Hi Giovanni, Can I also have the two mesh files you are using to test it?
Before I test, I can see the particles you are using are small (0.5mm), and the mesh is stiff and has a high Coefficient of Restitution. This makes contacts with this mesh challenging to resolve and I doubt if 5e-6 as the step size is enough. About the message you got, that should be a warning, but it is a warning when the physics is getting bad so I guess it's close to an error (you can still turn it off by setting the *Verbosity *from STEP_METRIC to INFO), and this could tie back to my suspicion that the time step size is far from enough. But if I can get the mesh, I can say for sure. Ruochun On Wednesday, July 19, 2023 at 4:37:13 PM UTC-5 Giovanni Bianchi wrote: > [image: Immagine 19-07-23 - 23.34.jpeg][image: Immagine 19-07-23 - > 23.34.jpeg][image: Immagine 19-07-23 - 23.33.jpeg]Thanks, Rouchun, > > I link here the code that I am using and the graphic output I get from the > simulation. > > I don't know the exact Young modulus of the material I am using, and I am > testing different values. I get this problem of particles passing through > the mesh only for low values of E; instead, for high values, the simulation > crashes, giving the error: " N contacts were active at time xxx on dT, but > they are not detected on kT, therefore being removed unexpectedly!". > > > > Giovanni > > Il giorno mercoledì 19 luglio 2023 alle 23:14:13 UTC+2 Ruochun Zhang ha > scritto: > >> Hi Giovanni, >> >> It's hard to say without seeing the script and the rendering. Since you >> are doing a compression test and DEM is penalty/penetration based, it could >> be just that there is so much compression that the penetration is too big, >> so the particles appear to be phasing through the mesh (note that if *E* >> is low and the particles are relatively large, then having visible >> phasing-through can be normal). It could also be that the particles are >> somehow under a large load (say, being compressed by an invisible boundary >> without the user's knowledge) and it forces the particles through the mesh. >> Or maybe the mesh is not oriented correctly (triangle facet normal >> direction) so the particles approach it from the inner side, and then phase >> through. >> >> If you put here a rendering of the problem, and if you can, show the >> script you are using, it should be easy to diagnose. >> >> Thank you, >> Ruochun >> >> On Wednesday, July 19, 2023 at 3:53:15 PM UTC-5 Giovanni Bianchi wrote: >> >>> Hello everyone! >>> >>> I am simulating the compression of a granular material with DEM-Engine, >>> and in some cases it seems that some particles pass through the mesh >>> boundary. >>> I adapted the mixer demo to my case without changing anything in the >>> contact detection parameters. >>> >>> What am I doing wrong? >>> >>> Giovanni >>> >> -- You received this message because you are subscribed to the Google Groups "ProjectChrono" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/projectchrono/4c7fb82e-4052-43d6-b218-c25525c5dbcfn%40googlegroups.com.
