Multiscale modeling of magnetosensitive materials using experimental microstructural data

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The overarching goal of the present project is the modeling and simulation of magnetoactive materials, to investigate their structure-property relationships. Special attention is paid to the modeling of magnetorheological elastomers (MREs) on multiple scales. Starting from the constitutive properties of the polymer matrix as well as the magnetic particles and accounting for the microstructural arrangement of the latter, the effective macroscopic material behavior is predicted. For both, the micro- as well as the macroscale, a continuum-based modeling approach is used. This multiscale strategy allows for a cooperation with other groups of the priority program and helps to provide an in-depth understanding of the structure-property relationships of hybrid magnetic materials. Eventually, the gained insights will help to improve the applicability of these materials in the fields of actuators and sensors.For the numerical solution of magneto-mechanical homogenization problems, simulation techniques based on the finite element method (FEM) are developed within this project. This allows for arbitrary shapes and distributions of the magnetizable particles on the microscale. Furthermore, it is possible to consider a complex nonlinear behavior of the individual constituents. Within the simulation, the local magnetic and mechanical fields are resolved explicitly, so that the generally inhomogeneous magnetization of the particles and the non-affine deformation of the polymer matrix is taken into account in the modelling approach. The related macroscopic behavior of the MREs follows from an energetically consistent scale transition process. In the first two funding periods, the principal focus was on the investigation of MREs consisting of magnetically soft particles and a purely elastic matrix. Hence, the effective behavior of such materials was free of any hystereses, i. e. completely reversible. The main objective of the third funding period is the investigation of MRE with magnetic and mechanical hysteresis effects which results from the magnetically hard behavior of the particles and the viscoelastic properties of the matrix. To this end, a detailed characterization of the magnetic and mechanical behavior of the particles and the polymer matrix is planned in cooperation with experimental working groups of the priority program. Based on the constitutive properties of the components and detailed information of the microstructure, the effective behavior of the MREs is predicted. The parameters of a macroscopic constitutive model, which describes the coupled magneto-mechanical properties of MRE, are identified by means of the predicted effective curves. Finally, it is possible to simulate the macroscopic behavior of realistic samples and components and to compare the results with experimental data.