# Traction test with surfaces

**URL:** <https://prepomax.discourse.group/t/traction-test-with-surfaces/3195>\
**Category:** General Questions\
**Created:** [January 15, 2026, 3:23pm UTC](https://prepomax.discourse.group/t/traction-test-with-surfaces/3195 "2026-01-15T15:23:51Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![MarcoMeccAlte](https://avatars.discourse-cdn.com/v4/letter/m/c0e974/32.png) [@MarcoMeccAlte](https://prepomax.discourse.group/u/MarcoMeccAlte)\
**Post date:** [January 15, 2026, 3:23pm UTC](https://prepomax.discourse.group/t/traction-test-with-surfaces/3195/1 "2026-01-15T15:23:51Z")

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Good afternoon All,

I try to made a traction test with two surfaces that (one is fixed and one is in traction):

 ![image](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/2/2cdec8bcc57a35d1712c424427ab0bf3b94a355b.png)

I apply the master/slave contact on the middle of the two geometries; but I’m not able to perform the calclulation:

 ![image](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/9/9b28c8e6c92dddc10a6309ab2e832845f35e4c32.png)

Both thickness are 0.65mm; and the traction force is 100N, as explain in the picture.

I did not put the geometry on compound, because I’m still not fully understand when is necessary to make the compound between two (or more) components.

Is anyone that can help me to understand where I’m making errors?

WBR

Marco F.

[Analisi\_prova\_trazione.pmx](https://prepomax.discourse.group/uploads/short-url/xfNVs1zacSRF2nB89HjJOKCmJ3i.pmx) (1.6 MB)

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**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:** [January 15, 2026, 3:43pm UTC](https://prepomax.discourse.group/t/traction-test-with-surfaces/3195/2 "2026-01-15T15:43:54Z")

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I can’t check the file now, but the error means that you assigned shell section to solid elements (2D or 3D). Is your analysis in 2D model space ?

> [@MarcoMeccAlte](#):
>
> I did not put the geometry on compound, because I’m still not fully understand when is necessary to make the compound between two (or more) components.

Compound is used when you want to merge the parts in such a way that the mesh is continuous (so you can’t define contact to allow for separation or sliding between the parts then).

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<div class="post-metadata">

**Author:** ![MarcoMeccAlte](https://avatars.discourse-cdn.com/v4/letter/m/c0e974/32.png) [@MarcoMeccAlte](https://prepomax.discourse.group/u/MarcoMeccAlte)\
**Post date:** [January 15, 2026, 3:48pm UTC](https://prepomax.discourse.group/t/traction-test-with-surfaces/3195/3 "2026-01-15T15:48:55Z")

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Yes the analysis is set on 2D Plane Stress.

I imported a IGES file with two surfaces; and I think that the sw recognized properly:

 ![image](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/1/183f6b68cf8fa8808afd9d940e0e07b0b6acb33d.png)

 ![image](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/6/60d5dd77a2bdb91a2bfeca5b3314123ca796babb.png)

And this is the selection that I did (for both the surfaces):

 ![image](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/7/7965adfd859e0f4f224f440d39ad84fb1e066e2e.png)

 ![image](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/8/81beeb923c71edd20c54add5652997a80cc76ccf.png)

Am I’m wrong?

WBR

Marco F.

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<div class="post-metadata">

**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:** [January 15, 2026, 3:51pm UTC](https://prepomax.discourse.group/t/traction-test-with-surfaces/3195/4 "2026-01-15T15:51:33Z")

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Then you have to apply solid section instead. Shell section is only used for 3D models with shell elements. Here, you are using plane stress elements whose thickness is defined via solid section.

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<div class="post-metadata">

**Author:** ![MarcoMeccAlte](https://avatars.discourse-cdn.com/v4/letter/m/c0e974/32.png) [@MarcoMeccAlte](https://prepomax.discourse.group/u/MarcoMeccAlte)\
**Post date:** [January 15, 2026, 4:13pm UTC](https://prepomax.discourse.group/t/traction-test-with-surfaces/3195/5 "2026-01-15T16:13:55Z")

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Thank you for the suggestion; I’m not knowing this kind of freature.

Now the simulation is running properly.

Thank you very much for the support.

WBR

Marco F.