Magnetorheological tunable auxetic structure for energy harvester mounting

This paper presents a numerical analysis of a tunable sandwich structure with an auxetic and non-auxetic core filled with magnetorheological fluid. The proposed composite structure is intended for adaptive mounting systems used in vibration energy harvesting applications. The influence of the magnetic flux density and cellular core geometry on the static and dynamic properties of the structure was investigated using the finite element method implemented in COMSOL Multiphysics. The analysed structures were based on rotating geometries capable of exhibiting auxetic behaviour depending on geometric parameters. The magnetorheological fluid properties were modelled as a function of magnetic flux density, enabling active control of the effective stiffness of the composite. Numerical simulations included static analysis, eigenfrequency analysis, and frequency response analysis for magnetic flux densities ranging from 0.05 to 1 [T]. The obtained results demonstrated that increasing the magnetic flux density significantly modifies the dynamic response of the structure. The auxetic core exhibited higher stiffness sensitivity to magnetic field variations compared to the classical non-auxetic structure. The proposed concept enables adaptive tuning of structural dynamic properties and may improve the operational efficiency of vibration energy harvesters operating under variable excitation frequencies.