Le Ferrand Hortense, Riley Katherine S, Arrieta Andres F
School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore.
School of Mechanical Engineering, Purdue University, 585 Purdue Mall, West Lafayette, IN 47907, United States of America.
Bioinspir Biomim. 2022 May 12;17(4). doi: 10.1088/1748-3190/ac61ea.
Plants are inspiring models for adaptive, morphing systems. In addition to their shape complexity, they can respond to multiple stimuli and exhibit both fast and slow motion. We attempt to recreate these capabilities in synthetic structures, proposing a fabrication and design scheme for multi-stimuli and multi-temporal responsive plant-inspired composites. We leverage a hierarchical, spatially tailored microstructural and compositional scheme to enable both fast morphing through bistability and slow morphing through diffusion processes. The composites consisted of a hydrogel layer made of gelatine and an architected particle-reinforced epoxy bilayer. Using magnetic fields to achieve spatially distributed orientations of magnetically responsive platelets in each epoxy layer, complex bilayer architectural patterns in various geometries were realised. This feature enabled the study of plant-inspired complex designs,finite element analysis and experiments. We present the design and fabrication strategy utilizing the material properties of the composites. The deformations and temporal responses of the resulting composites are analysed using digital image correlation. Finally, we model and experimentally demonstrate plant-inspired composite shells whose stable shapes closely mimic those of the Venus flytrap, while maintaining the multi-stimuli and multi-temporal responses of the materials. The key to achieving this is to tune the local in-plane orientations of the reinforcing particles in the bilayer shapes, to induce distributed in-plane mechanical properties and shrinkage. How these particles should be distributed is determined using finite element modelling. The work presented in this study can be applied to autonomous applications such as robotic systems.
植物是自适应变形系统的启发性模型。除了其形状复杂性外，它们还能对多种刺激做出反应，并展现出快速和慢速运动。我们试图在合成结构中重现这些能力，提出一种用于多刺激和多时间响应的受植物启发的复合材料的制造和设计方案。我们利用一种分层的、空间定制的微观结构和组成方案，通过双稳态实现快速变形，并通过扩散过程实现慢速变形。这些复合材料由明胶制成的水凝胶层和一种精心设计的颗粒增强环氧树脂双层组成。利用磁场实现每个环氧树脂层中磁响应薄片的空间分布取向，实现了各种几何形状的复杂双层结构图案。这一特性有助于对受植物启发的复杂设计、有限元分析和实验进行研究。我们展示了利用复合材料材料特性的设计和制造策略。使用数字图像相关技术分析所得复合材料的变形和时间响应。最后，我们通过建模和实验展示了受植物启发的复合壳，其稳定形状与捕蝇草的形状非常相似，同时保持了材料的多刺激和多时间响应。实现这一点的关键是调整双层形状中增强颗粒的局部面内取向，以诱导分布的面内机械性能和收缩。这些颗粒应如何分布通过有限元建模来确定。本研究中提出的工作可应用于机器人系统等自主应用。
