Advanced Impact Resistant Auxetic Materials via Additive Manufacturing

通常被称为“超材料”或“负泊松比材料”的相变材料在其对变形的响应方面是违反直觉的。当被拉伸时，它们会膨胀，相反地，当被压缩时，它们会收缩。这种性能使它们对于冲击应用非常有吸引力;在以高速率压缩加载时，它们将倾向于提供增加的阻力。因此，目前有几种商业拉胀产品，特别是世界上最大的制造商生产的运动鞋。 然而，拉胀材料的更广泛应用直到现在才随着增材制造（AM）的出现而获得显著关注。AM是一种制造方法，可以用各种材料打印出非常复杂的几何形状。最近，AM已被应用于制造拉胀剂，目的是利用AM的优势，即打印弯曲和渐变材料的能力。然而，目前的努力已被限制到相对小的尺寸和/或尚未在规模上进行实验测试。需要一种设计工具来弥合实验室规模的AM拉胀和具有大尺寸（几十厘米量级）的工程拉胀商业化产品之间的技术差距。 所提出的工作的短期目标是开发一种经过验证的设计工具，可以虚拟地模拟拉胀材料。需要这种设计工具来加速用于冲击应用的拉胀产品的开发。长期目标是利用增材制造的优势，解决众所周知的冲击防护装备不平等问题，其中女性专用运动鞋和防弹衣是众所周知的需求。由于针对性产品的制造成本很高，这些需求目前很少得到满足。通过使用所提出的设计工具，这项工作的目的是提供一种技术手段，加快这些所需的鞋类和装甲产品的开发更现实。

Auxetic materials, often referred to as “metamaterials” or “negative Poisson's ratio materials”, are counter-intuitive in their response to deformation. Upon being stretched they will expand and conversely will contract when compressed. This behavior makes them very attractive for impact applications; upon being compressively loaded at high rates they will tend to supply increased resistance. As such there are several commercial auxetic products currently available, notably athletic footwear produced by the world's largest manufacturer. However, broader application of auxetic materials is only now garnering significant attention with the advent of additive manufacturing (AM). AM is a manufacturing method in which very complex geometries can be printed out of a wide variety of materials. Recently, AM has been applied to the manufacture of auxetics with the aim of leveraging the advantages of AM, namely the ability to print curved and graded materials. However, the current efforts have been limited to relatively small sizes and/or have not been experimentally tested at scale. A design tool is needed to bridge the technology gap between lab-scale AM auxetics and engineering auxetic commercially-ready products that have large sizes (on the order of tens of centimeters). The short-term objectives of the proposed work is to develop a validated design tool that can virtually simulate auxetic materials. This design tool is needed to accelerate the development of auxetic products for impact applications. The long-term objective is to harness the advantages of AM to address a well-known inequality in impact protective gear where female-specific athletics footwear and ballistic body armor are well-known needs. These needs are currently very sparsely filled due to the high manufacturing costs for sex-specific products. Through the use of the proposed design tool, this work aims to provide a technological means of accelerating the development of these needed footwear and armor products more realistic.