Nash Richard J, Li Yaning
Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA, 02215, USA.
Nat Commun. 2024 Aug 14;15(1):6994. doi: 10.1038/s41467-024-50664-8.
By incorporating concepts from auxeticity, kinematic constraints, pre-tension induced compression (PIC), and suture tessellations, tiled sandwich composites are designed, demonstrating behaviors attributed to the synergy between auxeticity and pre-tension induced contact and compression, simultaneously triggered by a threshold strain. The designs can theoretically achieve on-demand Poisson's ratio in the widest range (-∞, +∞), and once triggered, the Poisson's ratio is stable under large deformation. Also, once the overall strain goes beyond the threshold, the designs enter into a PIC stage, ensuring the middle soft layer takes the tensile load, while the tiles are under compression via contact and the 3D articulation of the tooth-channel pairs. In this PIC stage, the tooth-channel pairs provide kinematic constraints via the contact and relative sliding between teeth and channels. The deformation mechanisms and mechanical properties of them are systematically explored via an integrated analytical, numerical, and experimental approach. Mechanical experiments are performed on 3D printed specimens. It is found that the length aspect ratio and the obliqueness of the teeth significantly influence the constraint angle and therefore the auxeticity and strength of the designs.
通过融合来自负泊松比、运动学约束、预拉伸诱导压缩（PIC）和缝合镶嵌等概念，设计出了平铺夹层复合材料，展示了由阈值应变同时触发的负泊松比与预拉伸诱导接触和压缩之间协同作用所产生的行为。这些设计理论上可以在最宽范围（-∞，+∞）内实现按需泊松比，并且一旦触发，泊松比在大变形下是稳定的。此外，一旦总应变超过阈值，这些设计就进入PIC阶段，确保中间软层承受拉伸载荷，而瓦片通过接触以及齿 - 槽对的三维铰接处于压缩状态。在这个PIC阶段，齿 - 槽对通过齿与槽之间的接触和相对滑动提供运动学约束。通过综合分析、数值和实验方法系统地探索了它们的变形机制和力学性能。对3D打印试样进行了力学实验。发现齿的长径比和倾斜度显著影响约束角，从而影响设计的负泊松比和强度。
