Hiptmair F, Major Z, Haßlacher R, Hild S
Institute of Polymer Product Engineering, Johannes Kepler University Linz, Altenbergerstr. 69, 4040 Linz, Austria.
Institute of Polymer Science, Johannes Kepler University Linz, Altenbergerstr. 69, 4040 Linz, Austria.
Rev Sci Instrum. 2015 Aug;86(8):085107. doi: 10.1063/1.4927714.
Magnetoactive elastomers (MAEs) are a class of smart materials whose mechanical properties can be rapidly and reversibly changed by an external magnetic field. Due to this tunability, they are useable for actuators or in active vibration control applications. An extensive magnetomechanical characterization is necessary for MAE material development and requires experiments under cyclic loading in uniform but variable magnetic fields. MAE testing apparatus typically rely on fields of adjustable strength, but fixed (transverse) direction, often provided by electromagnets. In this work, two permanent magnet flux sources were developed as an add-on for a modular test stand, to allow for mechanical testing in uniform fields of variable direction. MAE specimens, based on a silicone matrix with isotropic and anisotropic carbonyl iron particle distributions, were subjected to dynamic mechanical analysis under different field and loading configurations. The magneto-induced increase of stiffness and energy dissipation was determined by the change of the hysteresis loop area and dynamic modulus values. A distinct influence of the composite microstructure and the loading state was observed. Due to the very soft and flexible matrix used for preparing the MAE samples, the material stiffness and damping behavior could be varied over a wide range via the applied field direction and intensity.
磁致伸缩弹性体（MAEs）是一类智能材料，其机械性能可通过外部磁场快速且可逆地改变。由于这种可调性，它们可用于致动器或主动振动控制应用中。对MAE材料的开发而言，广泛的磁机械特性描述是必要的，这需要在均匀但可变的磁场中进行循环加载实验。MAE测试设备通常依赖于强度可调但方向固定（横向）的磁场，这种磁场通常由电磁铁提供。在这项工作中，开发了两个永磁通量源作为模块化测试台的附加装置，以便在可变方向的均匀磁场中进行机械测试。基于具有各向同性和各向异性羰基铁颗粒分布的硅酮基体的MAE试样，在不同的磁场和加载配置下进行了动态力学分析。通过磁滞回线面积和动态模量值的变化确定了磁致刚度增加和能量耗散情况。观察到了复合材料微观结构和加载状态的显著影响。由于用于制备MAE样品的基体非常柔软且具有柔韧性，通过施加的磁场方向和强度，材料的刚度和阻尼行为可以在很宽的范围内变化。
