FE-Analysis of the Demagnetization Effect and Stress Inhomogeneities in MSMA Samples

Krishnendu Haldar (1) , Bjoern Kiefer (2) , Dimitris Lagoudas (3)

1 TAMU - Department of Aerospace Engineering [College Station]
2 Department of Mechanical Engineering
3 Texas A&M University [College Station]

This paper is concerned with the finite element analysis of boundary value problems involving nonlinear magnetic shape memory behavior, as might be encountered in experimental testing or engineering applications of MSMAs. The presented investigations mainly focus on two aspects: First, nonlinear magnetostatic analysis, in which the nonlinear magnetic properties of the MSMA are predicted by the phenomenological model previously developed by Kiefer and Lagoudas, is utilized to investigate the demagnetization effect on the interpretation of experimental measurements. An iterative procedure is proposed to deduce the true constitutive behavior of MSMAs from experimental data that typically reflect shape-dependent system response. Secondly, the common assumption of homogeneous Cauchy stress distribution in the MSMA sample is tested. This is motivated by the expectation that the influence of magnetic body forces and body couples caused by field matter interactions may not be negligible in MSMAs that exhibit blocking stresses of well below 10 MPa. To this end, Maxwell stress distributions are first computed in a post-processing step, based on the magnetic field and magnetization distributions obtained in the magnetostatic analysis. Since the computed Maxwell stress fields, though allowing a first estimation of the magnetic force and couple influence, do not satisfy equilibrium conditions, a finite element analysis of the coupled field equations is performed in a second step to complete the study. It is found that highly non-uniform Cauchy stress distributions result under the influence of magnetic body forces and couples, with magnitudes of the stress components comparable to externally applied stress levels.

Mots clés: Physical Sciences

Domaines: Matière Condensée [cond-mat]

Krishnendu Haldar, Bjoern Kiefer, Dimitris Lagoudas. FE-Analysis of the Demagnetization Effect and Stress Inhomogeneities in MSMA Samples. Philosophical Magazine, 2011, pp.1. ⟨10.1080/14786435.2011.602031⟩. ⟨hal-00725401⟩