Song Byung-Keun, Yoon Ji-Young, Hong Seong-Woo, Choi Seung-Bok
Department of Mechanical Engineering, Incheon National University, Incheon 22012, Korea.
Department of Mechanical Engineering, Inha University, Incheon 22212, Korea.
Materials (Basel). 2020 Feb 20;13(4):953. doi: 10.3390/ma13040953.
A very flexible structure with a tunable stiffness controlled by an external magnetic stimulus is presented. The proposed structure is fabricated using two magnetic-responsive materials, namely a magnetorheological elastomer (MRE) as a skin layer and a magnetorheological fluid (MRF) as a core to fill the void channels of the skin layer. After briefly describing the field-dependent material characteristics of the MRE and MRF, the fabrication procedures of the structure are provided in detail. The MRE skin layer is produced using a precise mold with rectangular void channels to hold the MRF. Two samples are produced, namely with and without MRF, to evaluate the stiffness change attributed to the MRF. A magnetic field is generated using two permanent magnets attached to a specialized jig in a universal tensile machine. The force-displacement relationship of the two samples are measured as a function of magnetic flux density. Stiffness change is analyzed at two different regions, namely a small and large deformation region. The sample with MRF exhibits much higher stiffness increases in the small deformation region than the sample without MRF. Furthermore, the stiffness of the sample with MRF also increases in the large deformation region, while the stiffness of the sample without MRF remains constant. The inherent and advantageous characteristics of the proposed structure are demonstrated through two conceptual applications, namely a haptic rollable keyboard and a smart braille watch.
本文提出了一种具有非常灵活结构的装置，其刚度可通过外部磁刺激进行调节。该结构采用两种磁响应材料制成，即作为表层的磁流变弹性体（MRE）和作为芯层以填充表层空隙通道的磁流变液（MRF）。在简要描述了MRE和MRF的场依赖材料特性之后，详细介绍了该结构的制造过程。MRE表层使用带有矩形空隙通道的精密模具制作，用于容纳MRF。制作了两个样品，分别是含有和不含MRF的样品，以评估由MRF引起的刚度变化。在万能拉伸试验机中，通过连接到专用夹具上的两个永久磁铁产生磁场。测量了两个样品的力-位移关系随磁通密度的变化。在两个不同区域，即小变形区域和大变形区域，分析了刚度变化。含有MRF的样品在小变形区域的刚度增加比不含MRF的样品高得多。此外，含有MRF的样品在大变形区域的刚度也增加，而不含MRF的样品的刚度保持不变。通过两个概念应用，即触觉可滚动键盘和智能盲文手表，展示了所提出结构的固有优势特性。
