Based on dynamic relaxation of discrete element method (DEM)

a control displacement solution for displacement integral is proposed to solve the problem caused by unreasonable time-step interval impacting on the stability of the result. The time-step interval is determined by pre-calculating the displacements of the discrete blocks. The proposed solution not only solves the problem of excessive overlap between blocks

but also improves the precision of displacement integral and calculating efficiency. The relevant program is developed with its flow chart

and a typical example is given in this paper.