# HYPERFOAM Model Issue **URL:** \ **Category:** Analysis issues\ **Created:** [September 23, 2026, 11:12am UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115 "2026-09-23T11:12:54Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\ **Post date:** [September 25, 2026, 1:06pm UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/51 "2026-09-25T13:06:30Z")
> [@Durbul](#): > > Discourse has some automatic spam detection that is sometimes triggered if the same user posts many images. Can it be disabled or reduced ? Posting many images is the standard here. Unless it’s only for new users and stops working after some time. ---
**Author:** ![Viertelstein](https://avatars.discourse-cdn.com/v4/letter/v/e47c2d/32.png) [@Viertelstein](https://calculix.discourse.group/u/Viertelstein)\ **Post date:** [September 25, 2026, 1:11pm UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/52 "2026-09-25T13:11:26Z")
@Calc_em Getting that stupid error message again? I was trying to share the Google Drive link: “An error occurred: Sorry you cannot post a link to that host. usp=sharing” ---
**Author:** ![Durbul](https://avatars.discourse-cdn.com/v4/letter/d/8dc957/32.png) [@Durbul](https://calculix.discourse.group/u/Durbul)\ **Post date:** [September 25, 2026, 2:22pm UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/53 "2026-09-25T14:22:52Z")
It’s only for new users and a default setting. ---
**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\ **Post date:** [September 25, 2026, 2:24pm UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/54 "2026-09-25T14:24:12Z")
Ok, I guess we can live with that then. ---
**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\ **Post date:** [September 26, 2026, 2:13pm UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/56 "2026-09-26T14:13:16Z")
> [@Viertelstein](#): > > it’s **NOT** working again! What do you mean ? It doesn’t converge ? ---
**Author:** ![Viertelstein](https://avatars.discourse-cdn.com/v4/letter/v/e47c2d/32.png) [@Viertelstein](https://calculix.discourse.group/u/Viertelstein)\ **Post date:** [September 26, 2026, 2:18pm UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/57 "2026-09-26T14:18:14Z")
It fails. I open the same PMX from yesterday, no changes, but result is: average force= nan time avg. forc= 0.010000 largest residual force= 0.000000 in node 1429 and dof 3 largest increment of disp= 4.646660e+03 largest correction to disp= 8.506872e+02 in node 201 and dof 2 Job failed - no results exist. Process elapsed time: 46.891 s ---
**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\ **Post date:** [September 26, 2026, 2:49pm UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/58 "2026-09-26T14:49:26Z")
Maybe you should try resubmitting the analysis and checking if it’s the correct version of the model. And look for the .frd file from yesterday in your work directory - it should still be there. ---
**Author:** ![Viertelstein](https://avatars.discourse-cdn.com/v4/letter/v/e47c2d/32.png) [@Viertelstein](https://calculix.discourse.group/u/Viertelstein)\ **Post date:** [September 27, 2026, 5:33am UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/61 "2026-09-27T05:33:45Z")
Oh sorry … \*HYPERFOAM, N=2 0.02, 3.0, 0.02, 3.0, 0.05, 0.05 ---
**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\ **Post date:** [September 27, 2026, 11:26am UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/64 "2026-09-27T11:26:48Z")
Good news - CalculiX devs are already working on a fix for this bug: [Hyperfoam material model showing incorrect deformation with no stresses · Issue #188 · Dhondtguido/CalculiX · GitHub](https://github.com/Dhondtguido/CalculiX/issues/188#issuecomment-5853332008) It most likely won’t help with convergence issues, though. So it’s necessary to have reasonable constants for this model. ---
**Author:** ![fgr](https://avatars.discourse-cdn.com/v4/letter/f/f4b2a3/32.png) [@fgr](https://calculix.discourse.group/u/fgr)\ **Post date:** [September 27, 2026, 12:08pm UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/65 "2026-09-27T12:08:54Z")
@Viertelstein , I don’t know from where you have your material parameters for your foam, but as described by @Disla [HYPERFOAM Model Issue - #29 by Disla](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/29) when you insert twice the material parameters, you will also double the energy in the structure, so to correcting this issue, you will need to half the material energy parameter why these values will be more correct ```auto *HYPERFOAM, N=2 0.01, 3.0, 0.01, 3.0, 0.05, 0.05 ``` compared to these values which will double the energy content ```auto *HYPERFOAM, N=2 0.02, 3.0, 0.02, 3.0, 0.05, 0.05 ``` ---
**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\ **Post date:** [September 27, 2026, 1:08pm UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/67 "2026-09-27T13:08:47Z")
Yeah, the equation for the strain energy potential in this model is: ![image](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/e/eba35944a610a9144f25f188e4e3e96883ccbdea.png) where N is the parameter that you can change on the keyword data line. So, when you increase N, you also increase the number of terms added in this sum and thus add more strain energy. ---
**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\ **Post date:** [September 27, 2026, 1:09pm UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/68 "2026-09-27T13:09:49Z")
> [@Viertelstein](#): > > Btw, adding “concentrated force” and “Surface Behaviour TIED” all my models run much better. Just make sure that you apply concentrated force only to reference points, not to entire faces. Tied contact is fine, but tie constraints usually works better. > [@Viertelstein](#): > > Not sure why the holes are inside of the stamp, but I will find out. 😅 This is 1.9x scaled deformation, check true scale. But maybe your contact stiffness is too low. ---
**Author:** ![MisiaKu](https://avatars.discourse-cdn.com/v4/letter/m/e5b9ba/32.png) [@MisiaKu](https://calculix.discourse.group/u/MisiaKu)\ **Post date:** [September 27, 2026, 4:55pm UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/69 "2026-09-27T16:55:30Z")
Sorry, I confused Hyperelasticity with Hyperfoam. The phone has a small screen. ---
**Author:** ![Viertelstein](https://avatars.discourse-cdn.com/v4/letter/v/e47c2d/32.png) [@Viertelstein](https://calculix.discourse.group/u/Viertelstein)\ **Post date:** [September 28, 2026, 12:27am UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/70 "2026-09-28T00:27:42Z")
I tried different settings in SURFACE INTERACTIONS. TIED with different values (which still works best in generell), HARD, LINEAR and EXPONENTIAL, all fail sooner or later. TIED still shows overlapping geometries and a “finished job” without reaching TOT TIME 1.0 (is this because of CONCENTRATED FORCE (=no specified penetration value)? ![image](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/3/3f8940094a5dc872ae3a33d838b49126c260a4e9.png) ![image](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/6/68aac1503cb0a7640cacaee1ed0b3958d40c4d87.jpeg) ---
**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\ **Post date:** [September 28, 2026, 5:14am UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/71 "2026-09-28T05:14:09Z")
Displacement control would be better, at least for convergence. But it shouldn’t penetrate so much with force control either. Make sure that contact is properly defined - correct surfaces are selected, master has a coarser mesh and belongs to the stiffer or rigid part. If it still doesn’t work, please share the file here. Maybe it’s still an issue with this material model. ---
**Author:** ![Viertelstein](https://avatars.discourse-cdn.com/v4/letter/v/e47c2d/32.png) [@Viertelstein](https://calculix.discourse.group/u/Viertelstein)\ **Post date:** [September 28, 2026, 6:03am UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/72 "2026-09-28T06:03:54Z")
One big mistake from my side! I have to mark ALL surfaces for propper contact! Together with 10 mm mesh for the stamp and 3 mm for the latexblock it looks pretty good! ![gggggq1112222](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/6/6e8d4979462104811dac6392aa4656615df5eef7.png) ![gggggq11122223333](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/9/92c6bf47cde4da5bafc61e5fa39843db26c0c696.png) ![gggggq111](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/e/e6fbd392449c838336aa9dfcb1b2d1c5e77a5ad4.jpeg) ---
**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\ **Post date:** [September 28, 2026, 6:57am UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/73 "2026-09-28T06:57:51Z")
Yeah, that would definitely explain it. Contact regions shouldn’t spread too far, but they must cover all areas that may touch during the deformation. ---
**Author:** ![Viertelstein](https://avatars.discourse-cdn.com/v4/letter/v/e47c2d/32.png) [@Viertelstein](https://calculix.discourse.group/u/Viertelstein)\ **Post date:** [September 28, 2026, 11:55pm UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/74 "2026-09-28T23:55:48Z")
Why only 20% of the job can be done? (that’s what AI is telling me about TOT TIME 0.2) ![20 prozent 1](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/3/36039186dcc1eb929d329a1f2d9b90ad0ec8db7a.jpeg) ![20 proezent](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/7/7b5f6adb467c231a4abe669d38ea926f734e3b00.png) ---
**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\ **Post date:** [September 29, 2026, 5:37am UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/75 "2026-09-29T05:37:50Z")
Assuming that your step time is the default 1 s (better check that), it might be an issue with reading the CalculiX results in PrePoMax. Sometimes this may happen. You can try rerunning, check the CalculiX log or even run the analysis from the .inp file outside of PrePoMax (using standalone CalculiX). ---
**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\ **Post date:** [September 29, 2026, 8:30am UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/77 "2026-09-29T08:30:44Z")
> [@Viertelstein](#): > > With the material setting _HYPERFOAM, N=2 0.002, 3.0, 0.002, 3.0, 0.05, 0.05_, PreProMax reach exactly 6.9 mm! But how did you load it in the analysis ? So far you’ve been using prescribed displacement. [Previous page](https://calculix.discourse.group/t/hyperfoam-model-issue/4115.md?page=2) [Next page](https://calculix.discourse.group/t/hyperfoam-model-issue/4115.md?page=4)