Abstract
An atomistic calculation makes it possible to evaluate the strength of coating, which feature is affected by nano structure such as nanopore. However, because of the restriction of the computational resources, the atomistic calculation has the limitation of analytical region to nano meter order. To compensate this situation, a multiscale analysis from atomistic to continuum is introduced. The quasicontinuum model has been developed for the multiscale modeling to enable as seamless description of solid mechanical behavior from the atomistic to the continuum scale. In the quasicontinuum method, system under interest is modeled by the distributed atoms, and discretized by finite element meshes, and their positions are prescribed by means of the nodal displacements related to the conventional shape functions. Sum of the interatomic potential, which is determined by the positions of the atoms, is equivalent to the total energy of the system. The total energy of the system is determined by the nodal displacements and minimized through the variational method of the conventional finite element formulation. In this method, the total degrees of freedom are largely reduced in comparison to the molecular dynamics. In this paper, a fundamental research to utilize the quasicontinuum model in two dimensional atomistic fracture problems is carried out. We find out the adequate discretization manner around a crack tip, and we conclude that the finest elements should be extended to at least 15 atoms distance from the crack tip.
