Contact problems among viscoelastic materials in the multibody system is one of
the challenging topics in science and many engineering applications. We have developed an effective
simulation method of combining QDEM (Quadruple Discrete Element Method) for the deformation
analysis of structures with the DEM for the collisions among structures. However, it is
still difficult to reproduce surface topography of structures because particles only set on four
nodes of tetrahedrons in our current method. In this paper, QDEMSM (QDEM with Surface
Modeling) is newly developed. Point-polygon collisions and line-line collisions are effectively
coupled with QDEM. Our improved method was validated by several simulation results; domino
simulations using the 40 pieces of shogi (= Japanese chess) were successfully carried out. It
was also found the friction forces acted on the surface critically effected on the
propagation speeds of contact forces. In parallel computing, by applying the space-filling
curve to decomposition of the computational domain, we make it possible to contain the same
number of nodes in each decomposed domain. Our parallel
simulation code achieves a good weak scalability on the TSUBAME2.5 supercomputer
