Solid-solid interaction issue using DEM in DesignSPHysics

[qoimzslm]

Hi everyone.

I am a beginner in using DualSPHysics with the GUI version and am currently working to incorporate DEM into my simulation to address solid-solid interactions. However, I am encountering some issues and would like to confirm whether my approach is correct.

From my understanding, there are two methods to implement DEM in DualSPHysics:

1. Using DCDEM:
   For this method, I configure the solid material properties, such as Young's modulus (E), Poisson's ratio (v), and the friction coefficient (Kfric), by selecting the material type for the solid body (e.g., concrete, glass, PVC, etc.). Additionally, in the execution parameters, I set the solid-solid interaction to "DEM." Does this process sufficiently enable the DCDEM approach in my simulation?
2. Using Project Chrono:
   For Project Chrono, I enable the "special" option in the pre-processing section and configure the Chrono settings. However, I am unclear about the meaning and configuration of the "Chrono Object" (e.g., geometry/original, invert, two faces). When I attempt to run the simulation with Project Chrono, a warning message appears (as shown in the attached figure). Are there any detailed manuals or tutorials available that explain how to properly implement DEM using Project Chrono?

I have tried applying both methods to my simulation, but the solid-solid interactions seem to be incorrect. Specifically, the two solid bodies appear to stick together upon contact, suggesting an issue with the contact forces. I try to use different materials as well for the solid body but it does not have that much influence.

I would greatly appreciate any guidance, resources, or suggestions to resolve this problem. Thank you.