# History Output. unbalanced equilibrium of forces

**URL:** <https://prepomax.discourse.group/t/history-output-unbalanced-equilibrium-of-forces/1294>\
**Category:** Bug Reports\
**Created:** [November 28, 2023, 9:38pm UTC](https://prepomax.discourse.group/t/history-output-unbalanced-equilibrium-of-forces/1294 "2023-11-28T21:38:37Z")\
**Posts on this page:** 9\
**Page:** 1

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**Author:** ![ANYS](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/anys/32/7737_2.png) [@ANYS](https://prepomax.discourse.group/u/ANYS)\
**Post date:** [November 28, 2023, 9:38pm UTC](https://prepomax.discourse.group/t/history-output-unbalanced-equilibrium-of-forces/1294/1 "2023-11-28T21:38:37Z")

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When I request the total reaction force on the base of a Surface Spring Support, the result is unbalanced. There are 25.000N missing in this particular case.

 ![imagen](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/9/9e74fc3bceaeecd9169e16cf8f2bffc967a83acf.png)  
 ![imagen](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/c/c9da46c405b99c41864ad987966c3490ba93f285.png)

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**Author:** ![synt](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/synt/32/4658_2.png) [@synt](https://prepomax.discourse.group/u/synt)\
**Post date:** [November 29, 2023, 5:57am UTC](https://prepomax.discourse.group/t/history-output-unbalanced-equilibrium-of-forces/1294/2 "2023-11-29T05:57:04Z")

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it seems not a bug, there’s no boundary support and dof’s restrained at node of spring element. Probably, reaction force is available when using two node spring element.

in such condition CalculiX provide \*Section print feature to get output force of surface set, unfortunately is not yet implemented in PrePoMax. So, user required to define manually in Edit CalculiX Keywords.

\*edited  
below simple test, results shown model of surface spring is in equilibrium.

 ![2023-11-29 13_40_44-](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/d/de30c3f76e18b4d022adeef2fed52e0ce6e24dcc.png)

 ![2023-11-29 13_24_41-](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/4/4abaa6f22438538749fb1bc3179b27d81189a18c.png)

 ![2023-11-29 13_32_49-Source](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/3/32df82accc1705242c95241d7540ba50cc6d65bd.png)

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**Author:** ![ANYS](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/anys/32/7737_2.png) [@ANYS](https://prepomax.discourse.group/u/ANYS)\
**Post date:** [November 29, 2023, 7:35am UTC](https://prepomax.discourse.group/t/history-output-unbalanced-equilibrium-of-forces/1294/3 "2023-11-29T07:35:41Z")

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Ok.Spring Surface is in balance but RFz of that surface is not available and deliver an empty value. Is that right?  
My 75.000 N corresponds only to the nodes with BC z=0. 👍

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**Author:** ![synt](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/synt/32/4658_2.png) [@synt](https://prepomax.discourse.group/u/synt)\
**Post date:** [November 29, 2023, 7:49am UTC](https://prepomax.discourse.group/t/history-output-unbalanced-equilibrium-of-forces/1294/4 "2023-11-29T07:49:22Z")

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indeed, there’s no reaction force output for unrestrained nodes.

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**Author:** ![Matej](https://avatars.discourse-cdn.com/v4/letter/m/a698b9/32.png) [@Matej](https://prepomax.discourse.group/u/Matej)\
**Post date:** [November 29, 2023, 1:07pm UTC](https://prepomax.discourse.group/t/history-output-unbalanced-equilibrium-of-forces/1294/5 "2023-11-29T13:07:58Z")

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So I see that the \*Section print has some nice usages.

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<div class="post-metadata">

**Author:** ![synt](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/synt/32/4658_2.png) [@synt](https://prepomax.discourse.group/u/synt)\
**Post date:** [November 29, 2023, 1:25pm UTC](https://prepomax.discourse.group/t/history-output-unbalanced-equilibrium-of-forces/1294/6 "2023-11-29T13:25:53Z")

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right, it can be useful to check free-body diagram of complex models. CalculiX will compute internal forces by integration, user only need to partition the model to defining surfaces of solid part.

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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:** [November 29, 2023, 2:16pm UTC](https://prepomax.discourse.group/t/history-output-unbalanced-equilibrium-of-forces/1294/7 "2023-11-29T14:16:00Z")

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Indeed, here’s an old discussion about it: [Section print in history outputs](https://prepomax.discourse.group/t/section-print-in-history-outputs/47)

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**Author:** ![Matej](https://avatars.discourse-cdn.com/v4/letter/m/a698b9/32.png) [@Matej](https://prepomax.discourse.group/u/Matej)\
**Post date:** [December 20, 2023, 7:24pm UTC](https://prepomax.discourse.group/t/history-output-unbalanced-equilibrium-of-forces/1294/8 "2023-12-20T19:24:30Z")

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Since this is not really a PrePoMax bug I will close the topic.

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<div class="post-metadata">

**Author:** ![Matej](https://avatars.discourse-cdn.com/v4/letter/m/a698b9/32.png) [@Matej](https://prepomax.discourse.group/u/Matej)\
**Post date:** [December 20, 2023, 7:24pm UTC](https://prepomax.discourse.group/t/history-output-unbalanced-equilibrium-of-forces/1294/9 "2023-12-20T19:24:33Z")

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