Modeling of strongly coupled magneto-mechanical behavior in magneto-sensitive elastomers

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Field-controllable functional polymers represent a relatively new class of applied materials exhibiting a strong coupling of mechanical and external fields. The application of such fields influences the interactions between different local material phases and may cause an evolution of the microstructure. A prominent example are magneto-sensitive elastomers (MSEs) featuring mechanical moduli that become enhanced under an applied magnetic field as well as the ability for magnetically induced deformations and actuation stresses. This makes MSEs very attractive for a variety of technical implementations, especially for actoric applications such as artificial muscles, sensors, micro-robots and micro-pumps. Since the effective coupled magneto-mechanical behavior is of special interest in these applications, an in-depth understanding of the structure-property relations in MSEs as well as suitable theories for computing the effective macroscopic material response are required.MSEs represent a two-component system, in which micron-sized magnetizable particles are embedded in a soft polymer network. The flexibility of polymer sub-chains between cross-links allows a considerable degree of particle rearrangement under strong magnetic fields. As a result, the particles are prone to organize themselves into chain-like microstructures, which may considerably influence the coupled magneto-mechanical properties of MSEs. In this joint project, two work groups from the Leibniz-Institute for Polymer Research Dresden (IPF) and the Institute of Solid Mechanics of TU Dresden (IFKM) develop adapted modeling and simulation techniques to capture the hierarchical material structure, account for its evolution and predict the resulting macroscopic, strongly coupled magneto-mechanical behavior of MSEs. The theoretical predictions will be compared between both groups and with existing literature results. The modeling strategies which are pursued at IPF and IFKM will be combined to develop a unified, hybrid multiscale framework which allows for an accurate but efficient prediction of the macroscopic response of realistic MSE samples. The particular challenge is the simultaneous consideration of inhomogeneous, macroscopic magnetic and mechanical fields and their interaction with the underlying evolving microstructure. It is expected that the developement of the unified approach will benefit from the scientific exchange within the SPP that already started in the first funding period. The overall performance of the hybrid multiscale framework will be investigated by comparing simulation results for realistic MSE specimens with the experimentally observed behavior.