determ<strong>in</strong>istic<br />

as any tw<strong>in</strong> configuration can be activated from the parent configuration, which is unknown<br />

<strong>in</strong>itially. Therefore, to have a complete energy landscape <strong>in</strong> hand at the beg<strong>in</strong>n<strong>in</strong>g is impossible.<br />

The material response is <strong>in</strong>stantaneously calculated depend<strong>in</strong>g on which tw<strong>in</strong> configuration is<br />

activated. However, the m<strong>in</strong>imum stra<strong>in</strong> energy approach faces its limitation because of elastic<br />

stra<strong>in</strong> energy <strong>in</strong>variance, which occurs due to the crystallographic equivalence of possible tw<strong>in</strong><br />

configurations. Hav<strong>in</strong>g identified the preferred tw<strong>in</strong> configuration, the secondary and, hence, the<br />

multiple tw<strong>in</strong>n<strong>in</strong>g are modeled.<br />

[1] Christian J. W., Mahajan S., Deformation Tw<strong>in</strong>n<strong>in</strong>g, Prog Mat Sci, 39, 1-157 (1995)<br />

[2] Carstensen C., Ten Remarks on Non-convex M<strong>in</strong>imization for Phase Transition Simulations,<br />

Comp Meth App Mech Eng, 194, 169-193 (2005)

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