Hi Ruochun, Thank you for your reply. In fact, I am puzzled that there is not any sentence in the Fracture-Box demo to declare the contact model between spheres and the compressing plate. So, how to declare the contact model, especially for the case in which there has been another contact model, such as the ForceModelWithFracture.cu?
Thank you, Weigang On Thursday, June 13, 2024 at 12:03:52 AM UTC+8 Ruochun Zhang wrote: > Hi Weigang, > > Note that in general, if you use a custom force model, then that model > alone is used, there is no fallback so I wouldn't call that anything has > "defaulted" to Hertz–Mindlin. Specific to the Fracture-Box demo, it's just > that the force model (ForceModelWithFracture.cu) is written in a way that > when the bond between two particles breaks, the "else" branch of that big > if statement is executed, and something similar to Hertz–Mindlin is > enforced. > > I said it's similar since it's not a pure spring–damper model now, it's a > spring–damper model with the resting location (zero-force location) being > the penetration depth the moment when the bond broke. This implementation > avoids a potential problem with a pure spring–damper model: Without the > adjusted resting location, a newly broken-away pair of particles would see > the bond suddenly gone but there were still left-over penetration, > therefore immediately pushing each other away with high velocity, resulting > in non-physical results. Shout-out to Bona for implementing this. > > Thank you! > Ruochun > > > On Wednesday, June 12, 2024 at 8:33:55 PM UTC+8 weigan...@gmail.com wrote: > >> Hi Ruochun, >> >> Thank you for your great work. The demo now is runs well. I have a >> question about the Fracture-Box demo. After the bond between two particles >> breaks, is it right that the contact model between them change defaultly >> from ForceModelWithFracture to Hertz–Mindlin model? >> >> Thank you, >> Weigang >> >> On Friday, May 31, 2024 at 8:05:24 PM UTC+8 Ruochun Zhang wrote: >> >>> Hi Weigang, >>> >>> The problem appears to be fixed now. Please pull the newest main branch >>> and try the fracture demo again. I suggest you do a clean rebuild from an >>> empty directory, because only a force model file is changed and if you just >>> "make", cmake probably thinks nothing needs to be done. Or you can simply >>> manually copy the modified cu file over to the appropriate location in the >>> build folder. >>> >>> The problem was that we left an uninitialized variable in the force >>> model file. On data center cards, the compiler zeros it out automatically, >>> but on consumer cards it does not. We therefore missed it initially. Should >>> be all good now. >>> >>> Thank you, >>> Ruochun >>> >>> >>> On Tue, May 28, 2024, 11:00 PM Ruochun Zhang <ruoc...@gmail.com> wrote: >>> >>>> Hi Weigang, >>>> >>>> It's not like recommending a card; rather, if you happen to have a data >>>> center card available (A100, A5000 etc.), you can circumvent this problem >>>> for now by using them. Otherwise, let's hope we find a solution very soon, >>>> or at least find a workaround. We'll keep you posted. >>>> >>>> Thank you, >>>> Ruochun >>>> >>>> On Monday, May 27, 2024 at 7:27:10 PM UTC+8 weigan...@gmail.com wrote: >>>> >>>>> Hi Ruochun, >>>>> >>>>> My card is indeed a gaming card NVIDIA GeForce RTX 2070 Super. Could >>>>> you recommend a card? >>>>> >>>>> Thanks, >>>>> Weigang >>>>> >>>>> On Saturday, May 25, 2024 at 10:44:17 PM UTC+8 Ruochun Zhang wrote: >>>>> >>>>>> Hi Weigang, >>>>>> >>>>>> I would like to answer Question 2 first. You can use variables >>>>>> *AOwnerFamily >>>>>> *and *BOwnerFamily *to refer to clump (or owner) A's and clump B's >>>>>> family numbers directly in the force model. So you can write *if >>>>>> *statements >>>>>> that treat each case accordingly. This is mentioned in the DEME paper: >>>>>> You >>>>>> can check out Table 2. >>>>>> >>>>>> For Question 1, the situation is more complicated. We are actually >>>>>> able to reproduce the problem you encountered (simulation freezing), but >>>>>> on >>>>>> consumer/gaming cards only. It runs perfectly on data center cards and >>>>>> that's what we used for generating this experiment, therefore it did not >>>>>> appear a problem for us. It's likely due to different GPU architectures >>>>>> running the same code differently, we'll try to find a solution and let >>>>>> you >>>>>> know in the following days, so stay tuned. By the way, you are using a >>>>>> gaming card to run the simulations, correct? >>>>>> >>>>>> Thank you, >>>>>> Ruochun >>>>>> >>>>>> On Friday, May 24, 2024 at 8:47:00 AM UTC+8 weigan...@gmail.com >>>>>> wrote: >>>>>> >>>>>>> Thank you for your reply! I have two questions about the demo >>>>>>> "DEMdemo-Fracture-Box". >>>>>>> >>>>>>> (1) After i have run this demo for one day, there is still nothing >>>>>>> outputed. Is it fact that the DEME will run a long time once a fracture >>>>>>> model is used? >>>>>>> >>>>>>> (2) How to tell DEME the contact force models between different >>>>>>> familys? I did not see any snippet which undertakes this work, although >>>>>>> the >>>>>>> demo has at least two kinds of contact force model. The question i >>>>>>> really >>>>>>> want to ask is that, if we have more than three familys in our model >>>>>>> and >>>>>>> there are more than two familys consist of spherical particles, how to >>>>>>> tell >>>>>>> DEME the contact force model between different familys, and tell DEME >>>>>>> the >>>>>>> contact force model between the particles of a family in the same time. >>>>>>> >>>>>>> Thank you, >>>>>>> Weigang >>>>>>> >>>>>>> On Thursday, May 23, 2024 at 10:10:14 PM UTC+8 Ruochun Zhang wrote: >>>>>>> >>>>>>>> No. That's because the *sphere components* in a clump are just >>>>>>>> shape representations, and they have no physics, only material >>>>>>>> properties. >>>>>>>> If they did have interaction with each other then every clump would've >>>>>>>> immediately exploded upon simulation starting. >>>>>>>> >>>>>>>> Thank you, >>>>>>>> Ruochun >>>>>>>> >>>>>>>> On Thursday, May 23, 2024 at 12:16:32 PM UTC+8 weigan...@gmail.com >>>>>>>> wrote: >>>>>>>> >>>>>>>>> Hi Ruochun, >>>>>>>>> >>>>>>>>> Thank you for your reply! I have a question about the clump. Do >>>>>>>>> the particles in a clump interact with each other via any force model? >>>>>>>>> >>>>>>>>> Thank you, >>>>>>>>> Weigang >>>>>>>>> >>>>>>>>> On Monday, May 20, 2024 at 10:26:03 PM UTC+8 Ruochun Zhang wrote: >>>>>>>>> >>>>>>>>>> Hi Weigang, >>>>>>>>>> >>>>>>>>>> Yes. Again, DEME only cares about the position and radius of >>>>>>>>>> the initial spheres, so you can supply it however you want. If you >>>>>>>>>> have a >>>>>>>>>> file that records this information using your own format, then the >>>>>>>>>> easiest >>>>>>>>>> thing is to have your own C++ or Python script that reads it into >>>>>>>>>> arrays >>>>>>>>>> and then feeds them to the solver. If your file shares the >>>>>>>>>> format with DEME's standard clump output file, or your file is >>>>>>>>>> simply the >>>>>>>>>> output of *WriteClumpFile*, then you can conveniently load clump >>>>>>>>>> positions and orientations by *ReadClumpXyzFromCsv *and >>>>>>>>>> *ReadClumpQuatFromCsv *(examples are in GRCPrep_Part1 and 2). >>>>>>>>>> Note that currently, sphere radius cannot be read from standard >>>>>>>>>> clump >>>>>>>>>> output files since it's part of the clump template information thus >>>>>>>>>> not in >>>>>>>>>> the clump output. >>>>>>>>>> >>>>>>>>>> Thank you, >>>>>>>>>> Ruochun >>>>>>>>>> >>>>>>>>>> On Monday, May 20, 2024 at 12:56:56 PM UTC+8 weigan...@gmail.com >>>>>>>>>> wrote: >>>>>>>>>> >>>>>>>>>>> Hi Everyone, >>>>>>>>>>> >>>>>>>>>>> I would like to generate a block which consists of a assembly >>>>>>>>>>> spheres. Is it possible to generate the block by other code, and >>>>>>>>>>> then load >>>>>>>>>>> it into DEM-Engine via a file containg the informations (such as >>>>>>>>>>> position >>>>>>>>>>> and radius) of the spheres? >>>>>>>>>>> >>>>>>>>>>> Thank you, >>>>>>>>>>> Weigang >>>>>>>>>>> >>>>>>>>>> -- >>>> 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 projectchron...@googlegroups.com. >>>> To view this discussion on the web visit >>>> https://groups.google.com/d/msgid/projectchrono/1910af21-d1e3-43dd-a779-0c229e6150a6n%40googlegroups.com >>>> >>>> <https://groups.google.com/d/msgid/projectchrono/1910af21-d1e3-43dd-a779-0c229e6150a6n%40googlegroups.com?utm_medium=email&utm_source=footer> >>>> . >>>> >>> -- You received this message because you are subscribed to the Google Groups "ProjectChrono" group. 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