Numerical study and multi-objective optimization of flexible screening process of flip-flow screen: A DEM-FEM approach

•A numerical model of the flexible screening process was established.•The thick material layer working condition of flip-flow screen was studied.•The interact between flexible screen surface and particles was studied.•The influence of operation parameters of on screening effect of VFFS was analyzed.•It’s more need to achieve equal thickness screening of flip-flow screen.