Sergio Conti, Martin Lenz, Nora Lüthen, Martin Rumpf and Barbara Zwicknagl Geometry of martensite needles in shape memory alloys 2019 https://arxiv.org/abs/1912.02274
2018
Sergio Conti, Martin Lenz, Matthäus Pawelczyk and Martin Rumpf Homogenization in magnetic-shape-memory polymer composites In Volker Schulz and Diaraf Seck, editor, Shape Optimization, Homogenization and Optimal Control, Volume 169 of International Series of Numerical Mathematics
page 1-17.
Publisher: Birkhäuser, Cham
2018 10.1007/978-3-319-90469-6_1
Sergio Conti, Benedict Geihe, Martin Lenz and Martin Rumpf A posteriori modeling error estimates in the optimization of two-scale elastic composite materials ESAIM: Mathematical Modelling and Numerical Analysis, 52: 1457-1476 2018 10.1051/m2an/2017004
2016
Sergio Conti, Martin Lenz and Martin Rumpf Hysteresis in Magnetic Shape Memory Composites: Modeling and Simulation 2016 10.1016/j.jmps.2015.12.010
Abstract: Magnetic shape memory alloys are characterized by the coupling between a structural phase transition and magnetic one. This permits to control the shape change via an external magnetic field, at least in single crystals. Composite materials with single-crystalline particles embedded in a softer matrix have been proposed as a way to overcome the blocking of the transformation at grain boundaries. We investigate hysteresis phenomena for small NiMnGa single crystals embedded in a polymer matrix for slowly varying magnetic fields. The evolution of the microstructure is studied within the rate-independent variational framework proposed by Mielke and Theil (1999). The underlying variational model incorporates linearized elasticity, micromagnetism, stray field and a dissipation term proportional to the volume swept by the phase boundary. The time discretization is based on an incremental minimization of the sum of energy and dissipation. A backtracking approach is employed to approximately ensure the global minimality condition. We illustrate and discuss the influence of the particle geometry (volume fraction, shape, arrangement) and the polymer elastic parameters on the observed hysteresis and compare with recent experimental results.