【作者】 高伟；

【导师】 王省哲；

【作者基本信息】 兰州大学 ， 固体力学， 2014， 硕士

【摘要】 铁磁颗粒夹杂弹性体是由磁性颗粒与橡胶类软材料组成,具有磁场可控的剪切特性、阻尼特性等,并可以在外场激励下产生大应变、复杂变形、迅速响应等诸多优点。其在减振降噪、智能材料与智能驱动等领域有着广泛的应用前景,是近些年新兴的一类磁性智能复合软材料。本文以描述铁磁颗粒夹杂弹性体的力学行为与建立磁致特性的预测模型为出发点,分别对铁磁颗粒随机分布的各向同性弹性体与具有倾斜链结构的铁磁复合材料进行了研究与分析。首先利用磁特性优异的羰基铁粉与室温环境中可硫化的硅橡胶,制备出不同体积分数颗粒随机夹杂的铁磁复合材料。通过光学显微镜与扫描电子显微镜对微观结构进行观测与分析,表明颗粒在基体内具有一定稳定性与均匀分散性,制备的材料整体性能良好；利用实验室力-磁-热耦合测试系统对其进行拉伸力学性能测试,探究了铁磁颗粒含量以及外加磁场对材料宏观力学性能的影响,实验测量了不同铁磁性颗粒夹杂体积分数下的应力应变曲线,外加磁场下的磁致力学性能增强效应等；以及借助于有限元ABAQUS软件对相关实验测试结果进行了数值拟合。结果表明：磁性颗粒夹杂复合材料的拉伸力学行为依然表现出与单纯基体软材料类似的超弹性特性,并获得了描述其力学行为的修正Mooney-Rivlin超弹性模型参数,较好地预测了其超弹性力磁行为的应力应变关系。其次,考虑具有链状结构排布的磁性颗粒夹杂复合材料,基于磁偶极子理论建立了具有倾斜链结构的铁磁颗粒夹杂弹性体理论模型,给出了不同链内间距与链间距比、以及不同外加磁场与倾斜角下磁致模量的变化关系与规律。该模型不仅能够较好解释相关实验结果,还可以为制备与设计具有特殊性能的颗粒夹杂材料提供一定的理论指导。更多还原

【Abstract】 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.更多还原