Magnetoelastic instability induced pattern transitions in soft ferromagnetic laminates

The performance of magnetorheological elastomers (MREs) can be significantly enhanced by tailoring their microstructure. Moreover, microstructured materials when subjected to large deformations can develop elastic (reversible) instabilities; the phenomenon is often associated with dramatic microstructural transformations and can be harnessed to develop material with switchable functionalities. Here, we will present our work on instability development in soft MREs with layered microstructure, with phases exhibiting ferromagnetic behavior. To perform the magnetoelastic instability analysis, we employ the small-amplitude perturbations superimposed on finite deformations in the presence of the magnetic field. We examine the interplay between macroscopic and microscopic instabilities. We find that the layered MAEs can develop microscopic instability with antisymmetric buckling modes, in addition to the classical symmetric mode. Notably, the antisymmetric microscopic instability mode does not appear in a purely mechanical scenario (when a magnetic field is absent). Furthermore, our analysis reveals that the wavelength of buckling patterns is highly tunable by the applied magnetic field, and also by the properties and volume fractions of the phases.