# PrePoMax in the RR3 Wind-Turbine Tower Benchmark (Sadowski Round Robin 2024–2025) – Results & Observations **URL:** \ **Category:** Tips & Tricks\ **Created:** [November 3, 2025, 9:44am UTC](https://prepomax.discourse.group/t/prepomax-in-the-rr3-wind-turbine-tower-benchmark-sadowski-round-robin-2024-2025-results-observations/3049 "2025-11-03T09:44:04Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![hnrwagner](https://avatars.discourse-cdn.com/v4/letter/h/e8c25b/32.png) [@hnrwagner](https://prepomax.discourse.group/u/hnrwagner)\ **Post date:** [November 8, 2025, 7:51am UTC](https://prepomax.discourse.group/t/prepomax-in-the-rr3-wind-turbine-tower-benchmark-sadowski-round-robin-2024-2025-results-observations/3049/21 "2025-11-08T07:51:24Z")
GMNA reference solution: LPF = 1.2. Regarding the imperfection definition, there are no conclusive definitions for the amplitude, but the GMNIA reference LPF is about 1.0. Can you share your model, the \*.inp would be enough. ---
**Author:** ![FEAnalyst](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/feanalyst/32/688_2.png) [@FEAnalyst](https://prepomax.discourse.group/u/FEAnalyst)\ **Post date:** [November 8, 2025, 8:48am UTC](https://prepomax.discourse.group/t/prepomax-in-the-rr3-wind-turbine-tower-benchmark-sadowski-round-robin-2024-2025-results-observations/3049/22 "2025-11-08T08:48:18Z")
> [@ANYS](#): > > By other hand, we recently found a case (Colliding tubes) in which the convergence was failing due to the set up in the support, far away from where every body was searching the issue. Yeah, this one (it was necessary to release rotational DOFs to make contact converge even though it worked in older releases of CalculiX): [Contact of two shell pipes - no convergence in newer ccx releases - Advanced features - CalculiX (official versions are on www.calculix.de, the official GitHub repository is at https://github.com/Dhondtguido/CalculiX).](https://calculix.discourse.group/t/contact-of-two-shell-pipes-no-convergence-in-newer-ccx-releases/2865) > [@ANYS](#): > > For some reason, I cannot open files from other users. There is always a warning regarding corruption or incompatible version. I often have warnings that someone’s file was created in another version (fortunately, it says which one) and either it doesn’t open at all if the versions is very different, opens with some issues due to incompatiboe features or just opens fully. Maybe I had a case that the file was created in the same version I was using to open it (Matej still provides old versions so you can often adapt to that) and there was still an issue, but it’s very rare. > [@ANYS](#): > > @FEAnalyst – in a previous post I reported a similar issue with one of your files. You changed something, resent the file, and suddenly I was able to open it. Do you recall what modification you applied? Was it a long time ago ? ---
**Author:** ![ANYS](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/anys/32/7737_2.png) [@ANYS](https://prepomax.discourse.group/u/ANYS)\ **Post date:** [November 8, 2025, 9:44am UTC](https://prepomax.discourse.group/t/prepomax-in-the-rr3-wind-turbine-tower-benchmark-sadowski-round-robin-2024-2025-results-observations/3049/23 "2025-11-08T09:44:30Z")
> [@hnrwagner](#): > > GMNA reference solution: LPF = 1.2. GMNA=1.17. I can only estimate it measuring in a pdf. GMNA is one of the values on which there was most agreement among the different analysts. ![imagen](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/1/1e8fb857bf89a11e3c48fb802ee7c3ea5088b5cd.png) > [@FEAnalyst](#): > > Was it a long time ago ? I can’t find it. ---
**Author:** ![ANYS](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/anys/32/7737_2.png) [@ANYS](https://prepomax.discourse.group/u/ANYS)\ **Post date:** [November 8, 2025, 10:23am UTC](https://prepomax.discourse.group/t/prepomax-in-the-rr3-wind-turbine-tower-benchmark-sadowski-round-robin-2024-2025-results-observations/3049/24 "2025-11-08T10:23:13Z")
> [@hnrwagner](#): > > Regarding the imperfection definition, there are no conclusive definitions for the amplitude I think there are. > [@hnrwagner](#): > > Can you share your model, the \*.inp I hope you could still review your submission and help CCX/Prepomax receive a fair overall review in the RR3 Tower Finite Element Benchmark (Part 3 – Software Survey). The transfer includes the GMNA setup; MNA can be obtained by simply removing the _NLGEOM_ option. Will be available three days. > **[Tower\_GMNA\_Prep.inp](https://wetransfer.com/downloads/939c8403595c068ee548da549520825f20251108101638/ace59e?t_exp=1762856198&t_lsid=be983e78-9954-44e6-b9ab-550510bbe6e0&t_network=link&t_s=download_link&t_ts=1762596998)** > > 1 file sent via WeTransfer, the simplest way to send your files around the world EDITED: can–\> Could. Sorry about my poor English. I forgot can is rude 😬 . ---
**Author:** ![hnrwagner](https://avatars.discourse-cdn.com/v4/letter/h/e8c25b/32.png) [@hnrwagner](https://prepomax.discourse.group/u/hnrwagner)\ **Post date:** [November 9, 2025, 8:29am UTC](https://prepomax.discourse.group/t/prepomax-in-the-rr3-wind-turbine-tower-benchmark-sadowski-round-robin-2024-2025-results-observations/3049/25 "2025-11-09T08:29:55Z")
![Bild2](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/7/79cb618f352a658d68cbacae54b341eaba1184b5.jpeg) crazy, now it also works on my full 3D Solid model, I just removed the rigid body constraint from the bottom, thats it nothing else, I will update my Report on the RR3 and inform Dr. Sadowski that I need a few more days for my Report. Will also upload a video regarding this analysis to my Youtube Channel. ---
**Author:** ![FEAnalyst](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/feanalyst/32/688_2.png) [@FEAnalyst](https://prepomax.discourse.group/u/FEAnalyst)\ **Post date:** [November 9, 2025, 9:47am UTC](https://prepomax.discourse.group/t/prepomax-in-the-rr3-wind-turbine-tower-benchmark-sadowski-round-robin-2024-2025-results-observations/3049/26 "2025-11-09T09:47:36Z")
> [@hnrwagner](#): > > I just removed the rigid body constraint from the bottom, thats it nothing else Yeah, it’s just that nasty “rigid body + Nlgeom + shells = non-convergence” limitation of CalculiX. It’s explained by the CalculiX dev here: [Rigid-body constraint convergance problems - #25 by dhondt - CalculiX (official versions are on www.calculix.de, the official GitHub repository is at https://github.com/Dhondtguido/CalculiX).](https://calculix.discourse.group/t/rigid-body-constraint-convergance-problems/369/25) Here you can find a list of various CalculiX limitations with workarounds: [Known CalculiX limitations](https://prepomax.discourse.group/t/known-calculix-limitations/3050) ---
**Author:** ![lucas\_bueno](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/lucas_bueno/32/1168_2.png) [@lucas\_bueno](https://prepomax.discourse.group/u/lucas_bueno)\ **Post date:** [November 9, 2025, 12:49pm UTC](https://prepomax.discourse.group/t/prepomax-in-the-rr3-wind-turbine-tower-benchmark-sadowski-round-robin-2024-2025-results-observations/3049/27 "2025-11-09T12:49:21Z")
Ooh, I missed the timing on this one! Congratulations everyone involved, it is always nice to see benchmarks being succesfully tested and even better when CCX gives good results. > [@ANYS](#): > > I can only estimate it measuring in a pdf When I was using data from old NACA reports, I discovered a good tool to extract more or less precise values from printed plots: [PlotDigitizer Online App](https://plotdigitizer.com/app). Might be useful 😀 Best regards, Lucas ---
**Author:** ![FEAnalyst](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/feanalyst/32/688_2.png) [@FEAnalyst](https://prepomax.discourse.group/u/FEAnalyst)\ **Post date:** [November 9, 2025, 12:56pm UTC](https://prepomax.discourse.group/t/prepomax-in-the-rr3-wind-turbine-tower-benchmark-sadowski-round-robin-2024-2025-results-observations/3049/28 "2025-11-09T12:56:12Z")
> [@lucas\_bueno](#): > > When I was using data from old NACA reports, I discovered a good tool to extract more or less precise values from printed plots: [PlotDigitizer Online App](https://plotdigitizer.com/app). Might be useful 😀 Personally, I prefer desktop apps, and so I use open-source Plot Digitizer for that: [https://plotdigitizer.sourceforge.net/](https://plotdigitizer.sourceforge.net/) ---
**Author:** ![ANYS](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/anys/32/7737_2.png) [@ANYS](https://prepomax.discourse.group/u/ANYS)\ **Post date:** [November 9, 2025, 10:13pm UTC](https://prepomax.discourse.group/t/prepomax-in-the-rr3-wind-turbine-tower-benchmark-sadowski-round-robin-2024-2025-results-observations/3049/29 "2025-11-09T22:13:27Z")
My GMNIA it’s LPF=0.92 ![imagen](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/3/303988d992c51873947b3b0529fa2ff90e59ab9c.jpeg) ---
**Author:** ![AsuraEquation](https://avatars.discourse-cdn.com/v4/letter/a/6de8d8/32.png) [@AsuraEquation](https://prepomax.discourse.group/u/AsuraEquation)\ **Post date:** [November 10, 2025, 9:42am UTC](https://prepomax.discourse.group/t/prepomax-in-the-rr3-wind-turbine-tower-benchmark-sadowski-round-robin-2024-2025-results-observations/3049/30 "2025-11-10T09:42:55Z")
This discussion is really very interesting. I have just finished a wonderful course on GMNIA and seeing that PrePoMax can also perform these analyses (with a few minor adjustments and limitations, of course) really surprised me. Let’s hope that the arch-length method will also be introduced. I would also be curious to know why Calculix does not support 2D finite elements (I do not consider Calculix’s extrusion to be a solution, as I use 1D and 2D elements to reduce computation and therefore I lose this advantage with extrusion). I find it really “ peculiar” that I can perform crazy analyses (GMNIA, contact wear, Herz, fatigue, snap-fit, hyper-elastic material, etc.), but I have not implemented 1D and 2D elements, which are the most “dumb” finite elements to use. Anyway, I am joining the discussion to find out what imperfection value was used (and what deformation was used) and to congratulate you all on the results obtained. It was nice to see how you got around the problems with Calculix to achieve such a good result. ---
**Author:** ![FEAnalyst](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/feanalyst/32/688_2.png) [@FEAnalyst](https://prepomax.discourse.group/u/FEAnalyst)\ **Post date:** [November 10, 2025, 9:59am UTC](https://prepomax.discourse.group/t/prepomax-in-the-rr3-wind-turbine-tower-benchmark-sadowski-round-robin-2024-2025-results-observations/3049/31 "2025-11-10T09:59:03Z")
> [@AsuraEquation](#): > > I have just finished a wonderful course on GMNIA By Enterfea ? > [@AsuraEquation](#): > > Let’s hope that the arch-length method will also be introduced. This was planned by CalculiX dev a few years ago (it’s still mentioned here: [CalculiX: Preview of scheduled finite element capabilities of CalculiX](http://dhondt.de/pre_calc.htm)), but no sign of it yet. > [@AsuraEquation](#): > > I would also be curious to know why Calculix does not support 2D finite elements (I do not consider Calculix’s extrusion to be a solution, as I use 1D and 2D elements to reduce computation and therefore I lose this advantage with extrusion). Even though they are internally converted to a single layer of equivalent wedge or hex solid elements, they are still helpful. They provide sufficient accuracy in many cases and are easy to define. Their main disadvantage is that the knot generation is nonlinear and may cause nonconvergence in combination with some other nonlinearities and constraints. In fact, CalculiX has one true shell user element, but it’s very limited. Hopefully, more such elements will be added in the future. ---
**Author:** ![TKemeny86](https://avatars.discourse-cdn.com/v4/letter/t/58f4c7/32.png) [@TKemeny86](https://prepomax.discourse.group/u/TKemeny86)\ **Post date:** [November 10, 2025, 10:00am UTC](https://prepomax.discourse.group/t/prepomax-in-the-rr3-wind-turbine-tower-benchmark-sadowski-round-robin-2024-2025-results-observations/3049/32 "2025-11-10T10:00:39Z")
This whole topic could be a nice tutorial-subject… ---
**Author:** ![hnrwagner](https://avatars.discourse-cdn.com/v4/letter/h/e8c25b/32.png) [@hnrwagner](https://prepomax.discourse.group/u/hnrwagner)\ **Post date:** [November 10, 2025, 10:44am UTC](https://prepomax.discourse.group/t/prepomax-in-the-rr3-wind-turbine-tower-benchmark-sadowski-round-robin-2024-2025-results-observations/3049/33 "2025-11-10T10:44:17Z")
I will create a Tutorial regarding this example Tower for my YouTube Channel this month. ---
**Author:** ![AsuraEquation](https://avatars.discourse-cdn.com/v4/letter/a/6de8d8/32.png) [@AsuraEquation](https://prepomax.discourse.group/u/AsuraEquation)\ **Post date:** [November 10, 2025, 12:28pm UTC](https://prepomax.discourse.group/t/prepomax-in-the-rr3-wind-turbine-tower-benchmark-sadowski-round-robin-2024-2025-results-observations/3049/34 "2025-11-10T12:28:14Z")
> [@FEAnalyst](#): > > By Enterfea ? Of course, I learned about it from one of your posts here on the forum (I don’t write much, but I visit often). In my work, I use an approach very similar to that of your tutorials (the 3D model is nice to look at, but I think it’s essential to start with an analytical method or a simplified 2D model), so let’s say I have a very high opinion of your work and your advice. I decided to try the Eurocode course and fell in love with it, so I moved on to the non-linearity course (which was even cooler). He is a really great teacher. You know, courses are often either too theoretical or too practical, but his (and yours too) are perfect. > [@FEAnalyst](#): > > In fact, CalculiX has one true shell user element, but it’s very limited. Hopefully, more such elements will be added in the future. I am aware of that. One of the “problems” with open-source software is that it is very dependent on the opinions of those who write the code, who, having very limited time, cannot do everything. I imagine that Guido believes that there are other priorities, and that’s fine. The solver is incredible anyway and it’s also mathematically very robust (I recently discovered that in many ways it is better than Code Aster, which surprised me), and with a Pre and Post processor like PrePoMax, I am receiving on my desk more and more jobs done with Calculix. It’s just strange that it doesn’t have real support for 2D elements. > [@hnrwagner](#): > > I will create a Tutorial regarding this example Tower for my YouTube Channel this month. Can you share your Youtube channel? isn’t that the one with the orangutans? 🤣 If so, the Oceangate video is very, very interesting. I saw it some time ago and, if I’m not mistaken, PrePoMax appears at one point, although I think FEM was created with different software (or am I wrong?). > [@ANYS](#): > > My GMNIA it’s LPF=0.92 I am waiting for information on imperfection values (I am recreating the test myself). ---
**Author:** ![ANYS](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/anys/32/7737_2.png) [@ANYS](https://prepomax.discourse.group/u/ANYS)\ **Post date:** [November 10, 2025, 3:10pm UTC](https://prepomax.discourse.group/t/prepomax-in-the-rr3-wind-turbine-tower-benchmark-sadowski-round-robin-2024-2025-results-observations/3049/35 "2025-11-10T15:10:24Z")
> [@AsuraEquation](#): > > I am waiting for information on imperfection values (I am recreating the test myself). Don’t wait, finish the analysis using everything you’ve learned, and then we can see if we’re on the same page. It’ll be more interesting. ---
**Author:** ![hnrwagner](https://avatars.discourse-cdn.com/v4/letter/h/e8c25b/32.png) [@hnrwagner](https://prepomax.discourse.group/u/hnrwagner)\ **Post date:** [November 10, 2025, 9:47pm UTC](https://prepomax.discourse.group/t/prepomax-in-the-rr3-wind-turbine-tower-benchmark-sadowski-round-robin-2024-2025-results-observations/3049/36 "2025-11-10T21:47:23Z")
my YouTube Channel is here: > **[Heinz Wagner](https://www.youtube.com/@hnrwagner/videos)** > > Dr. Heinz Wagner – Shell Buckling, Simulation & Paradigm Shifts in Structural Mechanics > > Welcome to MDC Tech, the official channel of Dr. Ronald Wagner (TU Braunschweig), researcher and creator of the Mechanistic Design Curve (MDC) and the Hook... ---
**Author:** ![synt](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/synt/32/4658_2.png) [@synt](https://prepomax.discourse.group/u/synt)\ **Post date:** [November 12, 2025, 9:39am UTC](https://prepomax.discourse.group/t/prepomax-in-the-rr3-wind-turbine-tower-benchmark-sadowski-round-robin-2024-2025-results-observations/3049/37 "2025-11-12T09:39:45Z")
the problem of rigid body and shell element also been reported in CalculiX forum, out of plane rotational degrees not restrained as Abaqus does. Defining manually in user local coordinate system may solve the problems, an elegant way maybe instead of additional rigid part by material properties. \*edited probably, i have to expect too much. Trying to keep edge faces to stay plan cannot be succeed, solver divergences early. Latest CalculiX solver v2.23 clearly shown the limitation, it’s aborting this boundary condition setup. ![2025-11-12 21_20_14-](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/1/1e8cf8e2c51cf4ecb82e0790435700295c2a073b.png) ![2025-11-12 21_21_00-Output](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/6/691119bb38d46edb02ea7e8d2e0f5a252440caee.png) ---
**Author:** ![hnrwagner](https://avatars.discourse-cdn.com/v4/letter/h/e8c25b/32.png) [@hnrwagner](https://prepomax.discourse.group/u/hnrwagner)\ **Post date:** [November 14, 2025, 10:37am UTC](https://prepomax.discourse.group/t/prepomax-in-the-rr3-wind-turbine-tower-benchmark-sadowski-round-robin-2024-2025-results-observations/3049/38 "2025-11-14T10:37:00Z")
how did you apply the imperfection field to your model? it seems not to work for me, in Buckle Step I export the deformed (File → Export → Deformed Mesh inp) and in FE Model → Model → Tools → Update Nodal Coordinate From File but nothing happens, seems to have something to do with being a hybrid mesh because with only shells or solids it works fine, how do you do it? ---
**Author:** ![hnrwagner](https://avatars.discourse-cdn.com/v4/letter/h/e8c25b/32.png) [@hnrwagner](https://prepomax.discourse.group/u/hnrwagner)\ **Post date:** [November 14, 2025, 10:50am UTC](https://prepomax.discourse.group/t/prepomax-in-the-rr3-wind-turbine-tower-benchmark-sadowski-round-robin-2024-2025-results-observations/3049/39 "2025-11-14T10:50:07Z")
I also tried the “Thicken Shell Mesh” Feature now but I can only select the whole shell model and not individual section? how does this work? I just want to apply thicken shell mesh to the upper flange of the tower ---
**Author:** ![FEAnalyst](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/feanalyst/32/688_2.png) [@FEAnalyst](https://prepomax.discourse.group/u/FEAnalyst)\ **Post date:** [November 14, 2025, 10:50am UTC](https://prepomax.discourse.group/t/prepomax-in-the-rr3-wind-turbine-tower-benchmark-sadowski-round-robin-2024-2025-results-observations/3049/40 "2025-11-14T10:50:11Z")
> \*ERROR in gen3dmpc: nodes belonging to > shell elements must not be > subject to a RIGID MPC. Great, we have a major regression with respect to previous CalculiX versions - now in ccx 2.23 it’s not possible to use rigid body constraint with shells even if analysis doesn’t have Nlgeom. I guess I’ll have to talk with Guido about it. [Previous page](https://prepomax.discourse.group/t/prepomax-in-the-rr3-wind-turbine-tower-benchmark-sadowski-round-robin-2024-2025-results-observations/3049.md?page=1) [Next page](https://prepomax.discourse.group/t/prepomax-in-the-rr3-wind-turbine-tower-benchmark-sadowski-round-robin-2024-2025-results-observations/3049.md?page=3)