Numerical investigation of a coupling problem in magnetorheological elastometr FEM simulations

Magnetorheological elastomers contain carbonyl iron particles of diameter of several microns, each that are dispersed in the polymer resin. These particles are grouped in structures like chains. Properties of such materials can be changed by applying an external magnetic field and they can vary in a wide range. When the magnetic field intensity rises, the effective elastic module increases. The resulting modulus increase is rapid, continuous, and reversible. For a relatively high-modulus elastomer matrix such as natural rubber, the fractional modulus increase with magnetic field can exceed 50%, while it can be even larger for low-modulus host materials. Thanks to this property MREs are used in constructions like controlled vibration dampers, absorbers (TVAs), clutches, actuators, stiffness tunable mounts and suspensions, variable impedance surfaces, automotive suspension bushings, valves, brakes, safety restraint systems, semi active control systems, building vibration isolation, etc. The magneto rheological elastomers (MRE) based on carbonyl iron particles-filled polyurethane resin were investigated. Their stiffness can be changed easily by magnetic field. Such a property can be useful in construction of active vibration damping structural elements. The problem of magneto-mechanical coupling was investigated. The coupling was performed in the 2 different ways. Both of the methods were iterative. The first one was performed in the two loops: external loop was performed over forces that loaded internal rows of iron particles (dipoles) and internal where the remaining external rows of dipoles were loaded by displacement that were induced by the forces. The second method used single loop performed over magnetic forces that were applied to external rows of dipoles and were recalculated in subsequent iterations accordingly to the change of distances between rows of dipoles. Iterations were performed until the state of balance was reached. The compliance of results confirms the correctness of applied numerical methods of MRE behaviour under applied magnetic field.