  Capturing the interaction between objects that have an extreme difference in
Young s modulus or geometrical scale is a highly challenging topic for
numerical simulation. One of the fundamental questions is how to build an
accurate multi-scale method with optimal computational efficiency. In this
work, we develop a material-point-spheropolygon discrete element method
(MPM-SDEM). Our approach fully couples the material point method (MPM) and the
spheropolygon discrete element method (SDEM) through the exchange of contact
force information. It combines the advantage of MPM for accurately simulating
elastoplastic continuum materials and the high efficiency of DEM for
calculating the Newtonian dynamics of discrete near-rigid objects. The MPM-SDEM
framework is demonstrated with an explicit time integration scheme. Its
accuracy and efficiency are further analysed against the analytical and
experimental data. Results demonstrate this method could accurately capture the
contact force and momentum exchange between materials while maintaining
favourable computational stability and efficiency. Our framework exhibits great
potential in the analysis of multi-scale, multi-physics phenomena
