Homogenization-Based Constitutive Models for Magnetorheological Elastomers at Finite Strain

有限应变磁流变弹性体基于均质化的本构模型

• 批准号: 0708271
• 负责人: Pedro Ponte Castaneda
• 金额: --
• 依托单位: University of Pennsylvania
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-15 至 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0708271&HistoricalAwards=false
• 关键词: Homogenization; Based; Constitutive; Models; Magnetorheological

Ponte Castaneda0708271 Magnetorheological elastomers (MREs) are multi-phase,multi-functional material systems consisting of magnetically"hard" or "soft" particles embedded in an elastomeric matrixphase. Because of the magnetic interactions between theparticles, these materials are magnetostrictive and theirmechanical response can be modified smoothly and reversibly inreal time. Conversely, the presence of strain in these materialscan be detected by induced changes in the overall magnetization. Although "macroscopic" (continuum mechanics) approaches for MREshave been in existence since the 1950s, more "microscopic"theories with truly predictive capabilities are much more recentand so far have been restricted to the linear (infinitesimalstrain) regime. The investigator develops nonlinearhomogenization techniques and applies them to generateconstitutive models for magnetorheological elastomers that arevalid in the finite-strain regime. This builds on earlier work bythe investigator for reinforced elastomers and uses extensions ofvariational "linear comparison" homogenization techniques thathave been developed previously. At the theoretical level, themodels account for: (i) the strongly nonlinear response of theconstituents, including nonlinear ferrolectric behavior for theparticles, as well as nonlinear mechanical response for theelastomeric matrix, (ii) microstructural information, such asparticle shape and orientation, as well as their spatial andorientational distribution, (iii) coupled magnetoelasticconstitutive behavior, and (iv) finite deformations. At theapplications level, the methodology is used to optimally selectthe constituent properties (e.g., magnetically hard vs. softparticles, magnetically isotropic vs. anisotropic particles) andthe microstructural variables (e.g., particle shape andconcentration, aligned distribution of orientations vs. randomorientations, etc.) to enhance the magnetostrictive and sensingcapabilities of these materials. Magnetorheological elastomers (MREs) are composite materialswith "smart" or "intelligent" properties. As a consequence ofthese special properties, MREs hold great promise for use assensors and actuators in many industrial applications, includingthe automotive, electronics, and robotic industries. In addition,they are lightweight, inexpensive and easily processed into amyriad of shapes. However, in order to achieve their fullpotential, a better mathematical understanding is necessary oftheir complex -- highly coupled and nonlinear -- macroscopicbehavior, especially in the large-deformation regime. To aid inthis process, the investigator develops a homogenization-basedapproach to accurately model the macroscopic behavior of MREs,incorporating the dependence on the magnetic properties of theparticles, their initial distribution and orientation(microstructure), as well as the evolution of this microstructureunder large deformation. Finally, because of their actuationproperties MREs provide an artificial analogue of human muscle,and the project has implications for other types of smartmaterials, including electroactive polymers (EAPs), which couldfind applications in biotechnology and other areas of Federalstrategic interest.

Ponte Castaneda0708271 磁流变弹性体 (MRE) 是多相、多功能材料系统，由嵌入弹性体基体相中的磁性“硬”或“软”颗粒组成。 由于颗粒之间的磁性相互作用，这些材料具有磁致伸缩性，并且它们的机械响应可以实时平滑且可逆地修改。 相反，这些材料中应变的存在可以通过整体磁化强度的感应变化来检测。尽管 MRE 的“宏观”（连续介质力学）方法自 20 世纪 50 年代以来就已经存在，但具有真正预测能力的更多“微观”理论是最近才出现的，并且迄今为止仅限于线性（无穷小应变）体系。 研究人员开发了非线性均质化技术，并将其应用于生成在有限应变范围内有效的磁流变弹性体的本构模型。 这是建立在研究者早期针对增强弹性体的工作的基础上的，并使用了先前开发的变分“线性比较”均质化技术的扩展。 在理论层面上，该模型考虑了：(i) 成分的强非线性响应，包括颗粒的非线性铁电行为以及弹性体基体的非线性机械响应，(ii) 微观结构信息，例如颗粒形状和方向，以及作为它们的空间和方向分布，（iii）耦合磁弹性本构行为，以及（iv）有限变形。 在应用层面，该方法用于优化选择成分特性（例如，硬磁颗粒与软颗粒、磁各向同性颗粒与各向异性颗粒）和微观结构变量（例如颗粒形状和浓度、取向的对齐分布与随机取向等）。增强这些材料的磁致伸缩和传感能力。 磁流变弹性体（MRE）是具有“智能”或“智能”特性的复合材料。 由于这些特殊特性，MRE 在许多工业应用中作为传感器和执行器具有广阔的应用前景，包括汽车、电子和机器人行业。 此外，它们重量轻、价格便宜且易于加工成各种形状。 然而，为了充分发挥它们的潜力，需要对它们复杂的高度耦合和非线性的宏观行为有更好的数学理解，特别是在大变形状态下。 为了帮助这一过程，研究人员开发了一种基于均质化的方法来准确模拟 MRE 的宏观行为，其中纳入了对颗粒磁性、初始分布和方向（微观结构）以及大变形下微观结构演变的依赖。 。 最后，由于 MRE 的驱动特性，MRE 提供了人类肌肉的人工类似物，并且该项目对其他类型的智能材料具有影响，包括电活性聚合物 (EAP)，它可以在生物技术和联邦战略利益的其他领域找到应用。