Coupled simulation of the thermo-magneto-mechanical properties of a Ni-Mn-Ga actuator

Berthold Krevet 2Manfred Kohl 1

1. Forschungszentrum Karlsruhe, IMT, Postfach 3640, Karlsruhe 76021, Germany
2. Forschungszentrum Karlsruhe (FZK), Postfach 3640, Karlsruhe D-76021, Germany

Abstract

Ferromagnetic shape memory alloys (FSMA) are a new class of materials, which show a unique combination of thermoelastic and ferromagnetic properties. In order to understand the spatially and time-resolved physical behaviour of FSMA sensors and actuators, a fully coupled model for the thermo-magneto-mechanical material properties is needed.

Micromachined Ni-Mn-Ga cantilevers have been fabricated as a test platform for evaluating physical models of the different coupling effects. A simulation tool has been developed, which couples different kinds of finite element programs for calculation of hysteretic material behaviour under multi-field loading. A two-phase shape memory model including history effects is implemented in the mechanical solver. A magnetic solver has been developed, which is capable of calculating forces and their gradients acting on temperature-dependent magnetized magnetic shape memory material.

In this paper, we present calculated static and dynamic temperature distributions of a Ni-Mn-Ga double-beam cantilever under different heating conditions taking into account the effects of martensitic phase transformation. The results are used for a self-consistent mechanical deflection analysis this actuator in the inhomogeneous magnetic field of a permanent magnet, which is determined by the spatial distribution of ferromagnetic states. The influence of the shape memory and ferromagnetic effects on the actuator performance is discussed. Dynamic simulations are performed to understand the power-dependent frequency characteristics of the actuator.

 

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Presentation: oral at E-MRS Fall Meeting 2005, Symposium C, by Berthold Krevet
See On-line Journal of E-MRS Fall Meeting 2005

Submitted: 2005-05-19 14:06
Revised:   2009-06-07 00:44