# 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:** 1
**Showing post:** 10

<div class="post-metadata">

### 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")

</div>

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

```

---

_[View the full topic](https://calculix.discourse.group/t/hyperfoam-model-issue/4115)._