准连续介质方法及其应用

QUASICONTINUUM METHOD AND ITS APPLICATIONS

介绍原子和连续介质耦合的多尺度模拟中的一个重要方法——准连续介质方法。阐述与该方法相关的原子模拟方法和有限元方法,针对在原子区/连续介质区耦合时出现的匹配问题,讨论在非局部原子区和局部的连续区过渡中交接面的处理,即在两种区域采用不同的权重计算系统的能量。对于模拟过程中材料微观变形不断变化的情况,结合自适应网格技术,确保在需要时保持原子区的全部细节,而在连续介质区则相对粗化。最后,介绍准连续介质方法在晶界变形与断裂、纳米压痕和位错相互作用等方面的一些应用和发展,并对该方法面临的问题和发展趋势做了展望。

One of the significant methods of multi-scale computer simulation named quasicontinuum method which is a mixed atomistic-continuum formulation is reviewed. The computational modeling related to atomistic/continuum coupling is introduced on the energetics of atomistic and continuum concepts and finite element methods. The coupled method with the disposal of the interface between the non-local field and the local field is discussed, which is to adopt different weight factors to calculate the energy of the system in the two fields. Automatic mesh adaption is combined to ensure that full atomistic detail is retained in regions of the problem where it is required while continuum assumptions reduce the computational demand elsewhere. Recent advances and some applications of grain boundary deformation and fracture, nano-indentation and the interaction of dislocations are noted, and the further study and trends of this field are outlined.