RUI: Magneto-Mechanical Coupling in Isotropic vs. Anisotropic, Hard- vs. Soft- Magnetic Magnetorheological Elastomers

磁流变弹性体（MREs）是由橡胶（弹性体）和磁性颗粒制成的复合材料，其机械行为（流变学）在磁场中发生变化。MRE行为理论将这种变化归因于粒子内部产生的磁力矩。然而，这项工作解决了由软磁颗粒（如铁）形成的mre（不产生内部转矩）和由硬磁颗粒（如永磁体）形成的mre（产生磁转矩）之间行为的根本差异。本工作的目的是研究不同材料成分的有效模量在剪切和压缩、磁化诱发应变（或磁致伸缩）和微观结构。有效模量将通过测量材料来确定？S振动响应。磁致伸缩将用光学显微镜测量。并利用x射线断层扫描对其微观结构进行表征。最后，材料做功的能力将通过确定可产生的力的大小来测量。磁流变流体在技术上很重要，因为在其使用寿命内，磁流变流体的性能比其最接近的竞争对手要好。这项研究是重要的，因为软磁和硬磁粒子之间的根本区别导致了一些可能被利用的磁-力学对称性的定义。例如，作者发现使用硬磁粒子的磁磁共振可以作为可逆致动器，而使用软磁粒子的磁磁共振则不能。这项工作将通过Rowan？工程诊所和物理研究课程。本课题将用于材料科学、计算材料科学和（高级）固体力学课程。K-12学生参加材料科学暑期学院，R.U.M.E./C.H.A.M.P.星期六学院和EOF/MAP大学预科学院也将参与这项研究。

Magnetorheological elastomers (MREs) are composite materials, made from rubber (?elastomers?) and magnetic particles, whose mechanical behavior (?rheology?) changes in a magnetic field. Theories on MRE behavior assign this change to magnetic torques developed within the particles. This work, however, addresses the fundamental difference in behavior between MREs formed from soft-magnetic particles like iron, which do not develop internal torques, and those formed with hard-magnetic particles (e.g. permanent magnets) that do generate magnetic torques. The objectives of this work are to study the effective modulii in shear and compression, magnetization induced strain (or magnetostriction), and microstructure of different material compositions. Effective modulii will be determined by measuring the material?s response to vibration. Magnetostriction will be measured using optical microscopy. And, the microstructure will be characterized using x-ray tomography. Finally, the ability of the material to perform work will be measured by determining the amount of force that can be generated.MREs are technologically important because they are expected to perform better over their working lifetimes than their closest competitors, magnetorheological fluids. This study is important because the fundamental difference between soft-magnetic and hard-magnetic particles leads to definitions of several magneto-mechanical symmetries which may be exploited. For example, the authors have found that MREs using hard-magnetic particles can serve as reversible actuators whereas MREs using soft-magnetic particles cannot. This work will engage 10+ undergraduates through Rowan?s Engineering Clinics and Physics Research courses. Topics from this project will find use in Materials Science, Computational Materials Science, and (Advanced) Solid Mechanics courses. K-12 students participating in the Summer Institute in Materials Science, R.U.M.E./C.H.A.M.P. Saturday Academy, and the EOF/MAP Precollege Institute will also be exposed to this research.