| 講演要旨： |
In this talk, several mechanics problems involuving multiscale
phenomena are discussed. After a brief overview on the multiscale
problems and on heir currently avaiable solution strategies, three
examples are presented. The first example is concerning the T-junction
formation of CNTs and the dislocation glide in silicon, in which
temporal multiscales are involuved. The energy barrier of T-junction
formation of a CNT and Peierls energy of dislocation in silicon are
calculated with the aid of the action-derived molecular dynamics
(ADMD). This demonstrates the effectiveness of the ADMD method in
finding the nimimum energy path and the energy barrier. The second
example is about the role of the microstructures or the
inhomogeneities in crack propagation, which involves the two length
scales of the inhomogenity and the structure at the continuum
level. The so-called variable-node elements are efficiently applied to
model the inhomogeneities and the crack tip, while the homogenization
technique is employed to cover the far-field region. This enables one
to find the crack path in an extremely straightforward manner in the
presence of the homogenities in continuum. The last example is the
concurrent multiscale simulation of CNTs' deformation and
fracture. The quasicontinuum, which is one of the most successful
methodologies for multiscale computing, is first extended for
application to curved crystalline structures like CNTs, and it is
concurrently hybridized to quantum mechanical computation to look into
the genuine fracture behavior of CNTs. |
