1. open DEM-FEM.inp file in ABAQUS
2. Mesh the part to be converted to particles using standard, linear, hex elements. Set the approximate global size to the desired particle diameter. Ensure the element type is C3D8R. 
3. Create interaction properties for particle-to-particle contact (P11) and particle-to-boundary contact (P12).
4. Create different surfaces for each part the particles will come into contact with within the assembly, then save.
5. open the input file in .txt, change this element type assignment to PD3D, the element type for particles.
6. Edit the input file, Before *End Part for the metal pile, there will be an *Elset section with three numbers separated by commas and a *Nset section with three other numbers.
7. The following lines will need
to be input for each step, at the end of the step and before **Boundary Conditions.
----------------------------------------
*Contact
*Contact controls assignment, rotational terms=STRUCTURAL
*Contact Inclusions
DEM1,DEM1
DEM1, Master2
DEM1, Master1
*Contact Property Assignment
DEM1,DEM1,P11
DEM1,Master2,P12
DEM1,Master1,P12
----------------------------------------
Under *Contact Inclusions, include each pair of interacting surfaces. For this example,
DEM1,DEM1 are the particle-to-particle interactions and DEM1,Master1 and DEM1,Master2 are
particle-to-boundary interactions.
8. load the input file into Abaqus.