# Difference in reactions forces

**URL:** <https://prepomax.discourse.group/t/difference-in-reactions-forces/872>\
**Category:** General Questions\
**Created:** [May 16, 2023, 3:59pm UTC](https://prepomax.discourse.group/t/difference-in-reactions-forces/872 "2023-05-16T15:59:41Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Michal](https://avatars.discourse-cdn.com/v4/letter/m/34f0e0/32.png) [@Michal](https://prepomax.discourse.group/u/Michal)\
**Post date:** [May 16, 2023, 3:59pm UTC](https://prepomax.discourse.group/t/difference-in-reactions-forces/872/1 "2023-05-16T15:59:41Z")

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I have general question:  
how big difference can be in value of reactions/supports between different software computations and also between “hand calculations” and fea results  
thanks in advance for reply

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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:** [May 16, 2023, 4:40pm UTC](https://prepomax.discourse.group/t/difference-in-reactions-forces/872/2 "2023-05-16T16:40:40Z")

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It depends on the problem but reaction forces are often highly predictable and you can get accurate analytical results with proper FBD. The difference between various software shouldn’t be significant if the same model is analyzed. Keep in mind that CalculiX reports reaction forces as total forces (including applied load if there is any for a given node).

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**Author:** ![VIR](https://avatars.discourse-cdn.com/v4/letter/v/9d8465/32.png) [@VIR](https://prepomax.discourse.group/u/VIR)\
**Post date:** [May 23, 2023, 6:38am UTC](https://prepomax.discourse.group/t/difference-in-reactions-forces/872/3 "2023-05-23T06:38:43Z")

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> [@FEAnalyst](#):
>
> Keep in mind that CalculiX reports reaction forces as total forces (including applied load if there is any for a given node).

I applied a displacement on a surface through a point constrained by a rigid body. The purpose was to obtain the applied force on that point for the displacement to be done. Unfortunately, the output forces are not my expected values.

Do you know if your sentence is in any way related to this ?

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**Author:** ![Michal](https://avatars.discourse-cdn.com/v4/letter/m/34f0e0/32.png) [@Michal](https://prepomax.discourse.group/u/Michal)\
**Post date:** [May 23, 2023, 6:51am UTC](https://prepomax.discourse.group/t/difference-in-reactions-forces/872/4 "2023-05-23T06:51:56Z")

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thanks a lot it is useful  
best regards

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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:** [May 23, 2023, 6:55am UTC](https://prepomax.discourse.group/t/difference-in-reactions-forces/872/5 "2023-05-23T06:55:17Z")

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> [@VIR](#):
>
> Do you know if your sentence is in any way related to this ?

No, this is only relevant in cases when forces are applied to nodes from which you read the RF values.