I-Corps: Auxetic Structures for Practical Applications

I-Corps项目更广泛的影响/商业潜力在于开发适合广泛应用的伸展复合材料的框架(伸展材料在沿其长度方向拉伸时在宽度方向上变厚，在纵向压缩时变薄)。该项目有可能在研究、设计和制造伸展材料方面发挥关键作用。商业潜力横跨几个不同的行业，在这些行业中，人们寻求改善抗冲击性、抗压痕性、能量和吸声性能以及同向碎裂胶曲率。最大的商业影响将出现在需要这些性能组合的应用中，包括个人防护设备，以及汽车和航空航天部门的结构和噪音和振动应用。这个i-Corps项目的中心是为广泛的商业应用开发负泊松比(即拉伸)复合材料。这项技术的动力来自于拉伸材料的许多诱人的机械性能。理论上，与泊松比为正的材料相比，负泊松比材料具有更高的硬度、抗冲击性、断裂韧性、吸声性能和剪切弹性。此外，拉伸材料在弯曲时表现出同向碎裂的曲率，这意味着它们可以弯曲成双曲形状，从而消除了制造弯曲或圆顶形状零件所需的一些加工。由于目前可用的大多数伸展材料和结构是多孔的，且刚度较低，实际结构应用在很大程度上仍然难以实现。该项目代表了一条直接通向结构的途径，该结构利用了商业应用中的膨胀材料的好处。这种方法的独特之处在于使用折纸图案，这些图案在折叠时显示出伸展行为，以告知设计和开发一类新的负泊松比结构。这些结构可以通过折叠和/或添加制造来实现，材料和长度比例的选择基于特定的应用。

The broader impact/commercial potential of this I-Corps project lies in the contribution of a framework for the development of auxetic composites that are suitable for a broad range of applications (an auxetic material, when stretched along its length, becomes thicker in width-wise directions and it becomes thinner when compressed lengthwise). This project has the potential to be pivotal in the way that auxetic materials are studied, designed and fabricated. The commercial potential spans several different industries where improved impact resistance, indentation resistance, energy and sound absorption properties, and synclastic curvature are sought. The greatest commercial impacts will be in applications requiring a combination of these properties, including personal protective equipment, and structural and noise and vibration applications in the automotive and aerospace sectors.This I-Corps project is centered on the development of negative Poisson's ratio (i.e. auxetic) composites for a wide range of commercial applications. The technology is motivated by the many attractive mechanical properties of auxetic materials. In theory, a negative Poisson's ratio material has improved hardness, impact resistance, fracture toughness, sound absorbing properties, and shear modulus over one with a positive Poissons ratio. In addition, auxetic materials exhibit synclastic curvature when bent, which means that they can be bent into a doubly curved shape, thus eliminating some of the machining necessary to fabricate curved or dome-shaped parts. Since most currently available auxetic materials and structures are porous and have low stiffness, practical structural applications remain largely elusive. This project represents a direct route to structures that exploit the benefits of auxetic materials for commercial applications. The uniqueness of the approach lies in the use of origami patterns which exhibit auxetic behavior when folded to inform the design and development of a new class of negative Poisson's ratio structures. Those structures can be realized through folding and/or additive manufacturing, with the material and length scale selection based on the specific application.