Designing New Types of Cellular Hybrids for Lightweighting Applications

考虑到我们迫在眉睫的经济和环境挑战，一个关键的技术问题是开发新材料，在较低的生态足迹下提高性能-换句话说，找到用更少的钱做更多事情的方法。材料性能空间达到新区域的巨大潜力来自混合材料的开发，这种材料将两种或两种以上材料组合在一起，以创建两种材料中任何一种单独无法提供的材料性能组合。为了降低汽车和航空航天领域的能源消耗，将材料和开放空间结合在一起的轻质蜂窝混合动力汽车尤其具有吸引力。这项NSERC Discovery拨款主要用于先进的细胞混合材料，因为细胞混合材料的内部结构提供了一种方法，可以使用基于形状的设计参数来显著改变材料的有效性能，从而允许它们专门为系统质量最小化的结构应用量身定做。这笔赠款中开发的材料将具有更高的性能和更低的环境影响，以便为加拿大航空航天和制造部门提供竞争优势。航空航天是加拿大的战略部门，根据加拿大航空航天工业协会的数据，加拿大为80000多加拿大人提供了高质量的就业机会，创造了236亿美元的总收入(2008年)。航空航天部门面临的一个主要挑战是制造具有最佳强度、刚度和密度组合的结构材料。微桁架蜂窝材料具有完全三角化的结构，使其成为通过轻型蜂窝混合体传递外部载荷的最有效的结构方式。这可以使它们比其他轻质蜂窝材料(如金属泡沫)的效率高出一个数量级以上，并实现更好的刚度质量比和强度质量比。然而，它们广泛应用的关键障碍是，用高性能材料制造最佳效率的微桁架结构往往是不可能的。在之前的探索基金中，我们已经找到了绕过这个问题的方法。我们使用添加剂制造来创造一种最高效的聚合物支架，在其上电沉积超高强度纳米晶体材料。这些材料目前正在与领先的加拿大航空航天和纳米技术公司合作开发。另一方面，一般制造业，特别是汽车行业，也需要低成本的方法来生产对环境影响最小的轻质结构材料。随机蜂窝也是由申请人的研究小组发明的，它只需要最少的资本设备就可以制造出来：热塑性珠子在加热的平板之间熔化，然后将它们拉到固定距离，然后让它们冷却。冻结在一起的网状结构自发地从金属板上分离出来，用一种材料制成热塑性夹层板，核心和面板完全集成。聚丙烯随机蜂窝的机械性能可与商用聚丙烯蜂窝相媲美，并显著高于传统的聚丙烯泡沫塑料，还有一个额外的优势，即它们可以在尖锐的拐角处模压。一家名为FlyTechnologies的衍生公司已经成立，将这些材料商业化，我们目前正在与一家领先的汽车零部件制造商合作制造这些材料。

Given our looming economic and environmental challenges, a key technological issue is to develop new materials that have enhanced performance at a lower ecological footprint - in other words, discovering ways to do more with less. A very rich potential for reaching new regions of material property space comes from the development of hybrids, which combine two or more materials in order to create material property combinations not offered by either material alone. Lightweight cellular hybrids, created by combining material and open space are particularly attractive in order to reduce the energy consumption in the automotive and aerospace sectors. This NSERC Discovery grant is focussed on advanced cellular hybrid materials because the internal architecture of cellular hybrids provides a means for using shape-based design parameters to dramatically alter the effective properties of a material, allowing them to be specifically tailored for structural applications where minimized system mass is a priority. The materials developed in this grant will have enhanced performance and lower environmental impact in order to give a competitive advantage to the Canadian Aerospace and Manufacturing sectors. Aerospace is a strategic sector for Canada, which, according to the Aerospace Industries Association of Canada, provides high-quality employment for over 80000 Canadians and generates total revenues of $23.6 billion (2008). A major challenge for the Aerospace sector is to manufacture structural materials having the best combinations of strength, stiffness, and density. Microtruss cellular materials have fully triangulated architectures making them the most structurally efficient way of having externally applied loads transmitted through a lightweight cellular hybrid. This can make them more than an order of magnitude more efficient than other lightweight cellular materials, such as metallic foams, and enables much better stiffness-to-mass and strength-to-mass ratios. The critical barrier to their widespread application, however, is that optimally efficient microtruss architectures are often impossible to manufacture from high performance materials. We have found a way to circumvent this problem in the previous Discovery Grant. We use additive manufacturing to create an optimally efficient polymeric scaffold, upon which ultrahigh strength nanocrystalline materials are electrodeposited. These materials are currently being developed in partnership with leading Canadian Aerospace and Nanotechnology companies. At the other end of the spectrum, low cost methods to produce lightweight structural materials having minimized environmental impact are also needed for the Manufacturing sector in general and the Automotive sector in particular. Stochastic honeycombs, also invented by the applicant's research group, need only minimal capital equipment to be manufactured: thermoplastic beads are melted between heated plates, which are then pulled to a fixed distance apart and allowed to cool. The frozen-in web structure spontaneously de-bonds from the metal plates, creating a thermoplastic sandwich panel out of a single material with fully integrated core and facesheets. The mechanical properties of polypropylene stochastic honeycombs are comparable to those seen for commercial polypropylene honeycombs and significantly higher than those of conventional polypropylene foams, with the additional advantage that they can be moulded around sharp corners. A spin-off company, FlyTechnologies, has been formed to commercialize these materials and we are currently working with a leading auto parts manufacturer to fabricate them.