# Stress files and FATLAB

**URL:** <https://calculix.discourse.group/t/stress-files-and-fatlab/2195>\
**Category:** Uncategorized\
**Created:** [April 4, 2024, 2:46am UTC](https://calculix.discourse.group/t/stress-files-and-fatlab/2195 "2024-04-04T02:46:25Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Lt72884](https://avatars.discourse-cdn.com/v4/letter/l/97f17d/32.png) [@Lt72884](https://calculix.discourse.group/u/Lt72884)\
**Post date:** [April 4, 2024, 2:46am UTC](https://calculix.discourse.group/t/stress-files-and-fatlab/2195/1 "2024-04-04T02:46:25Z")

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Ok, i have been emailing the developer of FATLAB and he siad the following:

“In order to use Fatlab, you need to setup and solve an FE model in another program. The mesh is not enough – you need also “stress files” containing the nodal stresses (all 6 stress components) at unit load – one of these files for each load on the model.”

I have been able to solve a basic FEA example of a 65 meter blade in Prepomax, but i am not sure of these stress files.

thanks

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**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:** [April 4, 2024, 6:52am UTC](https://calculix.discourse.group/t/stress-files-and-fatlab/2195/2 "2024-04-04T06:52:51Z")

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This is just about the CalculiX results files (.frd): [Wind turbine hub calculation in Fatlab (PrePoMax results) – fatigue.pro](https://fatigue.pro/2023/02/wind-turbine-hub-calculation-in-fatlab-prepomax-results/)

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**Author:** ![Lt72884](https://avatars.discourse-cdn.com/v4/letter/l/97f17d/32.png) [@Lt72884](https://calculix.discourse.group/u/Lt72884)\
**Post date:** [April 4, 2024, 3:51pm UTC](https://calculix.discourse.group/t/stress-files-and-fatlab/2195/3 "2024-04-04T15:51:05Z")

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i have read that article a few times, but it does not tell me what these stress files are that i am supposed to use.

Am i supposed to do something in prepomax to create those stress files or are they created automatically whenever i do a basic FEA. IE, in your first video of how to use Prepomax on youtube, will that process create these needed stress files?

Or, do i just feed fatlab the .frd file created by prepomax like the articel?

Basically, i did FEA on a 65 meter blade and im hoping that file has all the needed information for fatlab already haha

thanks

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<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:** [April 4, 2024, 5:17pm UTC](https://calculix.discourse.group/t/stress-files-and-fatlab/2195/4 "2024-04-04T17:17:38Z")

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Submitting an analysis in PrePoMax sends the input file to CalculiX which creates various results and log files. The main one is .frd and you should use it for Fatlab. You can find it in your working directory (can be changed in PrePoMax settings).

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<div class="post-metadata">

**Author:** ![Lt72884](https://avatars.discourse-cdn.com/v4/letter/l/97f17d/32.png) [@Lt72884](https://calculix.discourse.group/u/Lt72884)\
**Post date:** [April 5, 2024, 1:36am UTC](https://calculix.discourse.group/t/stress-files-and-fatlab/2195/5 "2024-04-05T01:36:19Z")

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ok, ill give that a go. Thanks for all the help.