Directional Architecture in Tensegrity Systems: Towards ‘Bone & Muscle’ Metamaterials

在过去的十年中，机械超材料领域取得了巨大的进步，其总体目标是创造新一代多功能和自适应高性能材料。虽然表现出了突出的个体特性（例如，超强纳米晶格，形状变形折纸结构），但由于根本不同的设计原则，这些特性在很大程度上是不相容的。迄今为止，对于如何在机械超材料中协同实现真正的多功能性，还没有一个整体的概念。生物承重结构，如骨和肌肉生理学，是基于所谓的拉伸完整性或张拉整体结构，并独特地将有效的材料利用与适应各种多功能任务的能力结合起来。与已建立的超材料结构相反，张拉整体由相互隔离的不连续压缩构件组成，仅通过连续的张拉构件网络连接。尽管其机械独特的拓扑结构，张拉整体体尚未被探索作为超材料设计范式；受生物骨骼和肌肉生理学的启发，amy - noether - group将张拉整体原理和定向材料、结构和功能设计结合成一种新型多功能张拉整体超材料的建筑概念。跨越学科和尺度，引人注目的物理特性依赖于高度定向效应和低维结构——从蜂巢无与伦比的压缩稳定性到碳纳米管的极端导电性。提出的概念提供了一种跨学科的适用方法，利用张拉整体原理使这些效应在体积超材料中可访问。特别是，该提案的工作计划侧重于纳米和微张拉整体的发展，这些张拉整体是由聚合物3d打印并热解成陶瓷的。因此，张拉整体载荷传递机制应利用热解收缩效应，通过可控的超高系绳应变诱导材料微观结构的定向可定制性。预计这将为开发极端取向和尺寸相关的材料特性提供途径，包括类似碳纳米管的强度和刚度。同时，对绳系应变和弹性杆屈曲机制的控制有望在具有本质脆性的组成材料的基础上实现大范围的稳定可逆变形。基于此，建筑概念将在随后的努力中扩展到结构和功能尺度，其中可以采用纤维驱动原理来设计人造肌肉和压缩杆，可以模仿动物骨骼等自然细胞层次结构。

The field of mechanical metamaterials has over the last decade seen dramatic progress, with the overarching goal to create a new generation of multifunctional and adaptive high-performance materials. Having demonstrated outstanding individual properties (e.g. ultra-strong nanolattices, shape-morphing origami structures), those characteristics are however largely incompatible due to fundamentally different design principles. To this day, there is no holistic concept how to synergetically implement true multifunctionality in mechanical metamaterials. Biological load-bearing structures, like bone-and-muscle physiologies, are based on so-called tensile-integrity, or tensegrity architectures and uniquely combine efficient material utilization with the ability to accommodate a broad variety of multifunctional tasks. In contrast to established metamaterial architectures, tensegrities are comprised of discontinuous compression members that are isolated from each other and only connected through a continuous network of tension members. Despite their mechanically unique topology, tensegrities have yet to be explored as metamaterial designs paradigm; the Emmy-Noether-Group aims to change thisInspired by biological bone-and-muscle physiologies, this Emmy-Noether-Group coalesces tensegrity principles and directional material, structure, and function designs into an architecture concept for a novel class of multifunctional tensegrity metamaterials. Across disciplines and scales, striking physical characteristics rely on highly directional effects and low-dimensional structures - from the unrivaled compressive stability of honeycombs to the extreme conductivity of carbon nanotubes. The presented concept provides an interdisciplinarily applicable approach that utilizes tensegrity principles to make these effects accessible in a volumetric metamaterial. In particular, the work program of this proposal focuses on the development of nano- and micro-tensegrities which are 3D-printed from polymer and pyrolyzed into ceramics. Thereby, tensegrity load-transfer mechanisms shall exploit pyrolysis contraction effects to induce directional material microstructure tailorability via controlled ultra-high tether straining. This is anticipated to provide a pathway to exploit extreme orientation- and size-dependent material properties, including CNT-like strength and stiffness. Simultaneously, control of tether straining and elastic bar buckling mechanisms are anticipated to program a wide range of stable reversible deformability with the intrinsically brittle constituent material. Based on that, the architecture concept will in subsequent efforts be expanded to the structure and function scale, where fiber actuation principles may be adopted to design tethers as artificial muscles and compressive bars could be modeled after natural cellular hierarchies like animal bones.