As a kind of metamaterials, the negative Poisson’s ratio foams, which expand (shrink) in the transverse direction when stretched (compressed) in the longitudinal direction, have many potential applications in the fields of aerospace, mechanical and biomedical engineering etc... In this paper, the out-of-plane crushing behaviors of four types of the orthogonal isotropic NPR convex-concave foams (CCF) was extensively studied using an electronic universal testing machine and Instron machine at different strain rates where each test was conducted at a constant compressive velocity under uniaxial compression. Strain rate effect on mechanical properties of these foams is experimentally studied. When the strain rate increases, the compressive force enhancement of the foams is obvious and varies with different specimens. The difference in energy absorption and deformation patterns for these foams between quasi-static and dynamic loading conditions is also analyzed. We find that the deformation patterns for the specimens are not only related to the compressive velocities but also the topologies of the specimens. The research in this paper are expected to be meaningful for the optimization design of the foam structures/materials widely used in the fields of aerospace, mechanical and biomedical engineering etc.

中文翻译：

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应变率对具有可调负泊松比的 3D 打印超材料泡沫的机械性能的影响

作为一种超材料，负泊松比泡沫在纵向拉伸（压缩）时在横向膨胀（收缩），在航空航天、机械和生物医学工程等领域具有许多潜在的应用......本文使用电子万能试验机和 Instron 机在不同应变率下广泛研究了四种正交各向同性 NPR 凸凹面泡沫 (CCF) 的面外破碎行为，每次试验均在恒定单轴压缩下的压缩速度。通过实验研究了应变速率对这些泡沫机械性能的影响。当应变速率增加时，泡沫的压缩力增强是明显的，并且随不同的试样而变化。还分析了这些泡沫在准静态和动态加载条件下的能量吸收和变形模式的差异。我们发现试样的变形模式不仅与压缩速度有关，而且与试样的拓扑结构有关。预计本文的研究对航空航天、机械和生物医学工程等领域广泛应用的泡沫结构/材料的优化设计具有重要意义。