My own DEM(Discrete Element Method) program's solution for static problem seems strange.

I use my program to calculate the displacement of a cantilever under static pressure:

1. it seems my program shows convergence for static problem as the mesh gets denser. As the mesh grows denser(that means the particle becomes smaller), the displacement(of y direction)  of the free tip becomes smaller.

2. if the particle is big, the displacement of the free tip is greater than the theoretical solution, but if the particle is small enough,  the displacement gradully becomes smaller than the theoretical solution.

MechSys is a C++ library to help the implementation of software for Mechanical Systems. There are 4 main modules in the library: