Auxetic materials exhibit interesting deformation characteristics and excellent mechanical properties. A novel combined tubular structure with tunable stiffness is proposed in this work, aiming to improve the bearing capacity and stability by length design of the central column. Specimens were fabricated via 3D printing technique. Experimental test was performed to study their mechanical property and deformation characteristics under uniaxial compression. The validity of the finite element model was proved by comparing the experimental result with simulation prediction. The compression process and stress-strain curve of the tubular structure with tunable stiffness exhibited four distinct stages (elastic, stiffness change, densification and buckling). Subsequently, a parametrical analysis was conducted to investigate the influences of the central connecting column on the stress-strain response, Poisson's ratio and stability of the structure. By properly choosing the length of the central connecting column, the tubular structure could possess tunable stiffness, higher stability and compressive capacity. Furthermore, this design concept could be of benefit to the development of adaptive structures, smart devices and applications for civil engineering and protective engineering.

拉胀材料表现出有趣的变形特性和优异的机械性能。本文提出了一种刚度可调的新型组合管状结构，旨在通过中柱的长度设计来提高承载能力和稳定性。标本是通过 3D 打印技术制造的。进行实验测试以研究其在单轴压缩下的力学性能和变形特性。通过将实验结果与仿真预测进行比较，证明了有限元模型的有效性。刚度可调的管状结构的压缩过程和应力应变曲线表现出四个不同的阶段（弹性、刚度变化、致密化和屈曲）。随后，进行了参数分析，研究了中心连接柱对结构应力应变响应、泊松比和稳定性的影响。通过适当地选择中央连接柱的长度，管状结构可具有可调刚度，更高的稳定性和压缩容量。此外，这种设计理念可能有利于土木工程和防护工程的自适应结构、智能设备和应用的开发。