Multiresolution, Coarse-Grained Modeling of 3D Dislocation Nucleation and Migration

三维位错成核和迁移的多分辨率、粗粒度建模[j]: David L. McDowell， Co-PI: Ting zhun支持抗断裂材料设计的下一代模型必须直接包含与纳米级原子间键和界面结构相关的信息。挑战在于开发一种方法，既能处理如此小尺度的行为，又能解释结构应用（如汽车、飞机、网球拍等）中更高尺度的平均行为方面。该项目将通过在纳米尺度上使用原子学（分子动力学）在裂纹尖端附近或在长范围场的界面上分析缺陷来解决行为问题，这些缺陷平均影响大量原子，以实现所谓的？粗粒?描述。通过这种方式，模拟可以在足够高的长度和时间尺度上进行，以提供有关结构行为的有意义的信息，同时以原子尺度分辨率处理界面的作用。该研究有望对调整晶界组织和细尺度组织的能力产生实质性影响，从而提高金属合金的抗疲劳和抗断裂能力。疲劳是金属在循环载荷下的一种失效模式，它是造成代价高昂的故障的原因，如公路桥梁、飞机尾部、发动机部件、铁路脱轨以及许多其他例子。通过开发更多的预测工具来解决原子尺度和多晶颗粒尺度（通常为五个数量级）之间建模和仿真工具的巨大差距，从更轻量化和耐用的材料中获得的节能和安全方面的社会效益可以是实质性的。研究成果将整合到PI和co-PI教授的计算材料科学本科课程以及材料缺陷和力学性能研究生课程中，加速本项目开发的技术的应用。

CMMI 0758265Multiresolution, Coarse-Grained Modeling of 3D Dislocation Nucleation and MigrationPI: David L. McDowell, Co-PI: Ting ZhuNext generation models to support design of fracture-resistant materials must directly incorporate information related to interatomic bonding and structure of interfaces at nanoscales. The challenge is to develop methods that can address behavior at such small scales yet still account for aspects of average behavior at much higher length scales in structural applications such as automobiles, aircraft, tennis rackets, and so forth. This project will address behavior by linking defects analyzed at the nanoscale using atomistics (molecular dynamics) near the tips of cracks or at interfaces with long range fields that average effects of large numbers of atoms to achieve a so-called ?coarse grain? description. In this way, simulations can be undertaken at high enough length and time scales to provide meaningful information regarding behavior of structures, while the role of interfaces is treated with atomic-scale resolution.This research is expected to substantially impact the ability to tailor the structure of grain boundaries and fine scale microstructure to affect improved fatigue and fracture resistance of metal alloys. Fatigue is a failure mode in metals subjected to cyclic loading that is responsible for costly failures such as highway bridges, airplane tail sections, engine components, railway derailments, and many other examples. By developing more predictive tools to address the large gap in modeling and simulation tools between atomic scales and scales of grains in polycrystals (typically five orders of magnitude), the societal benefits in terms of energy savings and safety derived from more lightweight and durable materials can be substantial. Research results will be integrated into both an undergraduate course in computational materials science as well as graduate courses in defects and mechanical properties of materials taught by the PI and co-PI, accelerating the application of the technology developed in this project.