Fabrication And Analysis Of Mechanical Properties Of Elastomer Filled With Ferromagnetic Particles

Elastomer filled with ferromagnetic particles is a kind of smart materials with microsized magnetizable particles dispersed in elastomers or rubber-like soft materials. It exhibits not only the significant controllable performance of electrical, magnetic, mechanical field from dipole magnetic forces between the particles in matrix, but also some advantages of large strain, various deformation modes, and quick response stimulated by an external magnetic field. The composite materials have potential applications in adaptive vibration absorbers, intelligent and smart drives, and so on. As a class of magnetic intelligent soft materials, the elastomer filled with ferromagnetic particles emerges in recent years. Based on the analysis of mechanical behaviour of the elastomer mixed with ferromagnetic particles and establishment of prediction model for magneto induced properties; the isotropic elastomers with ferromagnetic particles randomly dispersed and the anisotropic elastomers with tilted chain structure were respectively researched and discussed in this thesis.Firstly, we present the fabrication of magnetic composite materials with different volume fraction of micron-sized carbonyl iron powder which possess excellent magnetic properties and are dispered inside RTV-2silicon rubber. The inner structure of the samples were characterized by using optical microscopy and scanning electron microscope. As can be seen, the particles are distributed homogeneously and stably. In addition, the tensile mechanical properties of the specimens with/without magnetic field were tested by utilizing the mechanical-magnetic-thermal multi-field instrument in our laboratory. The effect of the volume fraction of ferromagnetic particle in mixtures and the intension of external magnetic field applied to this kind of magneto-active composites on the macroscopic mechanical properties were studied. Then, the stress-strain relationship of composites with different ferromagnetic particle proportions and the reinforcing effect under extarnal magnetic field was experimently investigated. Subsequently, the numerical simulation on the related experiment results were discussed using the commercial finite element software ABAQUS. Results showed that the mechanical behavior of composite filled with ferromagnetic particles manifest superelastic characteristic is similar to the common hyperelastic rubber-like materials. Meanwhile the parameters of Mooney-Rivlin model for describing superelastic mechanical behavior were obtained. The good predications were presented for the hyperelastic mechanical-magnetic behavior of the composite elastomer.Secondly, in view of composite materials with chain-like configuration, a theoretical model of the mixture with tilted chain structure was established based on the magnetic dipole interactions. On the basis of tilted chain-like model, we analyzed some factors including the distance between particles in the same chain and the particles in all adjacent chains, the inclination angle of particle chain and external magnetic field, which influence the magnetic modulus of elastomers. The proposed model not only explains the results qualitatively which agree well with relative experimental observations, but also provides some theoretical guidance for manufacturing and designing a particle-filled material with unique characterization by placing the particle in special microstructure.