Mechanics of hard-magnetic soft materials
Mechanics of hard-magnetic soft materials
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DOI：
10.1016/j.jmps.2018.10.008
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发表时间：
2019-03-01
影响因子：
5.3
通讯作者：
Zhao, Xuanhe
中科院分区：
文献类型：
--
作者：
Zhao, Ruike;Kim, Yoonho;Zhao, Xuanhe
软材料可以通过外部刺激的远程和无线作用进行快速和大变形，提供了一系列诱人的应用，如软机器人，柔性电子产品和生物医学设备。这种材料的一个自然而简单的实施方案是将磁性颗粒嵌入软聚合物中。不幸的是，现有的磁响应软材料，如磁流变弹性体和铁凝胶，通常使用磁性软颗粒，如铁和氧化铁，其特征在于低磁性，因此缺乏保持剩余磁性的能力。因此，它们的变形仅限于简单的伸长或缩短，使得这些材料基本上不适合许多应用中所需的复杂变形。为了引入形状可编程性，已经将具有高磁性的磁性硬颗粒结合到机械软材料中。此外，最近的工作，旨在改善这种情况已经开发了制造技术和简易的路线，以工程师的快速和复杂的转换，在一个可编程的方式，通过引入复杂的图案的磁极性在软材料。所得到的结构，当适当的设计，已被证明表现出多样化和丰富的阵列的致动行为。在这项工作中，我们开发了一个合适的理论框架来分析这些所谓的硬磁软材料，以促进磁激活功能结构和设备的定量预测复杂的形状变化的基础上的合理设计。我们采用非线性场理论来描述与磁场耦合的有限变形，并认为所制造的材料的宏观行为需要一个新的本构分类的理想硬磁软材料，假设（i）材料具有剩余磁通密度，和（ii）感应磁通密度与所施加的致动磁场呈线性关系。我们实现的理论和本构关系的有限元框架，并发现显着的协议之间的模拟和实验结果的各种变形模式的硬磁软材料。使用开发的（和验证）模型，我们提出了一组说明性的例子，突出使用我们的基于模型的模拟，以指导设计的实验可实现的复杂形状变形结构的硬磁软材料。(C)2018爱思唯尔有限公司版权所有。
Soft materials that can undergo rapid and large deformation through the remote and wireless action of external stimuli offer a range of tantalizing applications such as soft robots, flexible electronics, and biomedical devices. A natural and simple embodiment of such materials is to embed magnetic particles in soft polymers. Unfortunately, existing magnetically responsive soft materials such as magnetorheological elastomers and ferrogels typically use magnetically-soft particles such as iron and iron oxides, which are characterized by the low coercivity and hence lack the capability to retain remnant magnetism. Accordingly, their deformation is limited to simple elongation or shortening, rendering these materials substantially unsuited for the complex transformations required in many applications. To introduce shape-programmability, magnetically-hard particles with high coercivity have been incorporated in mechanically soft materials. In addition, recent works aimed at ameliorating this situation have developed fabrication techniques and facile routes to engineer rapid and complex transformations in a programmable manner by introducing intricate patterns of magnetic polarities in soft materials. The resulting structures, when properly designed, have been shown to exhibit a diverse and rich array of actuation behavior. In this work, we develop a suitable theoretical framework to analyze these socalled hard-magnetic soft materials to facilitate the rational design of magnetically activated functional structures and devices based on a quantitative prediction of complex shape changes. We adopt a nonlinear field theory to describe the finite deformation coupled with magnetic fields and argue that the macroscopic behavior of the fabricated materials requires a new constitutive classification ideal hard-magnetic soft material which assumes that (i) the material has a residual magnetic flux density, and (ii) the induced magnetic flux density exhibits a linear relation with the applied actuating magnetic field. We implement the theory and constitutive law in a finite-element framework and find remarkable agreement between the simulation and experimental results on various deformation modes of hard-magnetic soft materials. Using the developed (and validated) model, we present a set of illustrative examples to highlight the use of our model-based simulation to guide the design of experimentally realizable complex shape-morphing structures based on hard-magnetic soft materials. (C) 2018 Elsevier Ltd. All rights reserved.