# Weld calculation using shell model

**URL:** <https://prepomax.discourse.group/t/weld-calculation-using-shell-model/2810>\
**Category:** General Questions\
**Created:** [June 30, 2025, 2:27pm UTC](https://prepomax.discourse.group/t/weld-calculation-using-shell-model/2810 "2025-06-30T14:27:59Z")\
**Posts on this page:** 4\
**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:** [June 30, 2025, 2:28pm UTC](https://prepomax.discourse.group/t/weld-calculation-using-shell-model/2810/1 "2025-06-30T14:28:00Z")

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Hi All,  
I have a little problem with a simple model that I created to simulate two plates welded together.

 ![Cattura](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/1/11e77ad82d2f990018c969412933fe8710a7099f.png)

The model is made by a horizontal plate that is welded with a vertical plate by a weld (triangular shape in the model).  
I did a compound of the three shell element; I applied a surface traction onthe vertical plate a fixed the extremities of the horizontal plate.  
I applied control node in both the side of the weld, because I need to extract the reaction forces.

This is the message that appear when I try to run the calculation:

 ![Cattura2](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/a/aa180ae3cdfb77b17f8f5758c38c27a372d128dd.png)

Do you have an idea where I did the mistake?

WBR

Marco F.

[Prova\_giunto\_saldato.pmx](https://prepomax.discourse.group/uploads/short-url/odK3J2JI1QaJJ0vZg99Jm2fxVaH.pmx) (162.1 KB)

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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:** [June 30, 2025, 2:30pm UTC](https://prepomax.discourse.group/t/weld-calculation-using-shell-model/2810/2 "2025-06-30T14:30:57Z")

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Since it’s a 2D plane stress model, you have to use a solid, not shell section for it.

Also, flip the normals of the top faces:

 ![normals](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/5/5d8b0a561fb351a64ef6a348d312cf0f4c45df37.png)

and replace Fixed BC with Displacement/Rotation one to avoid further errors.

[Prova\_giunto\_saldato\_mod.pmx](https://prepomax.discourse.group/uploads/short-url/9W1oZc5FFxJWAVpoTRELg9eaY14.pmx) (162.1 KB)

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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:** [June 30, 2025, 2:46pm UTC](https://prepomax.discourse.group/t/weld-calculation-using-shell-model/2810/3 "2025-06-30T14:46:40Z")

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Thank you very much for your help 🤩

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**Author:** ![Paul18fr](https://avatars.discourse-cdn.com/v4/letter/p/35a633/32.png) [@Paul18fr](https://prepomax.discourse.group/u/Paul18fr)\
**Post date:** [June 30, 2025, 3:12pm UTC](https://prepomax.discourse.group/t/weld-calculation-using-shell-model/2810/4 "2025-06-30T15:12:02Z")

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I would have a look first to 2D plane **Strain** modelling