Numerical Simulations in Non-Monotone
Elastodynamics Involving Young-Measure Approximations

C. Carstensen
Institute for Applied Mathematics and Numerical Analysis
Vienna University of Technology
Wiedner Hauptstrasse 8-10/115
A-1040 Wien, Austria
Carsten.Carstensen@tuwien.ac.at

and

Marc O. Rieger
Department of Mathematical Sciences
Carnegie Mellon University
Pittsburgh, PA 15213
rieger@sns.it

Abstract: Microstructures in phhase-transitions of alloys can be modeled by the energy minimization of a non-convex energy density $\phi$. Their time-evolution leads to a nonlinear wave equation $u_{tt} = {\rm div}\ S(Du)$ with the non-monotone stress functions $S=D\phi$ and proper bo undary and initial conditions. This hyperbolis initial-boundary value problem is expected to allow, in general, solely Young measure solutions. This paper introduces a fully-numerical time-space discretization of this equation in a corresponding very weak sense. It can be shown that discrete soluutions exist and generate weakly convergent subsequences whose limit is a Young measure solution. Numerical examples in one space dimension illustrate the time-evolving microstructure of a nonlinearly vibrating string.

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