Hi Mike Taylor, Thank you for the reply. The problem is that you seem to have to know the dimensions of the elements. If I take, for instance, the "demo_FEA_hexaANCF_3813.cpp" demo and don't specify the InertFlexVec in line 167, the simulation starts, but nothing happens.
If I use meshing software to create a hexahedral mesh, the elements don't necessarily need to have the same edge lengths per dimension. Thus, I can't set the InertFlexVec vector, can I? Kind regards, Paul Mike Taylor schrieb am Dienstag, 21. Mai 2024 um 04:32:27 UTC+2: > Paul, > > The "ChElementHexaANCF_3813" element is really a traditional 8 node > hexahedral element (nodes with only position coordinates). If you Google > "sphere hexahedral mesh" and look at the images, you'll see some approaches > to meshing a sphere with only hexahedral elements. If you are trying to > mesh an ellipsoid, one approach would be to start with the hexahedral mesh > of a sphere and then scale it along the three axes to match your > ellipsoid's geometry. A FEA meshing program might help here depending on > how fine a mesh you need. > > As for other "solid" elements, there is code for the > ChElementHexaANCF_3843 element (ChElementHexaANCF_3843_MR_Damp) that > implements a 2-term Mooney-Rivlin material law with a non-linear single > coefficient Kelvin-Voigt damping model in the fork I used for my PhD thesis > (https://github.com/taylome/chrono/tree/thesis/hyperelastics). This is > based on Chrono 7 and the code requires updates to use it in Chrono 9. > Also note that the ChElementHexaANCF_3843 element uses 12 coordinates per > node, 3 position coordinates and 3 position vector gradient coordinate > sets. The position vector gradient coordinates can make the element a > little harder to use from a meshing perspective. Long term, the goal is to > merge the hyperelastic code developed in this fork into the main Chrono > repository after some more additional development. > > Best Regards, > > Mike Taylor > On Friday, May 3, 2024 at 5:07:33 AM UTC-5 [email protected] wrote: > >> Hello everyone, >> >> I want to include an ellipsoidal geometry in my model and simulate it >> with finite elements. My problem now is that I want to use a hyperelastic >> material model (e.g. Mooney-Rivlin), and only the >> "ChElementHexaANCF_3813" element implements that. As I take it from the >> examples, you need a structured mesh where the hexahedral elements have >> known dimensions, which is difficult for an ellipsoid. >> >> I'm quite new to FEA and have only the following ideas: >> >> - divide the geometry into multiple simpler boxes (don't know how to do >> this automatically yet) >> >> - add the hyperelastic material model to the other elements >> >> - use an external FEM solver and implement an interface to Chrono (can't >> estimate how difficult this would be) >> >> Maybe you can help me find the best option. >> >> Thank you, and kind regards, >> >> Paul >> > -- 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/a8526325-4c71-4a45-b4a0-d1af396beaf7n%40googlegroups.com.
