| Recent developments in methods for modeling complex materials and behavior using multiscale atomistic-continuum techniques are presented. The primary focus is the development of a new adaptive method, dubbed the Dynamically Evolving Bridging Domain Method (DEBDM), for modeling propagating and interacting material defects such as dislocations and nano-sized cracks. The DEBDM is a computationally efficient concurrent atomistic-to-continuum approach based on the Bridging Domain Method, where the atomic domain dynamically adapts to encompass evolving defects, maintaining atomic resolution only where necessary. As part of the DEBDM, new adaptive algorithms have been developed to fine-grain portions of the continuum to MD in order to expand the MD domain, and additionally to coarse-grain MD subdomains (including discontinuities) to the continuum using FEM/XFEM. Since atomic degrees of freedom are maintained only where needed for each timestep, the solution retains the advantages of multiscale modeling, with a reduced computational cost compared to other non-adaptive multiscale methods. Several examples of interacting dislocations and nano-cracks are presented to demonstrate the flexibility and efficiency of the method.;Additional research is currently underway for the multiscale atomistic-continuum modeling of complex polymer materials. Polymer materials are extremely difficult to couple across these scales due to highly localized inhomogeneous phenomena that occurs amongst the polymer chains as they deform. Through a macroscopic velocity coupling technique based on the BDM, we are able to overcome some of the difficulties which hinder research in this area. This method is currently referred to as the Polymer BDM, or PBDM. |
