Micromechanics Study on Actuation Efficiency of Hard-Magnetic Soft Active Materials
Micromechanics Study on Actuation Efficiency of Hard-Magnetic Soft Active Materials
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DOI：
10.1115/1.4047291
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发表时间：
2020-06
期刊：
影响因子：
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通讯作者：
Rundong Zhang;Shuai Wu;Qiji Ze;R. Zhao
中科院分区：
文献类型：
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作者：
Rundong Zhang;Shuai Wu;Qiji Ze;R. Zhao
硬磁软活性材料由于具有不受约束、驱动速度快、可逆、形状变化大等优点，近年来引起了广泛的研究兴趣。这些材料通常是通过在软基质中嵌入硬磁性颗粒来制造的。由于驱动是通过将外加磁场对磁性颗粒产生的微扭矩传递到软矩阵来实现的，因此驱动取决于磁性颗粒与软矩阵之间的相互作用。在本文中，我们通过具有代表性的体元模拟，利用微观力学方法研究了这种相互作用如何影响驱动效率。微观力学分析表明，质点旋转对驱动效率，即转矩传递效率起着至关重要的作用。特别是，较大的局部粒子在矩阵中的旋转会降低有效驱动效率。微观力学模拟进一步表明，颗粒向基体传递转矩的效率与颗粒体积分数、基体模量、外加磁场强度以及颗粒形状有关。在微观力学模拟的基础上，建立了转矩传递效率与颗粒体积分数、基体模量和外加磁场强度之间关系的简单理论模型。我们期望通过对硬磁软活性材料驱动效率的研究，为不同应用场合下材料制造参数的确定提供优化和设计指导。
Hard-magnetic soft active materials have drawn significant research interest in recent years due to their advantages of untethered, rapid and reversible actuation, and large shape change. These materials are typically fabricated by embedding hard-magnetic particles in a soft matrix. Since the actuation is achieved by transferring the microtorques generated on the magnetic particles by the applied magnetic field to the soft matrix, the actuation depends on the interactions between the magnetic particles and the soft matrix. In this paper, we investigate how such interactions can affect the actuation efficiency by using a micromechanics approach through the representative volume element simulations. The micromechanics reveals that particle rotations play an essential role in determining the actuation efficiency, i.e., the torque transmission efficiency. In particular, a larger local particle rotation in the matrix would reduce the effective actuation efficiency. Micromechanics simulations further show that the efficiency of the torque transmission from the particles to the matrix depends on the particle volume fraction, the matrix modulus, the applied magnetic field strength, as well as the particle shape. Based on the micromechanics simulations, a simple theoretical model is developed to correlate the torque transmission efficiency with the particle volume fraction, the matrix modulus, as well as the applied magnetic field strength. We anticipate this study on the actuation efficiency of hard-magnetic soft active materials would provide optimization and design guidance to the parameter determination for the material fabrication for different applications.