Dear all,
I am working on UCS modeling with SPH particles. But the contact force decreased when particle spacing reaches 1 mm. I have tried different FORM and CSLH but all of them doesn't work.
Could some tell me how to handle this issue?
I’m going to preface this by addressing that I’m not familiar with this type of testing. What makes you think that there is an issue? Wouldn’t an increase in particle spacing lead to lower contact force?
@negativevolume Thanks for the response. As expected, the mesh sensitivity analysis should come to convergence when spacing is 1 mm (it has bee proved when using mat_003). For MAT_003, the result has came to the convergence when spacing is 1.25 mm. However, when I changed the material model to MAT_173, the finer mesh is needed to get convergence. Thus, I tested it with particle spacing of 1 mm, and this issue above occurred. I also tried the model of mat_003 with particle spacing is 1mm. It indicates that the model with particle spacing of 1 mm always shows a lower value than expected results.
Oh I see, you have actually reduced the distance between particles to 1. I didn’t realize that you were running a convergence study. Yeah that is strange that you would get a drop in force like that at a finer particle spacing. I can do some research but in the meantime you could try an even finer spacing just to see what happens. It could be a bug in the material.
@negativevolume I checked the model and there is an issue with contact settings. The issue is addressed by reducing the friction coefficient between plates and rock. I made a mistake of that set FC to a real value of 0.2. For the experimental result of UCS, the influence of friction has been included in it. Thus, the numerical model should minimize the influence of the friction if possible.
Ah that would make sense. So the dip in force has been addressed with the elimination of contact friction?
@negativevolume Yeah, I have ever worked on the parametric analysis of friction coefficient with FEM model. Tha peak force and failure mode are influenced by FC significantly.