Bridging finite element-molecular dynamics method for multiscale modeling of solids

纳米技术最近成为一个快速发展的领域。纳米科学和纳米技术的应用是巨大的：纳米材料用于增强复合材料和合金；纳米力学控制着“智能”材料，能够从裂缝中自我修复；纳米生物力学可以直接研究人体最难以接近的部位等。随着纳米材料和纳米系统的快速发展，人们对精细空间和时间尺度的探索需求日益增加。本研究的主要目的是发展一种有效的多尺度建模方法，以实际模拟和分析纳米尺度问题，在广泛的长度和时间尺度上。该方法将用于研究金属晶格中的位错行为、新合金和添加元素对金属力学性能的影响、HAp-TZP（3Y）纳米复合材料的力学行为、缺陷碳纳米管的断裂以及用于纳米机电系统的多壁碳纳米管的动力学行为等问题。接下来，通过结合分子模拟和基于非线性连续介质力学的本构公式（包括聚合物材料的行为），将开发一种超弹性多尺度建模技术。该技术将用于预测聚碳酸酯（BPDA）和聚酰亚胺（APB）单体的弹性性能。最后研究了纳米颗粒对ZrO2/ sic纳米复合材料韧性的影响。总的来说，提出的研究旨在为纳米结构材料和系统的设计和制造提供有效的工程工具。这将反过来导致纳米技术领域的新理论发展和商业应用；从而为加拿大公司在全球快速增长的市场上生产创新纳米产品带来竞争优势。建议的研究重点与NSERC在2000-2002年GSC 13和新成立的加拿大国家纳米技术研究所的重新分配工作报告中确定的优先研究领域一致。

Nanotechnology has recently emerged as a rapidly growing field. The applications of nanoscience and nanotechnology are immense: nano-materials are used to strengthen composites and alloys; nano-mechanics govern 'smart' materials, capable of healing themselves from cracks; nano-biomechanics can be used to directly study the most inaccessible parts of the human body, etc. Along with rapid progress in nano-scale materials and systems, there is an increasing demand for probing into fine space and time scale. The main objective of this research is to develop an effective multiscale modeling method to practically simulate and analyze nano-scale problems, over a wide range of length and time scales. This method will be used to study problems, such as: behaviour of dislocations in metal crystal lattices, influence of new alloying and added elements on mechanical properties of metals, mechanical behaviour of HAp-TZP(3Y) nano-composite, fracture of defected carbon nanotubes, and dynamic behaviour of multi-wall carbon nanotubes used in nanoelectromechanical systems. Next by incorporating molecular simulations and a nonlinear continuum mechanics-based constitutive formulation that includes the behaviour of the polymer materials, a hyperelastic multiscale modeling technique will be developed. This technique will be employed to predict the elastic properties of polycarbonate (BPDA) and polyimide (APB) monomers. Finally the effects of nano-particles on the toughness of nano-composites, ZrO2/nano-SiC will be investigated. Overall, the proposed research aims to provide effective engineering tools for design and fabrication of nano-structured materials and systems. This will in turn lead to new theoretical developments and commercial applications in the nanotechnology area; and thus will bring competitive advantages to the Canadian companies in producing innovative nano-products in the very rapid growing market globally. The proposed research focus is in line with the priority research area as identified by NSERC in the 2000-2002 reallocations exercise report for GSC 13 and the newly established Canadian National Institute of Nanotechnology.