Computational Study for Optimizing Microstructures and Properties of Polymer-Matrix Magnetostrictive Composite Materials

技术概述：该奖项支持复合磁致伸缩材料的理论和计算研究及教育。PI将使用相场材料建模方法来研究聚合物基磁致伸缩复合材料的性能和微观结构。这项工作可能会对磁致伸缩复合材料的加工产生影响。这项计算研究的重点是由嵌入在环氧树脂基质中的超磁致伸缩Terfenol-D颗粒组成的具有重要技术意义的复合材料。通过假定磁致伸缩复合体系的自由能，包括磁晶各向异性能、磁化壁能、长程静磁偶极子相互作用、磁偶极子与外加磁场的相互作用和磁弹性能，研究了这些体系在固化的环氧树脂中的性质。通过求解Landau-Lifshitz-Gilbert方程确定了磁化强度的时间演化。一种类似的技术被用来确定在未固化的环氧树脂中对特芬诺-D纳米颗粒进行场优化组装和控制的策略。在这种情况下，包括了短程相互作用，它解释了每个颗粒上的粘性阻力，最终为每个纳米颗粒提供了力和扭矩。了解这些材料有助于开发和应用磁性传感器、执行器和换能器的技术。聚合物粘结的Terfenol-D复合材料显著增加了电阻率，降低了涡流损耗，改善了机械韧性和拉伸强度，提供了与单块Terfenol-D合金相当的磁致伸缩应变，并扩展了工作带宽。这项研究的重点是详细了解磁致伸缩复合材料的材料性能与微观结构之间的关系，并旨在解决如何控制微观结构的问题。这项计算研究是对整体式Terfenol-D和聚合物基磁致伸缩复合材料的大量实验结果的补充，并与之密切相关，这些实验结果共同使复合材料的有效计算机辅助设计和制造成为可能。非技术总结该奖项支持对一类聚合物基复合材料的磁性进行理论和计算研究，目的是了解复合材料的结构和性能之间的关系，以及如何控制它们。聚合物基复合材料是一种重要的材料，由嵌入在环氧树脂中的磁性颗粒组成，与由相同磁性材料组成的结晶材料相比，具有许多优点。它们不太容易降解和机械故障，但仍然以与传统晶体材料相当的方式对外加磁场做出反应。这项研究对传感器和换能器技术具有潜在的影响，并将开发和分发计算工具，用于先进磁致伸缩复合材料的计算材料设计和制造。这项研究与教育活动相结合，培训未来的计算材料科学家，开发教学材料，并向该领域更大的科学家社区分发免费源代码。针对高中生和教师的外展活动也包括在这项努力中。

TECHNICAL SUMMARY:This award supports theoretical and computational research and education on composite magnetostrictive materials. The PI will use phase field materials modeling methods to study the properties and microstructure of polymer matrix magnetostrictive composites. The work may have impact on the processing of magnetostrictive composite materials. This computational research focuses on technologically important composites that are composed of giant magnetostrictive Terfenol-D particles embedded in an epoxy resin matrix. The properties of these systems, in a cured epoxy resin, are studied by assuming a free-energy of the magnetostrictive composite system that includes the magnetocrystalline anisotropy energy, the domain-wall energy, the long-range magnetostatic dipolar interactions, the interactions of the magnetic dipoles with an external magnetic field, and the magneto elastic energy. The temporal evolution of the magnetization is determined by solving the Landau-Lifshitz-Gilbert equation. A similar technique is used to determine strategies for field-optimized assembly and control of the Terfenol-D nanoparticles in the uncured epoxy resin. In this case short-range interactions, which account for viscous drag on each particle, are included which ultimately provides a force and torque on each of the nanoparticles. Understanding such materials furthers technologies aimed at the development and application of magnetic sensors, actuators, and transducers. Polymer-bonded Terfenol-D composites significantly increase the electrical resistivity, reduce eddy current loss, improve mechanical toughness and tensile strength, and provide magnetostrictive strains comparable to that of monolithic Terfenol-D alloy, and extend the operational bandwidth. A thrust of this research is a detailed understanding of the connection between materials properties of magnetostrictive composites and microstructure and aims to address how microstructure can be controlled. This computational research complements and is closely related to a large body of experimental findings in both monolithic Terfenol-D and polymer matrix magnetostrictive composites, which together enable effective computer-aided design and fabrication of the composites. NON-TECHNICAL SUMMARYThis award supports theoretical and computational research on the magnetic properties of a class of polymer-matrix composite materials with an aim to understanding the relationship between the structure of the composite and its properties, and how they can be controlled. Polymer-matrix composites are important materials, composed of magnetic particles embedded in an epoxy resin, that offer a variety of advantages over crystalline materials composed of the same magnetic material. They are less susceptible to degradation and mechanical failure but still respond to applied magnetic fields in a way that is comparable to conventional crystalline materials. This research has potential impact on sensor and transducer technologies and will also develop and distribute computational tools for computational materials design and fabrication of advanced magnetostrictive composites. The research is integrated with educational activities that train future computational materials scientists, develops instructional materials, and distributes free source codes to the larger community of scientists in this field. Outreach activities to high school students and teachers are also included in this effort.