Towards Multiscale Mechanical Design of Hierarchical Cellular Materials

木材是一种非凡的多孔材料的一个例子，它是高度多孔的，但重量轻，坚固，坚硬，坚韧，这些机械性能的组合在合成多孔材料中还没有实现。该提案的目的是使用计算和实验分析，以创建一个基本的了解如何多尺度结构组织的木材，从分子到宏观，确定其机械性能，并发现设计原则，通常适用于多尺度层次设计的合成蜂窝材料。这项研究的成果将包括：（1）用于聚合物材料从原子到宏观的多尺度建模的模拟工具，（2）木材从分子到木材组织的定量结构模型，（3）木材的多尺度结构-性质关系，以及（4）合成细胞材料的分级设计指南。如果成功，这一研究不仅将加深我们对木材独特力学性能的理解，而且将为分析和设计具有分级结构的聚合物材料提供理论工具。 它将有助于下一代多尺度、多功能复合材料的发展。此外，对木材层次结构的重要性的基本理解对于那些对控制次生细胞壁形成的遗传机制感兴趣的植物生物学家来说也是至关重要的。模拟工具可以深入了解木材成分和结构如何决定其机械性能，也可以告知生物学家如何修改木材成分以增强特定的最终用途。这项研究必然将材料科学和机械工程与生物学相结合，因此，提供了一个独特的机会来建立一个多学科的学习和培训计划，超越学科之间的传统界限，为学生提供团队研究和职业发展的综合方法。

Wood is an example of an extraordinary cellular material that is highly porous yet lightweight, strong, stiff, hard and tough, a combination of mechanical properties that have not been achieved in synthetic porous materials. The objective of this proposal is to use computational and experimental analyses to create a fundamental understanding of how the multiscale structural organization of wood, from the molecular to the macroscopic, determines its mechanical properties and to discover design principles that may generally apply to multiscale hierarchical design of synthetic cellular materials. The outcomes of this research will include: (1) a simulation tool for multiscale modeling of polymeric materials from the atomic to the macroscopic, (2) a quantitative structural model of wood from molecules to wood tissue, (3) the multiscale structure-property relationship of wood, and (4) guidelines for hierarchical design of synthetic cellular materials.If successful, this research will not only enhance our understanding of the unique mechanical properties of wood, but will also provide a theoretical tool for analysis and design of hierarchically-structured polymeric materials. It will contribute to the development of next generation multiscale, multifunctional composite materials. In addition, a fundamental understanding of the importance of the hierarchical structure of wood is also crucial for plant biologists who are interested in the genetic mechanisms that govern secondary cell wall formation. Simulation tools that give insight into how wood composition and structure determine its mechanical properties will also inform biologists about how wood composition can be modified to enhance specific end uses. This research necessarily merges materials science and mechanical engineering with biology, and, therefore, provides a unique opportunity to establish a multidisciplinary learning and training program that transcends the traditional boundaries between academic disciplines and offer students an integrated approach of team research and career development.