Hello Mike, I was wondering if you had the chance to look into our issue since last week ? Thanks a lot, All the best, Solenne
Le jeudi 9 janvier 2025 à 09:02:10 UTC+1, SoMdt a écrit : > Mike, > > Here are some snapshots from Abaqus. In the second case, the surface area > indeed changes significantly like an inflating baloon. I also added an > image overlaying Abaqus simulation result (in green) and Chrono simulation > result (in white) on the large deformation case. > > Moreover, I tried calling element->SetDimensions() before each iteration > to update the element's dimensions but it did not change anything. > Thanks a lot for the time you can make to dive into this. > Solenne > > > [image: Cylinder_SmallDefs_MaxPrincStrain.png][image: > Cylinder_SmallDefs_Disp.png] > [image: Cylinder_largeDefs_MaxPrincStrain.png][image: > Cylinder_SmallDefs_Disp.png][image: ChronoVSAbauqs.png] > > > Le jeudi 9 janvier 2025 à 02:58:46 UTC+1, Mike Taylor a écrit : > >> Solenne, >> >> Best case, it will likely be a couple of days before I can dive deeper >> into the files you sent. >> >> Looking at your latest message, I was wondering what kind of strains you >> are seeing in each of these models with ABAQUS. Is your enclosed volume >> changing significantly, similar to inflating a balloon with the large >> pressure and not significantly with the lower pressure? If so, that would >> mean that the surface area of the elements significantly changed with the >> second pressure, which might narrow down where I need to start looking. >> >> Could you share a few images from ABAQUS of the undeformed vs. deformed >> shape (true scale, not exaggerated) for each of the two pressures for >> additional visual context. Maximum principal strain contours from ABAQUS >> might be helpful as well. >> >> Best Regards, >> Mike >> >> On Wednesday, January 8, 2025 at 3:31:55 AM UTC-6 SoMdt wrote: >> >>> Dear Mike, >>> >>> >>> >>> Thanks you very much for your answer, here are our latest advancement on >>> the topic. >>> >>> To answer in the order : >>> >>> - I tried both non linear static and dynamic tests and obtained the >>> same results >>> - I specifically launched a simulation with a very fine mesh + very >>> small timestep, but this did not improve the results. >>> - Eventually, we implemented ANCF_3833 elements, but the result is >>> the same as 3423 and Reissner. >>> - I also tested using SetStiff(true) for the pressure load but the >>> results are the same. >>> >>> >>> >>> I am thinking we might have missed something in the implementation. >>> >>> >>> >>> To complete my message, here are all the results for the maximum >>> displacement in mm, both in Abaqus and in Chrono for two different values >>> of pressure (p=0.001MPa -> small deformation, p=0.03MPa -> large >>> deformation): >>> *Abaqus * p=0.001 : d= >>> 1.51e-2 p=0.03 : d= 7.81e-1 >>> *Chrono - Shell Reissner * p=0.001 : d= 1.46e-2 >>> p=0.03 : d= 4.18e-1 >>> *Chrono - ShelANCF_3423 * p=0.001 : d= 144e-2 p=0.03 >>> : d= 3.73e-1 >>> *Chrono - ShellANCF_3833* p=0.001 : d= 1.42e-2 p=0.03 >>> : d= 3.73e-1 >>> >>> >>> >>> I join you all the simulation files (cpp + mesh + nodesets for boundary >>> conditions). If you have time to look into it, I would be immensely >>> grateful: we are currently completely blocked in our project due to this >>> issue. >>> >>> Best regards, >>> >>> Solenne >>> >>> >>> Le jeudi 12 décembre 2024 à 23:51:13 UTC+1, Mike Taylor a écrit : >>> >>>> Solenne, >>>> >>>> I'm most familiar with the ANCF elements. The ANCF formulation >>>> supports both geometric and material non-linearities. Currently most of >>>> the ANCF elements in Chrono are formulated with only a linear viscoelastic >>>> material, but they do inherently support moderately large deformations >>>> (i.e. large angle bending, but not plastic like flows.) >>>> >>>> Here are a few thoughts on things to try: >>>> >>>> If you've only tried to run a static analysis, you might want to >>>> try running a dynamic analysis with a slowly applied load with a >>>> relatively >>>> large amount of damping to dynamically settle to the "static" solution? >>>> >>>> If you are running a static analysis, are you running the linear static >>>> or nonlinear static analysis version? If you are using the nonlinear >>>> static analysis, what argument are you giving that function? >>>> >>>> If you haven't already examined refining your mesh (using more >>>> elements), you might want to give that a try as well. >>>> >>>> Finally, the ANCF Shell 3423 element has a relatively low order >>>> (linear) interpolation function. You could also try an element with a >>>> richer/higher order interpolation function like the >>>> "ChElementShellANCF_3833"element. >>>> >>>> Best Regards, >>>> >>>> Mike Taylor >>>> >>>> On Tuesday, December 10, 2024 at 10:26:15 AM UTC-6 SoMdt wrote: >>>> >>>>> Hello, >>>>> >>>>> I am implementing a simple test of a cylinder with fixed extremities >>>>> under pressure (length of 42 mm, radius of 2.5 mm and thickness of 0.6 >>>>> mm). >>>>> Material has a Young's modulus of 0.6 MPa and nu=0.45. >>>>> I tested ShellBST, ShellReissner and ShellANCF4234 in chrono and >>>>> compared the results with Abaqus. >>>>> >>>>> With a pressure of 0.001 MPa, the results are the same as Abaqus. >>>>> However, when increasing the pressure to 0.03 MPa, the deformation of the >>>>> cylinder is roughly twice lower in chrono than in Abaqus (results are in >>>>> the same magnitude for all 3 shell elements). >>>>> >>>>> To completed the analysis, in Abaqus, when setting the NLGEOM >>>>> parameter to NO, the deformation goes down to the range of chrono >>>>> deformation. >>>>> >>>>> My question then : are there shelle elements able to consider large >>>>> deformations ? Did I forget a hidden parameter somewhere ? >>>>> >>>>> Thanks a lot for you help, >>>>> Solenne >>>>> >>>> -- 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 visit https://groups.google.com/d/msgid/projectchrono/44e43cef-2393-4d9b-bff8-25328ed6bf8an%40googlegroups.com.
