Conformal topology optimization of multi-material ferromagnetic soft active structures using an extended level set method
Conformal topology optimization of multi-material ferromagnetic soft active structures using an extended level set method
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DOI：
10.1016/j.cma.2021.114394
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发表时间：
2022-02
影响因子：
7.2
通讯作者：
Jiawei Tian;Manqi Li;Zhong Han;Yong Chen;X. Gu;Q. Ge;Shikui Chen
中科院分区：
文献类型：
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作者：
Jiawei Tian;Manqi Li;Zhong Han;Yong Chen;X. Gu;Q. Ge;Shikui Chen
铁磁软活性结构使用嵌入在软聚合物基质中的铁磁颗粒，可以产生灵活的运动和改变配置远程，快速，和生物友好的施加磁场。为了实现所需的运动，这些软有源结构可以通过定制铁磁软聚合物的布局来设计。虽然已经设计和制造了许多磁性软有源结构，但它们受到开发人员直觉和经验的限制。结构拓扑优化是一种通过优化材料布局实现创新结构的有效方法，为铁磁驱动有源结构的设计开辟了新的途径。针对柔性机器人普遍采用的薄壳结构，采用扩展水平集方法（X-LSM）和共形几何理论对流形上的铁磁柔性主动结构进行拓扑优化.通过求解一个带保角因子的修正的Hamilton-Jacobi方程，将三维自由曲面上的边界演化问题转化到二维矩形平面上。本文首次在X-LSM框架下实现了协调水平集（RLS）方法，使自由表面上的多材料铁磁软有源结构的设计成为可能。设计目标由满足运动学要求的子目标函数和满足最小柔度的子目标函数组成。利用材料时间导数和伴随变量法分析了形状敏感性。将该方法应用于几种单材料和多材料铁磁软有源结构的设计。两种拓扑优化的设计已经使用功能性3D打印技术或所谓的4D打印来打印，以物理地实现具有内置功能的柔性有源结构。数值验证和实验验证的结果表明，所提出的设计和制造框架的有效性。
Ferromagnetic soft active structures using embedded ferromagnetic particles in the soft polymer matrix can generate flexible locomotion and change configurations remotely, rapidly, and biologically friendly with an applied magnetic field. To achieve the desired motion, these soft active structures can be designed by tailoring the layouts of the ferromagnetic soft polymer. Although many magnetic soft active structures have been designed and fabricated, they are limited by the developer’s intuition and experience. Structural topology optimization has become a promising method to achieve innovative structures by optimizing the material layout, opening a new path for architecting ferromagnetic-driven active structures. Given the widespread adoption of thin-shell structures for soft robots, the extended level set method (X-LSM) and conformal geometry theory are employed to perform topology optimization of the ferromagnetic soft active structures on manifolds. The boundary evolution on a free-form 3D surface can be transferred into a 2D rectangular plane by solving a modified Hamilton–Jacobi equation weighted by conformal factors. The reconciled level set (RLS) method is firstly implemented within the X-LSM framework in this paper to enable the design of multi-material ferromagnetic soft active structures on free-from surfaces. The design objective consists of a subobjective function for kinematic requirement and a subobjective function for minimum compliance. The shape sensitivity was analyzed using the material time derivative and the adjoint variable approach. The proposed method was applied to design several single and multi-material ferromagnetic soft active structures. Two topologically optimized designs have been printed using functional 3D printing technology, or the so-called 4D printing, to physically realize soft active structures with built-in functionalities. The results of the numerical verification and experimental validation demonstrate the effectiveness of the proposed design and fabrication framework.