Modeling of strongly coupled magneto-mechanical behavior in magneto-sensitive elastomers

场可控功能聚合物是一类较新的应用材料，具有很强的机械场和外场耦合作用。这种场的应用影响不同局部材料相之间的相互作用，并可能导致微观结构的演变。一个突出的例子是磁敏弹性体（MSE），其特征在于机械模量在施加的磁场下变得增强，以及磁致变形和致动应力的能力。这使得MSE对于各种技术实现非常有吸引力，特别是对于诸如人造肌肉、传感器、微型机器人和微型泵之类的动作应用。由于有效的磁-力耦合行为在这些应用中具有特殊的意义，因此需要深入理解MSEs的结构-性能关系以及计算有效宏观材料响应的合适理论。MSEs代表一种双组分系统，其中微米级的可磁化颗粒嵌入软聚合物网络中。交联之间的聚合物子链的灵活性允许在强磁场下相当程度的颗粒重排。因此，颗粒易于组织成链状微结构，这可能会显著影响MSE的磁-机械耦合性能。在这个联合项目中，来自Leibniz-Institute for Polymer Research Dresden（IPF）和TU Dresden固体力学研究所（IFKM）的两个工作组开发了适应性建模和模拟技术，以捕获分层材料结构，解释其演变并预测由此产生的宏观，强耦合的MSEs磁-机械行为。理论预测将在两组之间进行比较并与现有文献结果进行比较。在IPF和IFKM追求的建模策略将结合起来，开发一个统一的，混合的多尺度框架，允许一个准确而有效的预测现实MSE样品的宏观响应。特别的挑战是同时考虑不均匀的，宏观的磁场和机械场及其相互作用与底层不断变化的微观结构。预计统一方法的制定将受益于在第一个供资期内已经开始的SPP内部的科学交流。的混合多尺度框架的整体性能将通过比较模拟结果与实验观察到的行为现实MSE标本。

Field-controllable functional polymers represent a relatively new class of applied materials exhibiting a strong coupling of mechanical and external fields. The application of such fields influences the interactions between different local material phases and may cause an evolution of the microstructure. A prominent example are magneto-sensitive elastomers (MSEs) featuring mechanical moduli that become enhanced under an applied magnetic field as well as the ability for magnetically induced deformations and actuation stresses. This makes MSEs very attractive for a variety of technical implementations, especially for actoric applications such as artificial muscles, sensors, micro-robots and micro-pumps. Since the effective coupled magneto-mechanical behavior is of special interest in these applications, an in-depth understanding of the structure-property relations in MSEs as well as suitable theories for computing the effective macroscopic material response are required.MSEs represent a two-component system, in which micron-sized magnetizable particles are embedded in a soft polymer network. The flexibility of polymer sub-chains between cross-links allows a considerable degree of particle rearrangement under strong magnetic fields. As a result, the particles are prone to organize themselves into chain-like microstructures, which may considerably influence the coupled magneto-mechanical properties of MSEs. In this joint project, two work groups from the Leibniz-Institute for Polymer Research Dresden (IPF) and the Institute of Solid Mechanics of TU Dresden (IFKM) develop adapted modeling and simulation techniques to capture the hierarchical material structure, account for its evolution and predict the resulting macroscopic, strongly coupled magneto-mechanical behavior of MSEs. The theoretical predictions will be compared between both groups and with existing literature results. The modeling strategies which are pursued at IPF and IFKM will be combined to develop a unified, hybrid multiscale framework which allows for an accurate but efficient prediction of the macroscopic response of realistic MSE samples. The particular challenge is the simultaneous consideration of inhomogeneous, macroscopic magnetic and mechanical fields and their interaction with the underlying evolving microstructure. It is expected that the developement of the unified approach will benefit from the scientific exchange within the SPP that already started in the first funding period. The overall performance of the hybrid multiscale framework will be investigated by comparing simulation results for realistic MSE specimens with the experimentally observed behavior.