The in-plane stretching and compression mechanics of Negative Poisson’s ratio structures: Concave hexagon, star shape, and their combination

• Published in: Journal of alloys and compounds 2021-04, Vol.859, p.157840, Article 157840
• Main Authors: Zhao, Changfang, Zhou, Zhitan, Liu, Xinxin, Tang, Ziruo, Zhang, Kebin, Zhang, Peng, Ren, Jie, Liu, Zhilin, Le, Guigao, Zhong, Jianlin
• Format: Article
• Language: English
• Subjects: Beam theory (structures); Bending; Combination structure; Concave hexagon; Deformation; Elastic mechanics; Euler-Bernoulli beams; Mechanical properties; Mechanics (physics); Multi-cell structure; Negative Poisson’s ratio; Poisson's ratio; Star shape; Stretching
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2020.157840

Negative Poisson’s ratio structure is one of the international research hotspots, but there are still few reports on negative Poisson’s ratio combination structure. In this paper, two single cell structures (concave hexagonal structure and star shape structure) with connection beam and three nine-grid combination structures (X-type, H-type, Sd-type) were designed. To obtain the negative Poisson’s ratio mechanics, based on the Euler beam theory, the theoretical calculation method of single cell structure was established. By comparing the critical force, the sequence of bending and stretching/compression deformation was discussed. The mechanical properties of multi-cell structures were predicted by adopting the mixed law. The results show that the main deformation of the designed structures are bending, and the instability buckling occurs during compression. It is proved that the mechanical properties of multi-cell structures can be characterized by its single cell structure. The combination structure integrates the negative Poisson’s ratio mechanical properties of different single cell structures. An important application is that the mechanical properties of combination structures can be obtained by changing the proportion of single cell structures without changing the structure size. •In-plane elastic mechanics of negative Poisson’s ratio structure.•Concave hexagon, star shape single-cell and multi-cell structure.•Nine-grid multi-cell combination structure.•Deformation modes in compression and stretching.•Derivation of equivalent elastic mechanical parameters.