Magnetoelectric and magnetomechanical interactions in compliant composite materials

该项目的拟议继续是基于2018-2020年当前阶段的初步结果。的主要目标是设计，制造和表征符合磁电（ME）层状结构，包括磁致伸缩弹性体（MAE）作为磁致伸缩相和柔性聚合物作为压电相。压电聚合物将是商业聚偏二氟乙烯或基于聚二甲基硅氧烷的微结构铁电材料。这种复合材料中的直接ME效应源于本构材料中磁致伸缩和压电之间的应变介导耦合。在这方面，实验研究的变形MAE机构在均匀磁场中是重要的。现有的理论还没有达到的状态，在那里可以提供制造指南，以设计一个MAE试样与所需的磁变形。目前，关于MAE磁致伸缩的实验结果比较零散，大多是参考前几代MAE的结果，而且常常相互矛盾。正在进行的项目中的软MAE的开发已经导致了磁致拉伸应变的演示，这可以被认为是一个记录。将对均匀磁场中宏观MAE体（例如圆柱体和球体）的变形进行系统研究，以获得对样品形状（纵横比）、材料成分和微粒内部结构排列的依赖性。从这些实验中，可以推导出压磁系数和最近预测的大规模变形（形状变形）的球形MAE样品应观察。 在目前的项目中，发现了MAE管的大威德曼扭曲。这种影响应进一步研究。将测量Wiedemann扭曲对微粒几何参数、材料组成和内部结构排列的依赖性。获得的数据集的线性和旋转变形的MAE机构将用于与现有的和未来的理论模型进行比较。所获得的结果的可能应用是磁控线性和扭转致动器、磁场传感器、能量收集装置等。

The proposed continuation of the project is based on the preliminary results originating from the current stage 2018-2020. The primary goal is to design, fabricate and characterize compliant magnetoelectric (ME) layered structures comprising a magnetoactive elastomer (MAE) as the magnetostrictive phase and a flexible polymer as the piezolectric phase. The piezoelectric polymer will be either a commercial polyvinylidene fluoride or a polydimethylsiloxane-based microstructured ferroelectric material. The direct ME effect in such composite materials originates from the strain-mediated coupling between magnetostriction and piezoelectricity in constitutive materials. In this context, experimental investigations of deformation of MAE bodies in uniform magnetic fields are of importance. Available theories did not reach the state yet, where fabrication guidelines can be provided in order to design a MAE specimen with the desired magnetodeformation. Hitherto, experimental results on MAE magnetostriction are rather fragmentary, mostly refer to earlier generations of MAEs and are often contradicting. The development of soft MAEs in the running project already led to demonstration of a magnetically induced extensional strain, which can be considered as a record. Systematic investigations of deformations of macroscopic MAE bodies (e.g. cylinders and spheroids) in uniform magnetic fields will be performed in order to obtain the dependences on the sample shape (aspect ratio), material composition and the internal structural arrangement of microparticles. From these experiments, the piezomagnetic coefficient can be derived and the recently predicted large scale deformation (shape morphing) of spherical MAE samples should be observed. In the current project the large Wiedemann twist of a MAE tube was discovered. This effect should be investigated further. The dependences of the Wiedemann twist on the geometrical parameters, material composition and the internal structural arrangement of microparticles will be measured. Obtained data sets for linear and rotational deformations of MAE bodies will be used for comparison with the existing and future theoretical models. Possible applications of obtained results are magnetically controlled linear and torsional actuators, magnetic field sensors, energy harvesting devices etc.