3D measurement of field-induced deformations in magnetic hybrid materials

本提案最后一个资助期的目的是测量接近真实系统的磁性混合材料的内部变形。这些信息将被用来对这类材料有充分的了解。使用的方法是前两个建国时期使用的方法的延续和进一步发展。利用光学显微镜技术(透射式和共聚焦显微镜)，我们确定了磁性粒子和示踪剂粒子在材料中的轨迹。这将使我们能够推导出变形场和其他内部数据。具体地说，我们打算1.精确地表征磁性粒子之间的基质中介相互作用。这里的目标不仅是相互作用本身，而且是可以用共焦显微镜确定的潜在变形场。2.使用这种相互作用，在材料中引起大变形。这将使用周期性结构的系统来实现，这些系统允许集体效应，从而使系统对激励做出更大的响应。3.测量在外加磁场影响下几个磁性颗粒之间的变形场。在这里，我们特别着眼于不同长度尺度的比较，例如与Odenbach小组合作。4.研究了有限频率的磁激励对系统性能的影响。作为磁性杂化材料基质材料的材料大多是粘弹性的。这是一个强烈的暗示，磁力效应依赖于频率。我们打算调查这些影响。5.确定磁性凝胶中材料失效的具体模式。磁性杂化材料中磁性粒子的位移导致局部非常强烈的变形。这些强烈的变形是否会导致材料在反复加载下失效？6.分析自由或刚性边界对内部机制的影响。不仅磁性杂化材料内部的颗粒会相互影响，而且附近的表面也会改变内部的动力学。本提案中的所有工作方案都不能单独处理。所有工作包都与这项提案相关联，更重要的是，与其他项目相关联。

The aim of the last funding period of this proposal is to measure the internal deformation in magnetic hybrid materials for systems that are close to real world systems. This information will be used to obtain a well-founded understanding of this class of materials. The methods used are a continuation and further development of those used in the first two founding periods. Using optical microscopy techniques (transmission and confocal microscopy), we determine the trajectories of magnetic particles and tracer particles in the material. This will allow us to deduce the deformation fields and other internal data. Specifically, we intend to 1. characterize precisely the matrix-mediated interaction between magnetic particles. Here the goal is not only the interaction itself, but also the underlying deformation field that can be determined with confocal microscopy. 2. use this interaction, to induce large deformations in the material. This will be done with periodically structured systems that allow for collective effects which enable a larger response of the system to an excitation. 3. measure the deformation field between a few magnetic particles under the influence of an applied magnetic field. Here, we especially aim at a comparison of different length scales, e.g., in collaboration with the Odenbach group. 4. investigate the influence of finite frequencies of the magnetic excitation. Most materials used as matrix materials of magnetic hybrid materials are viscoelastic. This is a strong hint that the magneto-mechanical effects depend on frequency. We intend to investigate these effects. 5. determine specific modes of material failure in magnetic gels. The displacement of magnetic particles in the magnetic hybrid material leads locally to very strong deformations. Do these strong deformations lead to a failure of the material under repeated loading? 6. analyse the influence of free or rigid boundaries on the internal mechanisms. Not only particles in the interior of the magnetic hybrid material influence each other, also surfaces nearby will change the internal dynamics. None of the work packages in this proposal can be dealt with separately. All work packages are connected within this proposal and, more importantly, to other projects.