Shock compression of auxetic metamaterials made by additive manufacturing

This proposal concerns to study the dynamic response of additively manufactured auxetic metamaterials made from metal. This particular class of lattice structure metamaterials displays unconventional material behaviour: it contracts laterally rather than expands upon compression. As a consequence, specific strength and stiffness are potentially better than for other lattice or porous materials, which makes these materials interesting for light-weight crash absorbers. An important question in this context is, from what critical velocity onwards the auxetic structural response is replaced by a cell collapse mechanism. Real-time visualization of this mechanism in the bulk of the material can only be performed with X-ray imaging. Preliminary investigations of the dynamic effects have shown that critical velocities are ~100-200 m/s, which can be attained with the gas gun setup at ID19.

本提案旨在研究金属基增材制造负泊松比超材料（auxetic metamaterials）的动态响应。这类特殊的点阵结构超材料展现出非常规力学行为：受压缩时会发生横向收缩而非膨胀。因此其比强度与比刚度性能优于其他点阵或多孔材料，使得这类材料在轻量化吸能缓冲装置中极具应用潜力。在此研究背景下，一个关键问题是：当临界速度达到何值时，负泊松比结构的力学响应会转变为胞元坍塌机制。对材料内部该机制的实时可视化观测，仅能通过X射线成像技术实现。前期针对动态效应的研究表明，临界速度约为100-200 m/s，该速度区间可通过ID19光束线的气枪加载装置达成。