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，以更低的生态足迹提高性能-换句话说，找到用更少的东西做更多的事情的方法。材料性能空间的新领域的巨大潜力来自混合动力汽车的开发，其结合联合收割机两种或多种材料，以产生任一种材料单独不能提供的材料性能组合。通过结合材料和开放空间创建的轻质蜂窝混合动力车特别有吸引力，以减少汽车和航空航天领域的能源消耗。该NSERC发现补助金专注于先进的蜂窝混合材料，因为蜂窝混合材料的内部结构提供了一种使用基于形状的设计参数来显着改变材料有效特性的方法，使它们能够专门针对优先考虑最小化系统质量的结构应用而量身定制。该补助金开发的材料将具有更高的性能和更低的环境影响，以使加拿大航空航天和制造业具有竞争优势。航空航天是加拿大的一个战略部门，根据加拿大航空航天工业协会的数据，航空航天为80000多名加拿大人提供了高质量的就业机会，并产生了236亿美元的总收入（2008年）。航空航天领域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形的结构，使其成为通过轻质蜂窝混合体传递外部施加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（例如金属泡沫）更有效一个数量级以上，并且能够实现更好的刚度质量比和强度质量比。然而，其广泛应用的关键障碍是，最佳效率的微桁架架构通常不可能由高性能材料制造。我们已经找到了一种方法来规避这个问题在以前的发现补助金。我们使用增材制造来创建最佳效率的聚合物支架，在其上电沉积高强度纳米晶材料。这些材料目前正在与加拿大领先的航空航天和纳米技术公司合作开发。另一方面，制造业和汽车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，只需要最少的资本设备来制造：热塑性珠在加热的板之间熔化，然后将其拉到固定的距离并冷却。冻结的网状结构自发地从金属板上脱粘，从具有完全集成的芯和面板的单一材料中产生热塑性夹层板。聚丙烯随机蜂窝体的机械性能与商业聚丙烯蜂窝体的机械性能相当，并且显著高于常规聚丙烯泡沫体的机械性能，另外的优点是它们可以围绕尖角模制。我们成立了一家衍生公司FlyTechnologies来将这些材料商业化，目前我们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.