# HYPERFOAM Model Issue **URL:** https://calculix.discourse.group/t/hyperfoam-model-issue/4115 **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:** 1
### Author: ![Viertelstein](https://avatars.discourse-cdn.com/v4/letter/v/e47c2d/32.png) [@Viertelstein](https://calculix.discourse.group/u/Viertelstein) #### Post date: [September 23, 2026, 11:12am UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/1 "2026-09-23T11:12:54Z")
Hi All, We discussed my set-up with latex foam in [https://prepomax.discourse.group/](https://prepomax.discourse.group/). Same setting works well in ABAQUS, but not with CalculiX, thus, I have been asked to open an additional discussion here, the more so, I would like to share some data to support this community to find a solution. Best, Viertelstein PS: I assume uploads of ASCII files will be possible once the topic is published? Here are some basics about the samples tested from Kunststoffzentrum Leipzig (Original German, English translation): Druckspannungswert (Stauchhärte) CV40 nach DIN EN ISO 3386-1:2015-10 Latexschaum Probekörper 50 mm × 50 mm × 25 mm Das Probenmaterial wurde vor Beginn der Prüfungen mehr als 24 h bei Normklima 23/50 Klasse 2 nach DIN EN ISO 291:2008-08 gelagert. Druckspannungswert (Stauchhärte) CV40 nach DIN EN ISO 3386-1:2015-10 Prüfeinrichtung: Universalprüfmaschine Zwicki Z2,5 TH, Zwick GmbH & Co. KG| Probekörper: 50 mm × 50 mm × 25 mm , Anzahl: 7 Prüfgeschwindigkeit: Setzzyklus: 100 mm/min, Messzyklus: 100 mm/min, Prüftemperatur: 23°C Compressive stress value (indentation hardness) CV40 according to DIN EN ISO 3386-1:2015-10; latex foam test specimens 50 mm × 50 mm × 25 mm. Prior to testing, the sample material was conditioned for more than 24 hours in a standard atmosphere (23/50, Class 2) according to DIN EN ISO 291:2008-08. Compressive stress value (indentation hardness) CV40 according to DIN EN ISO 3386-1:2015-10; testing equipment: Zwicki Z2.5 TH universal testing machine (Zwick GmbH & Co. KG); test specimens: 50 mm × 50 mm × 25 mm, quantity: 7; testing speed: pre-loading cycle: 100 mm/min, measurement cycle: 100 mm/min; test temperature: 23°C. ---
### Author: ![Viertelstein](https://avatars.discourse-cdn.com/v4/letter/v/e47c2d/32.png) [@Viertelstein](https://calculix.discourse.group/u/Viertelstein) #### Post date: [September 23, 2026, 11:16am UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/2 "2026-09-23T11:16:59Z")
> **[Leipzig - Google Drive](https://drive.google.com/drive/folders/1USR2jkM143RipzFb1k3eGaGW15dfJyFt?usp=sharing)** ---
### 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 23, 2026, 12:10pm UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/3 "2026-09-23T12:10:58Z")
Most importantly, I’d like to add that I’ve noticed a potential bug with this material model and I would appreciate if someone could confirm it: ![hyperfoam ccx](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/9/9ff1a501f6867d029c74c62ded695353593cf705.gif) Here’s the input deck: [Dropbox](https://www.dropbox.com/scl/fi/v6ly8lhmmbkvsiqid5cu4/hyperfoam_issue_ccx.inp?rlkey=jaldfxgn8oddfrqdahibaaqt4&st=r74oljow&dl=0) ---
### Author: ![Viertelstein](https://avatars.discourse-cdn.com/v4/letter/v/e47c2d/32.png) [@Viertelstein](https://calculix.discourse.group/u/Viertelstein) #### Post date: [September 23, 2026, 12:24pm UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/4 "2026-09-23T12:24:33Z")
I can fully confirm, since 2 days this happen to me. However all other conditions are, the edges stay fixed. ![mistake](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/0/09a60736b2aa2db2d6eceb33ea1ab388f447ae1c.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 23, 2026, 12:39pm UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/5 "2026-09-23T12:39:32Z")
It seems to be a fault of the hyperfoam material model. It doesn’t seem to happen with hyperelasticity. And it works normally with the same input deck in Abaqus: ![image](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/8/8963c352fdac717aa7c7044a663b5c137fffccc5.png) ---
### Author: ![Viertelstein](https://avatars.discourse-cdn.com/v4/letter/v/e47c2d/32.png) [@Viertelstein](https://calculix.discourse.group/u/Viertelstein) #### Post date: [September 23, 2026, 12:44pm UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/6 "2026-09-23T12:44:57Z")
I heard/saw that before. With ABAQUS it looks pretty well, but NOT with CALCULIX. Someone mentioned it is an internal error (bug?). ---
### 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 23, 2026, 12:48pm UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/7 "2026-09-23T12:48:28Z")
> [@Viertelstein](#): > > I heard/saw that before. Yeah, it’s for the CalculiX community to show that the hyperfoam model seems to have some issues. Looks like a bug, but should be confirmed by someone. And we may need a minimum reproducible example like a small cube. ---
### Author: ![Viertelstein](https://avatars.discourse-cdn.com/v4/letter/v/e47c2d/32.png) [@Viertelstein](https://calculix.discourse.group/u/Viertelstein) #### Post date: [September 23, 2026, 12:51pm UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/8 "2026-09-23T12:51:48Z")
> **[hyperfoam grad geaendert.pmx](https://drive.google.com/file/d/18k_OfLaLJbzs3Y8qY8SS1dB7F7fNDjxI/view?usp=sharing)** > > Google Drive file. ---
### 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 23, 2026, 1:11pm UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/9 "2026-09-23T13:11:37Z")
@Viertelstein For the next time, it would be good if you could also share the CalculiX .inp file exported from the PrePoMax file (since many users here work in other preprocessors). But I’ve already shared the model showing the bug above (via Dropbox) so no worries for now. Btw. to clarify, I’m FEAnalyst from the PrePoMax forum. ---
### 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 23, 2026, 1:41pm UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/10 "2026-09-23T13:41:27Z")
Issue shown with just two elements: ![image](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/1/136e5ef32351e023f57951fa6bd615523c53701e.png) Input file: ```auto *Node 1, 0.00000000E+000, 0.00000000E+000, 0.00000000E+000 2, 0.00000000E+000, 0.00000000E+000, 1.00000000E+001 3, 0.00000000E+000, 1.00000000E+001, 0.00000000E+000 4, 0.00000000E+000, 1.00000000E+001, 1.00000000E+001 5, 1.00000000E+001, 0.00000000E+000, 0.00000000E+000 6, 1.00000000E+001, 0.00000000E+000, 1.00000000E+001 7, 1.00000000E+001, 1.00000000E+001, 0.00000000E+000 8, 1.00000000E+001, 1.00000000E+001, 1.00000000E+001 9, 0.00000000E+000, 0.00000000E+000, 1.00000000E+001 10, 0.00000000E+000, 0.00000000E+000, 2.00000000E+001 11, 0.00000000E+000, 1.00000000E+001, 1.00000000E+001 12, 0.00000000E+000, 1.00000000E+001, 2.00000000E+001 13, 1.00000000E+001, 0.00000000E+000, 1.00000000E+001 14, 1.00000000E+001, 0.00000000E+000, 2.00000000E+001 15, 1.00000000E+001, 1.00000000E+001, 1.00000000E+001 16, 1.00000000E+001, 1.00000000E+001, 2.00000000E+001 17, 5.00000000E+000, 5.00000000E+000, 2.00000000E+001 18, 5.00000000E+000, 5.00000000E+000, 2.00000000E+001 *Element, Type=C3D8, Elset=Solid_part-1 1, 4, 2, 1, 3, 8, 6, 5, 7 *Element, Type=C3D8, Elset=Solid_part-2 2, 12, 10, 9, 11, 16, 14, 13, 15 *Nset, Nset=Top_part 9, 10, 11, 12, 13, 14, 15, 16 *Nset, Nset=Internal-1_Contact_top 9, 11, 13, 15 *Nset, Nset=Internal-1_Contact_bot 2, 4, 6, 8 *Nset, Nset=Fixed_bot 1, 3, 5, 7 *Nset, Nset=Reference_Point-1_Ref_161 17 *Nset, Nset=Reference_Point-1_Rot_171 18 *Elset, Elset=Internal-1_Contact_top_S5 2 *Elset, Elset=Internal-1_Contact_bot_S3 1 *Elset, Elset=Top_part_elset 2 *Elset, Elset=Bot_part_elset 1 *Surface, Name=Contact_top, Type=Element Internal-1_Contact_top_S5, S5 *Surface, Name=Contact_bot, Type=Element Internal-1_Contact_bot_S3, S3 *Material, Name=Steel *Elastic 210000, 0.3 *Material, Name=Foam *HYPERFOAM, N=1 0.02, 3.0, 0.05 *Solid section, Elset=Top_part_elset, Material=Steel *Solid section, Elset=Bot_part_elset, Material=Foam *Rigid body, Nset=Top_part, Ref node=17, Rot node=18 *Surface interaction, Name=Surface_Interaction-1 *Surface behavior, Pressure-overclosure=Hard *Friction 0.1 *Contact pair, Interaction=Surface_Interaction-1, Type=Surface to surface Contact_bot, Contact_top *Step, Nlgeom *Static, Solver=Pardiso *Boundary, op=New *Boundary Fixed_bot, 1, 6, 0 *Boundary 17, 1, 1, 0 17, 2, 2, 0 17, 3, 3, -4 18, 1, 1, 0 18, 2, 2, 0 18, 3, 3, 0 *Node file RF, U *El file S, E, NOE *End step ``` ---
### 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 23, 2026, 1:45pm UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/11 "2026-09-23T13:45:17Z")
But it can be even shown with one element too (so nothing to do with contact or rigid body, just the material model): ```auto *Node 1, 0.00000000E+000, 0.00000000E+000, 0.00000000E+000 2, 0.00000000E+000, 0.00000000E+000, 1.00000000E+001 3, 0.00000000E+000, 1.00000000E+001, 0.00000000E+000 4, 0.00000000E+000, 1.00000000E+001, 1.00000000E+001 5, 1.00000000E+001, 0.00000000E+000, 0.00000000E+000 6, 1.00000000E+001, 0.00000000E+000, 1.00000000E+001 7, 1.00000000E+001, 1.00000000E+001, 0.00000000E+000 8, 1.00000000E+001, 1.00000000E+001, 1.00000000E+001 *Element, Type=C3D8, Elset=Solid_part-1 1, 4, 2, 1, 3, 8, 6, 5, 7 *Nset, Nset=Fixed_bot 1, 3, 5, 7 *Nset, Nset=Loaded_top 2, 4, 6, 8 *Elset, Elset=Foam_cube_elset 1 *Material, Name=Foam *HYPERFOAM, N=1 0.02, 3.0, 0.05 *Solid section, Elset=Foam_cube_elset, Material=Foam *Step, Nlgeom *Static, Solver=Pardiso *Boundary Fixed_bot, 1, 6, 0 *Boundary Loaded_top, 1, 1, 0 Loaded_top, 2, 2, 0 Loaded_top, 3, 3, -4 Loaded_top, 4, 4, 0 Loaded_top, 5, 5, 0 Loaded_top, 6, 6, 0 *Node file RF, U *El file S, E, NOE *End step ``` ---
### Author: ![fgr](https://avatars.discourse-cdn.com/v4/letter/f/f4b2a3/32.png) [@fgr](https://calculix.discourse.group/u/fgr) #### Post date: [September 23, 2026, 2:39pm UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/12 "2026-09-23T14:39:03Z")
@Viertelstein It seemed to be a bug in ccx. A quick workaround for you could be just to add the material parameters twice like this: ```auto *Material, Name=Latexschaum *HYPERFOAM, N=2 0.02, 3.0, 0.02, 3.0, 0.05, 0.05 ``` It should give you this result. ![image](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/6/6c4c7054bb135204b3458ffc654aa2cfc68af266.png) ---
### Author: ![JuanP74](https://avatars.discourse-cdn.com/v4/letter/j/b5a626/32.png) [@JuanP74](https://calculix.discourse.group/u/JuanP74) #### Post date: [September 23, 2026, 2:42pm UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/13 "2026-09-23T14:42:40Z")
I run the calculix test example `beamhf.inp` using your material model and it runs with the example material model _HY_ but not with _Latexschaum_ material model so could be a mix of both problems, in ccx and in the material model. > > **beamhf.inp** > > > > \*\* > > \*\* Structure: cantilever beam. > > \*\* Test objective: hyperfoam material (N=2) under tension. > > \*\* > > \*HEADING > > Model: beam Date: 10-Mar-1998 > > \*NODE > > 1, 0.000000, 0.000000, 0.000000 > > 2, 1.000000, 0.000000, 0.000000 > > 3, 1.000000, 1.000000, 0.000000 > > 4, 0.000000, 1.000000, 0.000000 > > 5, 0.000000, 0.000000, 8.000000 > > 6, 1.000000, 0.000000, 8.000000 > > 7, 1.000000, 1.000000, 8.000000 > > 8, 0.000000, 1.000000, 8.000000 > > 9, 0.250000, 0.000000, 0.000000 > > 10, 0.500000, 0.000000, 0.000000 > > 11, 0.750000, 0.000000, 0.000000 > > 12, 1.000000, 0.250000, 0.000000 > > 13, 1.000000, 0.500000, 0.000000 > > 14, 1.000000, 0.750000, 0.000000 > > 15, 0.750000, 1.000000, 0.000000 > > 16, 0.500000, 1.000000, 0.000000 > > 17, 0.250000, 1.000000, 0.000000 > > 18, 0.000000, 0.750000, 0.000000 > > 19, 0.000000, 0.500000, 0.000000 > > 20, 0.000000, 0.250000, 0.000000 > > 21, 0.250000, 0.000000, 8.000000 > > 22, 0.500000, 0.000000, 8.000000 > > 23, 0.750000, 0.000000, 8.000000 > > 24, 1.000000, 0.250000, 8.000000 > > 25, 1.000000, 0.500000, 8.000000 > > 26, 1.000000, 0.750000, 8.000000 > > 27, 0.750000, 1.000000, 8.000000 > > 28, 0.500000, 1.000000, 8.000000 > > 29, 0.250000, 1.000000, 8.000000 > > 30, 0.000000, 0.750000, 8.000000 > > 31, 0.000000, 0.500000, 8.000000 > > 32, 0.000000, 0.250000, 8.000000 > > 33, 1.000000, 0.000000, 0.500000 > > 34, 1.000000, 0.000000, 1.000000 > > 35, 1.000000, 0.000000, 1.500000 > > 36, 1.000000, 0.000000, 2.000000 > > 37, 1.000000, 0.000000, 2.500000 > > 38, 1.000000, 0.000000, 3.000000 > > 39, 1.000000, 0.000000, 3.500000 > > 40, 1.000000, 0.000000, 4.000000 > > 41, 1.000000, 0.000000, 4.500000 > > 42, 1.000000, 0.000000, 5.000000 > > 43, 1.000000, 0.000000, 5.500000 > > 44, 1.000000, 0.000000, 6.000000 > > 45, 1.000000, 0.000000, 6.500000 > > 46, 1.000000, 0.000000, 7.000000 > > 47, 1.000000, 0.000000, 7.500000 > > 48, 0.000000, 0.000000, 7.500000 > > 49, 0.000000, 0.000000, 7.000000 > > 50, 0.000000, 0.000000, 6.500000 > > 51, 0.000000, 0.000000, 6.000000 > > 52, 0.000000, 0.000000, 5.500000 > > 53, 0.000000, 0.000000, 5.000000 > > 54, 0.000000, 0.000000, 4.500000 > > 55, 0.000000, 0.000000, 4.000000 > > 56, 0.000000, 0.000000, 3.500000 > > 57, 0.000000, 0.000000, 3.000000 > > 58, 0.000000, 0.000000, 2.500000 > > 59, 0.000000, 0.000000, 2.000000 > > 60, 0.000000, 0.000000, 1.500000 > > 61, 0.000000, 0.000000, 1.000000 > > 62, 0.000000, 0.000000, 0.500000 > > 63, 1.000000, 1.000000, 0.500000 > > 64, 1.000000, 1.000000, 1.000000 > > 65, 1.000000, 1.000000, 1.500000 > > 66, 1.000000, 1.000000, 2.000000 > > 67, 1.000000, 1.000000, 2.500000 > > 68, 1.000000, 1.000000, 3.000000 > > 69, 1.000000, 1.000000, 3.500000 > > 70, 1.000000, 1.000000, 4.000000 > > 71, 1.000000, 1.000000, 4.500000 > > 72, 1.000000, 1.000000, 5.000000 > > 73, 1.000000, 1.000000, 5.500000 > > 74, 1.000000, 1.000000, 6.000000 > > 75, 1.000000, 1.000000, 6.500000 > > 76, 1.000000, 1.000000, 7.000000 > > 77, 1.000000, 1.000000, 7.500000 > > 78, 0.000000, 1.000000, 0.500000 > > 79, 0.000000, 1.000000, 1.000000 > > 80, 0.000000, 1.000000, 1.500000 > > 81, 0.000000, 1.000000, 2.000000 > > 82, 0.000000, 1.000000, 2.500000 > > 83, 0.000000, 1.000000, 3.000000 > > 84, 0.000000, 1.000000, 3.500000 > > 85, 0.000000, 1.000000, 4.000000 > > 86, 0.000000, 1.000000, 4.500000 > > 87, 0.000000, 1.000000, 5.000000 > > 88, 0.000000, 1.000000, 5.500000 > > 89, 0.000000, 1.000000, 6.000000 > > 90, 0.000000, 1.000000, 6.500000 > > 91, 0.000000, 1.000000, 7.000000 > > 92, 0.000000, 1.000000, 7.500000 > > 93, 0.500000, 0.250000, 0.000000 > > 94, 0.250000, 0.500000, 0.000000 > > 95, 0.500000, 0.500000, 0.000000 > > 96, 0.750000, 0.500000, 0.000000 > > 97, 0.500000, 0.750000, 0.000000 > > 98, 0.500000, 0.250000, 8.000000 > > 99, 0.250000, 0.500000, 8.000000 > > 100, 0.500000, 0.500000, 8.000000 > > 101, 0.750000, 0.500000, 8.000000 > > 102, 0.500000, 0.750000, 8.000000 > > 103, 0.500000, 0.000000, 0.500000 > > 104, 0.250000, 0.000000, 1.000000 > > 105, 0.500000, 0.000000, 1.000000 > > 106, 0.750000, 0.000000, 1.000000 > > 107, 0.500000, 0.000000, 1.500000 > > 108, 0.250000, 0.000000, 2.000000 > > 109, 0.500000, 0.000000, 2.000000 > > 110, 0.750000, 0.000000, 2.000000 > > 111, 0.500000, 0.000000, 2.500000 > > 112, 0.250000, 0.000000, 3.000000 > > 113, 0.500000, 0.000000, 3.000000 > > 114, 0.750000, 0.000000, 3.000000 > > 115, 0.500000, 0.000000, 3.500000 > > 116, 0.250000, 0.000000, 4.000000 > > 117, 0.500000, 0.000000, 4.000000 > > 118, 0.750000, 0.000000, 4.000000 > > 119, 0.500000, 0.000000, 4.500000 > > 120, 0.250000, 0.000000, 5.000000 > > 121, 0.500000, 0.000000, 5.000000 > > 122, 0.750000, 0.000000, 5.000000 > > 123, 0.500000, 0.000000, 5.500000 > > 124, 0.250000, 0.000000, 6.000000 > > 125, 0.500000, 0.000000, 6.000000 > > 126, 0.750000, 0.000000, 6.000000 > > 127, 0.500000, 0.000000, 6.500000 > > 128, 0.250000, 0.000000, 7.000000 > > 129, 0.500000, 0.000000, 7.000000 > > 130, 0.750000, 0.000000, 7.000000 > > 131, 0.500000, 0.000000, 7.500000 > > 132, 1.000000, 0.500000, 0.500000 > > 133, 1.000000, 0.250000, 1.000000 > > 134, 1.000000, 0.500000, 1.000000 > > 135, 1.000000, 0.750000, 1.000000 > > 136, 1.000000, 0.500000, 1.500000 > > 137, 1.000000, 0.250000, 2.000000 > > 138, 1.000000, 0.500000, 2.000000 > > 139, 1.000000, 0.750000, 2.000000 > > 140, 1.000000, 0.500000, 2.500000 > > 141, 1.000000, 0.250000, 3.000000 > > 142, 1.000000, 0.500000, 3.000000 > > 143, 1.000000, 0.750000, 3.000000 > > 144, 1.000000, 0.500000, 3.500000 > > 145, 1.000000, 0.250000, 4.000000 > > 146, 1.000000, 0.500000, 4.000000 > > 147, 1.000000, 0.750000, 4.000000 > > 148, 1.000000, 0.500000, 4.500000 > > 149, 1.000000, 0.250000, 5.000000 > > 150, 1.000000, 0.500000, 5.000000 > > 151, 1.000000, 0.750000, 5.000000 > > 152, 1.000000, 0.500000, 5.500000 > > 153, 1.000000, 0.250000, 6.000000 > > 154, 1.000000, 0.500000, 6.000000 > > 155, 1.000000, 0.750000, 6.000000 > > 156, 1.000000, 0.500000, 6.500000 > > 157, 1.000000, 0.250000, 7.000000 > > 158, 1.000000, 0.500000, 7.000000 > > 159, 1.000000, 0.750000, 7.000000 > > 160, 1.000000, 0.500000, 7.500000 > > 161, 0.500000, 1.000000, 0.500000 > > 162, 0.750000, 1.000000, 1.000000 > > 163, 0.500000, 1.000000, 1.000000 > > 164, 0.250000, 1.000000, 1.000000 > > 165, 0.500000, 1.000000, 1.500000 > > 166, 0.750000, 1.000000, 2.000000 > > 167, 0.500000, 1.000000, 2.000000 > > 168, 0.250000, 1.000000, 2.000000 > > 169, 0.500000, 1.000000, 2.500000 > > 170, 0.750000, 1.000000, 3.000000 > > 171, 0.500000, 1.000000, 3.000000 > > 172, 0.250000, 1.000000, 3.000000 > > 173, 0.500000, 1.000000, 3.500000 > > 174, 0.750000, 1.000000, 4.000000 > > 175, 0.500000, 1.000000, 4.000000 > > 176, 0.250000, 1.000000, 4.000000 > > 177, 0.500000, 1.000000, 4.500000 > > 178, 0.750000, 1.000000, 5.000000 > > 179, 0.500000, 1.000000, 5.000000 > > 180, 0.250000, 1.000000, 5.000000 > > 181, 0.500000, 1.000000, 5.500000 > > 182, 0.750000, 1.000000, 6.000000 > > 183, 0.500000, 1.000000, 6.000000 > > 184, 0.250000, 1.000000, 6.000000 > > 185, 0.500000, 1.000000, 6.500000 > > 186, 0.750000, 1.000000, 7.000000 > > 187, 0.500000, 1.000000, 7.000000 > > 188, 0.250000, 1.000000, 7.000000 > > 189, 0.500000, 1.000000, 7.500000 > > 190, 0.000000, 0.500000, 0.500000 > > 191, 0.000000, 0.750000, 1.000000 > > 192, 0.000000, 0.500000, 1.000000 > > 193, 0.000000, 0.250000, 1.000000 > > 194, 0.000000, 0.500000, 1.500000 > > 195, 0.000000, 0.750000, 2.000000 > > 196, 0.000000, 0.500000, 2.000000 > > 197, 0.000000, 0.250000, 2.000000 > > 198, 0.000000, 0.500000, 2.500000 > > 199, 0.000000, 0.750000, 3.000000 > > 200, 0.000000, 0.500000, 3.000000 > > 201, 0.000000, 0.250000, 3.000000 > > 202, 0.000000, 0.500000, 3.500000 > > 203, 0.000000, 0.750000, 4.000000 > > 204, 0.000000, 0.500000, 4.000000 > > 205, 0.000000, 0.250000, 4.000000 > > 206, 0.000000, 0.500000, 4.500000 > > 207, 0.000000, 0.750000, 5.000000 > > 208, 0.000000, 0.500000, 5.000000 > > 209, 0.000000, 0.250000, 5.000000 > > 210, 0.000000, 0.500000, 5.500000 > > 211, 0.000000, 0.750000, 6.000000 > > 212, 0.000000, 0.500000, 6.000000 > > 213, 0.000000, 0.250000, 6.000000 > > 214, 0.000000, 0.500000, 6.500000 > > 215, 0.000000, 0.750000, 7.000000 > > 216, 0.000000, 0.500000, 7.000000 > > 217, 0.000000, 0.250000, 7.000000 > > 218, 0.000000, 0.500000, 7.500000 > > 219, 0.500000, 0.500000, 0.500000 > > 220, 0.500000, 0.250000, 1.000000 > > 221, 0.250000, 0.500000, 1.000000 > > 222, 0.500000, 0.500000, 1.000000 > > 223, 0.750000, 0.500000, 1.000000 > > 224, 0.500000, 0.750000, 1.000000 > > 225, 0.500000, 0.500000, 1.500000 > > 226, 0.500000, 0.250000, 2.000000 > > 227, 0.250000, 0.500000, 2.000000 > > 228, 0.500000, 0.500000, 2.000000 > > 229, 0.750000, 0.500000, 2.000000 > > 230, 0.500000, 0.750000, 2.000000 > > 231, 0.500000, 0.500000, 2.500000 > > 232, 0.500000, 0.250000, 3.000000 > > 233, 0.250000, 0.500000, 3.000000 > > 234, 0.500000, 0.500000, 3.000000 > > 235, 0.750000, 0.500000, 3.000000 > > 236, 0.500000, 0.750000, 3.000000 > > 237, 0.500000, 0.500000, 3.500000 > > 238, 0.500000, 0.250000, 4.000000 > > 239, 0.250000, 0.500000, 4.000000 > > 240, 0.500000, 0.500000, 4.000000 > > 241, 0.750000, 0.500000, 4.000000 > > 242, 0.500000, 0.750000, 4.000000 > > 243, 0.500000, 0.500000, 4.500000 > > 244, 0.500000, 0.250000, 5.000000 > > 245, 0.250000, 0.500000, 5.000000 > > 246, 0.500000, 0.500000, 5.000000 > > 247, 0.750000, 0.500000, 5.000000 > > 248, 0.500000, 0.750000, 5.000000 > > 249, 0.500000, 0.500000, 5.500000 > > 250, 0.500000, 0.250000, 6.000000 > > 251, 0.250000, 0.500000, 6.000000 > > 252, 0.500000, 0.500000, 6.000000 > > 253, 0.750000, 0.500000, 6.000000 > > 254, 0.500000, 0.750000, 6.000000 > > 255, 0.500000, 0.500000, 6.500000 > > 256, 0.500000, 0.250000, 7.000000 > > 257, 0.250000, 0.500000, 7.000000 > > 258, 0.500000, 0.500000, 7.000000 > > 259, 0.750000, 0.500000, 7.000000 > > 260, 0.500000, 0.750000, 7.000000 > > 261, 0.500000, 0.500000, 7.500000 > > \*ELEMENT, TYPE=C3D20R , ELSET=B1 > > 1, 1, 10, 95, 19, 61, 105, 222, 192, 9, 93, > > 94, 20, 104, 220, 221, 193, 62, 103, 219, 190 > > 2, 10, 2, 13, 95, 105, 34, 134, 222, 11, 12, > > 96, 93, 106, 133, 223, 220, 103, 33, 132, 219 > > 3, 19, 95, 16, 4, 192, 222, 163, 79, 94, 97, > > 17, 18, 221, 224, 164, 191, 190, 219, 161, 78 > > 4, 95, 13, 3, 16, 222, 134, 64, 163, 96, 14, > > 15, 97, 223, 135, 162, 224, 219, 132, 63, 161 > > 5, 61, 105, 222, 192, 59, 109, 228, 196, 104, 220, > > 221, 193, 108, 226, 227, 197, 60, 107, 225, 194 > > 6, 105, 34, 134, 222, 109, 36, 138, 228, 106, 133, > > 223, 220, 110, 137, 229, 226, 107, 35, 136, 225 > > 7, 192, 222, 163, 79, 196, 228, 167, 81, 221, 224, > > 164, 191, 227, 230, 168, 195, 194, 225, 165, 80 > > 8, 222, 134, 64, 163, 228, 138, 66, 167, 223, 135, > > 162, 224, 229, 139, 166, 230, 225, 136, 65, 165 > > 9, 59, 109, 228, 196, 57, 113, 234, 200, 108, 226, > > 227, 197, 112, 232, 233, 201, 58, 111, 231, 198 > > 10, 109, 36, 138, 228, 113, 38, 142, 234, 110, 137, > > 229, 226, 114, 141, 235, 232, 111, 37, 140, 231 > > 11, 196, 228, 167, 81, 200, 234, 171, 83, 227, 230, > > 168, 195, 233, 236, 172, 199, 198, 231, 169, 82 > > 12, 228, 138, 66, 167, 234, 142, 68, 171, 229, 139, > > 166, 230, 235, 143, 170, 236, 231, 140, 67, 169 > > 13, 57, 113, 234, 200, 55, 117, 240, 204, 112, 232, > > 233, 201, 116, 238, 239, 205, 56, 115, 237, 202 > > 14, 113, 38, 142, 234, 117, 40, 146, 240, 114, 141, > > 235, 232, 118, 145, 241, 238, 115, 39, 144, 237 > > 15, 200, 234, 171, 83, 204, 240, 175, 85, 233, 236, > > 172, 199, 239, 242, 176, 203, 202, 237, 173, 84 > > 16, 234, 142, 68, 171, 240, 146, 70, 175, 235, 143, > > 170, 236, 241, 147, 174, 242, 237, 144, 69, 173 > > 17, 55, 117, 240, 204, 53, 121, 246, 208, 116, 238, > > 239, 205, 120, 244, 245, 209, 54, 119, 243, 206 > > 18, 117, 40, 146, 240, 121, 42, 150, 246, 118, 145, > > 241, 238, 122, 149, 247, 244, 119, 41, 148, 243 > > 19, 204, 240, 175, 85, 208, 246, 179, 87, 239, 242, > > 176, 203, 245, 248, 180, 207, 206, 243, 177, 86 > > 20, 240, 146, 70, 175, 246, 150, 72, 179, 241, 147, > > 174, 242, 247, 151, 178, 248, 243, 148, 71, 177 > > 21, 53, 121, 246, 208, 51, 125, 252, 212, 120, 244, > > 245, 209, 124, 250, 251, 213, 52, 123, 249, 210 > > 22, 121, 42, 150, 246, 125, 44, 154, 252, 122, 149, > > 247, 244, 126, 153, 253, 250, 123, 43, 152, 249 > > 23, 208, 246, 179, 87, 212, 252, 183, 89, 245, 248, > > 180, 207, 251, 254, 184, 211, 210, 249, 181, 88 > > 24, 246, 150, 72, 179, 252, 154, 74, 183, 247, 151, > > 178, 248, 253, 155, 182, 254, 249, 152, 73, 181 > > 25, 51, 125, 252, 212, 49, 129, 258, 216, 124, 250, > > 251, 213, 128, 256, 257, 217, 50, 127, 255, 214 > > 26, 125, 44, 154, 252, 129, 46, 158, 258, 126, 153, > > 253, 250, 130, 157, 259, 256, 127, 45, 156, 255 > > 27, 212, 252, 183, 89, 216, 258, 187, 91, 251, 254, > > 184, 211, 257, 260, 188, 215, 214, 255, 185, 90 > > 28, 252, 154, 74, 183, 258, 158, 76, 187, 253, 155, > > 182, 254, 259, 159, 186, 260, 255, 156, 75, 185 > > 29, 49, 129, 258, 216, 5, 22, 100, 31, 128, 256, > > 257, 217, 21, 98, 99, 32, 48, 131, 261, 218 > > 30, 129, 46, 158, 258, 22, 6, 25, 100, 130, 157, > > 259, 256, 23, 24, 101, 98, 131, 47, 160, 261 > > 31, 216, 258, 187, 91, 31, 100, 28, 8, 257, 260, > > 188, 215, 99, 102, 29, 30, 218, 261, 189, 92 > > 32, 258, 158, 76, 187, 100, 25, 7, 28, 259, 159, > > 186, 260, 101, 26, 27, 102, 261, 160, 77, 189 > > \*NSET, NSET=CN7 > > 97, 96, 95, 94, 93, 20, 19, 18, 17, 16, 15, > > 14, 13, 12, 11, 10, 9, 4, 3, 2, 1 > > \*BOUNDARY > > CN7,3,3 > > 1,1,2 > > 2,2,2 > > \*ELSET,ELSET=EALL,GENERATE > > 1,32 > > \*NSET,NSET=NALL,GENERATE > > 1,261 > > \*MATERIAL,NAME=HY > > \*HYPERFOAM,N=2 > > 0.164861,8.88413,2.302e-5,-4.81798,0.,0. > > \*\*SOLID SECTION,ELSET=EALL,MATERIAL=HY > > \*Material, Name=Latexschaum > > \*HYPERFOAM, N=1 > > 0.02, 3.0, 0.05 > > \*SOLID SECTION,ELSET=EALL,MATERIAL=Latexschaum > > \*NSET,NSET=LAST > > 5,6,7,8,22,25,28,31,100 > > \*NSET,NSET=GIBO > > 5, > > 6, > > 7, > > 8, > > 21, > > 22, > > 23, > > 24, > > 25, > > 26, > > 27, > > 28, > > 29, > > 30, > > 31, > > 32, > > 98, > > 99, > > 100, > > 101, > > 102, > > \*NSET,NSET=N1 > > 100 > > \*NSET,NSET=N2 > > 22,25,28,31 > > \*NSET,NSET=N3 > > 5,6,7,8 > > \*NSET,NSET=N4 > > 21,23,24,26,27,29,30,32 > > \*NSET,NSET=N5 > > 98,99,101,102 > > \*STEP,NLGEOM,INC=100 > > \*STATIC > > 1.,1. > > \*CLOAD > > N1,3,-0.000833333 > > N2,3,-0.000416666 > > N3,3,-0.000208333 > > N4,3,0.000833333 > > N5,3,0.001666666 > > \*NODE PRINT,NSET=NALL > > U > > \*EL PRINT,ELSET=EALL > > S > > \*Node file > > RF, U > > \*El file > > S, E, NOE > > \*END STEP ---
### 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 23, 2026, 3:26pm UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/14 "2026-09-23T15:26:08Z")
The constants can be mismatched too since they don’t come from any verified source. But the same model runs normally in Abaqus so I treat it as a CalculiX bug. I guess I’ll report it on GitHub then. ---
### Author: ![JuanP74](https://avatars.discourse-cdn.com/v4/letter/j/b5a626/32.png) [@JuanP74](https://calculix.discourse.group/u/JuanP74) #### Post date: [September 23, 2026, 4:41pm UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/15 "2026-09-23T16:41:25Z")
not completely sure is the case yet but might be the explanation (sorry to resort to IA 😅 😅 😅 ), it works and “looks” very well with the proposed change: ![imagen](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/6/670efb996d60a70187cd5ed9fde325e683a0db02.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 23, 2026, 4:47pm UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/16 "2026-09-23T16:47:13Z")
In Abaqus the syntax for N=1 is: ![image](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/5/5a959da7321342f4297de396040fbc6361d816a7.png) The same syntax is used in CalculiX: ![image](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/f/f6d317277a7bad49834ca6944ba7969c64df5d40.png) So both solvers should assume µ\_1 = 0.02, α\_1 = 3.0 and ν\_1 = 0.05. The only question is whether these values make any sense, but Abaqus accepts them, and CalculiX should too. ---
### Author: ![Viertelstein](https://avatars.discourse-cdn.com/v4/letter/v/e47c2d/32.png) [@Viertelstein](https://calculix.discourse.group/u/Viertelstein) #### Post date: [September 24, 2026, 12:00am UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/17 "2026-09-24T00:00:08Z")
I’m attaching as screenshot. As long as this can’t be calculated in CalculiX, my only option is to upload the INP to a cloud computing service (with ABAQUS), right? That gives you 300 free hours. ABAQUS itself is prohibitively expensive. ![issue fem-0001](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/6/621d1bd82bfe1f05a4b1da367cfc6d288d948c8e.jpeg) ![issue fem-0002](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/4/44efdef9283638a0a64abcd09b92524e17de59bf.jpeg) ---
### Author: ![JuanP74](https://avatars.discourse-cdn.com/v4/letter/j/b5a626/32.png) [@JuanP74](https://calculix.discourse.group/u/JuanP74) #### Post date: [September 24, 2026, 6:10am UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/18 "2026-09-24T06:10:50Z")
Are you sure that the best fit with your data is N=1 model? It seems to work pretty well in CCX with N=2. ---
### Author: ![Viertelstein](https://avatars.discourse-cdn.com/v4/letter/v/e47c2d/32.png) [@Viertelstein](https://calculix.discourse.group/u/Viertelstein) #### Post date: [September 24, 2026, 7:03am UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/19 "2026-09-24T07:03:25Z")
![2409 1](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/4/4f7ce0c1f8296cb630883cb936cb056ac99512a5.png) ![2409 4](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/1/1d388cd4c79b3140b1388ae0e8074c4bf7bb3d99.png) ![2409 3](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/b/b1a473e4a1d09404db9b7d0e56f5594b382de4fc.jpeg) ![2409 2](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/a/ae92188c1af1a57b33a2575a51bcb0a07be74e15.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 24, 2026, 7:12am UTC](https://calculix.discourse.group/t/hyperfoam-model-issue/4115/20 "2026-09-24T07:12:45Z")
> [@Viertelstein](#): > > As long as this can’t be calculated in CalculiX, my only option is to upload the INP to a cloud computing service (with ABAQUS), right? Some other options are: - using an equivalent hyperelastic material model - trying with different constants and N=2 - switching to a different open-source solver which supports material models for such hyperelastic foams (e.g., FEBio has some advanced nonlinear elastic models meant primarily for tissue modeling, but maybe there are better options than that) [Next page](https://calculix.discourse.group/t/hyperfoam-model-issue/4115.md?page=2)