# .inp file details

**URL:** <https://prepomax.discourse.group/t/inp-file-details/2019>\
**Category:** General Questions\
**Created:** [September 17, 2024, 3:38pm UTC](https://prepomax.discourse.group/t/inp-file-details/2019 "2024-09-17T15:38:45Z")\
**Posts on this page:** 20\
**Page:** 1

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**Author:** ![ainurritegui](https://avatars.discourse-cdn.com/v4/letter/a/b5a626/32.png) [@ainurritegui](https://prepomax.discourse.group/u/ainurritegui)\
**Post date:** [September 17, 2024, 3:38pm UTC](https://prepomax.discourse.group/t/inp-file-details/2019/1 "2024-09-17T15:38:45Z")

</div>

I am reading the Calculix Input code guide and would like to understand more about how the .inp file is written. Here are some quaestions I have about it. I did a 2D plane stress test:

- What is the meaning on the heading of: `Hash: Qr6Q0FwL` How is this written?
- How is the name of the Aditional sets is generated? I created 2 ref. points. How is there name selected/gven? (ref\_170561/ref\_170562/ref\_170581/ref\_170582)  
 ![image](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/4/4033fda38592381852accb6140e0292b7fa25e48.png)
- Thse 2 Nset and Eset generate when I select 2 contact pair surfaces, thus I imagine that both refer to the same surface one being the sets of nodes and the other being the set of elements in that surface??  
 ![image](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/9/945528e6fe1c76d48df9e0ff8c15b22065ae9acf.png)
- Then in the surfaces, the S3 and S1 have any special meaning?  
 ![image](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/c/c18d41c5f1d888fe6991e22f6bd393511f7854ae.png)
- When defining the constraints, why do I need to have 2 nodes placed in the same position with different index (17057 and 17058 are in (0,0) position), to say the reference node and the rotation node? These generated extra Nsets, and makes extrange things in the BC definitions also…  
may I just erase the Rot node??  
 ![image](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/c/c465c71d8f1a747607050a69c46f96f6863c3372.png)  
 ![image](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/0/08bb409b9972538e0309b091ffded68fc7978d47.png)

Thank you very very much for your help!

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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:** [September 17, 2024, 5:10pm UTC](https://prepomax.discourse.group/t/inp-file-details/2019/2 "2024-09-17T17:10:34Z")

</div>

> [@ainurritegui](#):
>
> What is the meaning on the heading of: `Hash: Qr6Q0FwL` How is this written?

Apparently, it’s generated by `GetRandomString(8)` function. Of course, you don’t have to include it in your input files, the whole `*HEADING` is optional.

> [@ainurritegui](#):
>
> How is the name of the Aditional sets is generated? I created 2 ref. points. How is there name selected/gven? (ref\_170561/ref\_170562/ref\_170581/ref\_170582)

It’s just the last mesh node number + 1 for REF NODE and +1 again for ROT NODE. Then it continues with increments of 1 for further reference points.

> [@ainurritegui](#):
>
> Thse 2 Nset and Eset generate when I select 2 contact pair surfaces, thus I imagine that both refer to the same surface one being the sets of nodes and the other being the set of elements in that surface??

Yes, those are internal node and element sets generated for your manual selection. Abaqus also converts so-called geometrical sets to node/elements sets when writing an input file.

> [@ainurritegui](#):
>
> Then in the surfaces, the S3 and S1 have any special meaning?

Yes, those are the labels including numbers of element faces. Check the `*SURFACE` keyword in the CalculiX manual.

> [@ainurritegui](#):
>
> When defining the constraints, why do I need to have 2 nodes placed in the same position with different index (17057 and 17058 are in (0,0) position), to say the reference node and the rotation node? These generated extra Nsets, and makes extrange things in the BC definitions also…  
> may I just erase the Rot node??

That’s just what CalculiX’s syntax for `*RIGID BODY` requires:

> For the rotational degrees of freedom a dummy rotational node is used whose translational degrees of freedom are interpreted as the rotations about the reference node. Thus, the first degree of freedom is used as the rotation about the x-axis of the rigid body, the second as the the rotation about the y-axis and the third as the rotation about the z-axis. The rotational node can be defined explicitly using the parameter ROT NODE. In that case, this node must be been assigned coordinates (their value is irrelevant) and should not belong to any element of the structure. In the absence of any of the parameters REF NODE or ROT NODE, extra nodes are generated internally assuming their tasks. The position of the default REF NODE is the origin.

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<div class="post-metadata">

**Author:** ![ainurritegui](https://avatars.discourse-cdn.com/v4/letter/a/b5a626/32.png) [@ainurritegui](https://prepomax.discourse.group/u/ainurritegui)\
**Post date:** [September 18, 2024, 7:54am UTC](https://prepomax.discourse.group/t/inp-file-details/2019/3 "2024-09-18T07:54:10Z")

</div>

Thank you very much for your pront response @FEAnalyst . Just a couple of doubts athat arise from your answers:

> [@FEAnalyst](#):
>
> It’s just the last mesh node number + 1 for REF NODE and +1 again for ROT NODE. Then it continues with increments of 1 for further reference points.

I do not understand. Because in that case the 2nd ref point Nset should be 170563 and not 170581. Moreover when you say _the last mesh node number_ … I have 31017 nodes in my model so I do not know where these 170561 and 170581 come from…

> [@FEAnalyst](#):
>
> Yes, those are the labels including numbers of element faces. Check the `*SURFACE` keyword in the CalculiX manual.

I checked the maual as you suggested, but do not understand how is the numbering ,which is the logic or how do I know which is the right number to put?  
In my case this is the mesh I have and type of analysis, however how do I know which of the 3 options is the right one? how can I know which surface of the element correponds to each number?

 ![image](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/a/a8337dc00b477a67f2ee4c9b0136c6c673cbf50c.png)

> [@FEAnalyst](#):
>
> That’s just what CalculiX’s syntax for `*RIGID BODY` requires:

Right, so from what I understood I need to generate and extra ode at the same place to define as the ROT\_Node and use it to apply the moment there.

Thank you very much!!

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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:** [September 18, 2024, 8:07am UTC](https://prepomax.discourse.group/t/inp-file-details/2019/4 "2024-09-18T08:07:34Z")

</div>

> [@ainurritegui](#):
>
> I have 31017 nodes in my model so I do not know where these 170561 and 170581 come from…

Maybe you have some additional nodes from other features. Just check the \*NODE section of the input file (in keyword editor or after exporting). You should have your mesh nodes and then at the end the two nodes for REF NODE and ROT NODE. Like the last two here with coordinates (1,2,3) to find them easily:

![nodes](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/2/2c7a71efc7c4e9227c08ff148909145958807d05.png)

> [@ainurritegui](#):
>
> I checked the maual as you suggested, but do not understand how is the numbering ,which is the logic or how do I know which is the right number to put?  
> In my case this is the mesh I have and type of analysis, however how do I know which of the 3 options is the right one? how can I know which surface of the element correponds to each number?

It’s based on node numbering. But it’s usually handled by preprocessors as it would be hard to do it manually for 3D elements. You would have to identify the node numbers for a given face, check the definition of the element and compare with numbering in the documentation. I recently explained it here: [Export .inp mesh with node sets - Page 2 - FreeCAD Forum](https://forum.freecad.org/viewtopic.php?t=89234&start=10#p779787)

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**Author:** ![ainurritegui](https://avatars.discourse-cdn.com/v4/letter/a/b5a626/32.png) [@ainurritegui](https://prepomax.discourse.group/u/ainurritegui)\
**Post date:** [September 18, 2024, 9:03am UTC](https://prepomax.discourse.group/t/inp-file-details/2019/5 "2024-09-18T09:03:19Z")

</div>

Pefect that was clear for me now! I have node numbering and deduced which are the face numbers contacting!  
Thank you so much!

However, I am getting an error while inporting my file .inp which I am not able to solve. Can you tell me with what is linked?

 ![image](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/6/608323b35c0cb15ecfbc20447cc559ae1052ad08.png)

Just in case you want to check this is the .inp file  
[Prueba\_calculix.inp](https://prepomax.discourse.group/uploads/short-url/t8L6VSvbgabbSE6FnWyveBZilSU.inp) (305.7 KB)

Thank you very much!

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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:** [September 18, 2024, 9:10am UTC](https://prepomax.discourse.group/t/inp-file-details/2019/6 "2024-09-18T09:10:44Z")

</div>

Which version of PrePoMax are you using ? The input file importer is outdated by it works for me in 2.1.0 and 2.1.10. You may just have to redefine some features that were not recognized properly by the importer.

But since you have the whole input deck, why don’t you submit it using standalone CalculiX outside of PrePoMax ? You will just have to correct this:

```auto
 *ERROR in splitline: there should not
        be more than 16 entries in a
        line;
1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,

```

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<div class="post-metadata">

**Author:** ![ainurritegui](https://avatars.discourse-cdn.com/v4/letter/a/b5a626/32.png) [@ainurritegui](https://prepomax.discourse.group/u/ainurritegui)\
**Post date:** [September 18, 2024, 9:25am UTC](https://prepomax.discourse.group/t/inp-file-details/2019/7 "2024-09-18T09:25:14Z")

</div>

I was using version downloaded: 11th of september. I rechecked and downloaded the one from 13th of september now. SO will try with that one as soon as I can.

I corercted the fact that I had 20 entries. But appeared 1 new error and thousands of warnings.  
I am worried about the one of surface behaviour. Why is this warning appearing?  
SInce I have so many warning I cannot see where the error is coming from.

 ![image](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/f/fa10861a66b11314fd0513a1f11bc8cc5eb61193.png)  
Is there any other way from where I can check where is the rrror coming from?

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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:** [September 18, 2024, 9:32am UTC](https://prepomax.discourse.group/t/inp-file-details/2019/8 "2024-09-18T09:32:30Z")

</div>

Did you correct all the node/element set definitions ? There’s a maximum number of 16 entries per data line. If you scroll up in the command window, you may see more \*ERROR messages.

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**Author:** ![ainurritegui](https://avatars.discourse-cdn.com/v4/letter/a/b5a626/32.png) [@ainurritegui](https://prepomax.discourse.group/u/ainurritegui)\
**Post date:** [September 18, 2024, 10:03am UTC](https://prepomax.discourse.group/t/inp-file-details/2019/9 "2024-09-18T10:03:34Z")

</div>

yes! I checked that. I have no more than 16 entries.  
Scrolling up I do not reach to errors… i have too many warnings

I found something different too:  
Is inportant not to have a comma at the end of the sets?

 ![image](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/f/fec72cab43f80c059547954826380c010863f57f.png)

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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:** [September 18, 2024, 10:23am UTC](https://prepomax.discourse.group/t/inp-file-details/2019/10 "2024-09-18T10:23:57Z")

</div>

The comma shouldn’t be a problem. Here’s what PrePoMax defines:

![ppm set](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/4/4de9211327ab89569090ca009c6275b56e69792e.png)

If you only have this generic error message at the end, can you share the modified input file ?

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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:** [September 18, 2024, 12:31pm UTC](https://prepomax.discourse.group/t/inp-file-details/2019/11 "2024-09-18T12:31:53Z")

</div>

> [@ainurritegui](#):
>
> Is there any other way from where I can check where is the rrror coming from?

You can force the output of any program to go to a file instead of going to the command line if you add:

> \> outputFile.txt

to the end of your command. Then you will get all the lines of the output.

---

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**Author:** ![ainurritegui](https://avatars.discourse-cdn.com/v4/letter/a/b5a626/32.png) [@ainurritegui](https://prepomax.discourse.group/u/ainurritegui)\
**Post date:** [September 18, 2024, 12:43pm UTC](https://prepomax.discourse.group/t/inp-file-details/2019/12 "2024-09-18T12:43:25Z")

</div>

I found another comma where it should not.

 ![image](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/4/4902b11561d8bd9ec8ee036e1ec4e892fdead611.png)  
This is what is showing now:  
 ![image](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/c/cffe6428b945c8ef238fc2704f68b443b40098ec.png)

Here is the .inp file:  
[Prueba\_calculix.inp](https://prepomax.discourse.group/uploads/short-url/nQXOC2j78cMxNOe0DeidwkjPNxM.inp) (305.7 KB)

I wrote outputfile.txt, a .txt file should be generated when runned? or which is the extension of the file i should check to know about the error informatio?

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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:** [September 18, 2024, 12:51pm UTC](https://prepomax.discourse.group/t/inp-file-details/2019/13 "2024-09-18T12:51:43Z")

</div>

Elements of the rack have opposite normals (facing in the negative Z direction). All normals must be positive in 2D analysis.

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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:** [September 18, 2024, 2:31pm UTC](https://prepomax.discourse.group/t/inp-file-details/2019/14 "2024-09-18T14:31:40Z")

</div>

> [@ainurritegui](#):
>
> I wrote outputfile.txt, a .txt file should be generated when runned?

Yes, but you should run the entire command and add a symbol \> at the end with the output file name. You can choose any extension. The file can later be opened in a txt editor.

> Calculix.exe inputFile \> outputFile.txt

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**Author:** ![ainurritegui](https://avatars.discourse-cdn.com/v4/letter/a/b5a626/32.png) [@ainurritegui](https://prepomax.discourse.group/u/ainurritegui)\
**Post date:** [September 19, 2024, 2:00pm UTC](https://prepomax.discourse.group/t/inp-file-details/2019/15 "2024-09-19T14:00:05Z")

</div>

Is it posible that the node numberng order is different in calculix than in other programs?  
A counterclokwise numbering of nodes in a quadrilateral element should give a positive normal, right?

The problm is that I tried numbering them counterclokise and clockwise and gives the same error in both…

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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:** [September 19, 2024, 2:06pm UTC](https://prepomax.discourse.group/t/inp-file-details/2019/16 "2024-09-19T14:06:50Z")

</div>

The positive normal is given by the right-hand rule going around the nodes in the order in which they appear in the element definition. So yes, it should be counterclockwise for 2D elements. From what I checked before, the bottom part (rack) had it opposite in the file you shared. The top one (gear) was ok.

---

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**Author:** ![ainurritegui](https://avatars.discourse-cdn.com/v4/letter/a/b5a626/32.png) [@ainurritegui](https://prepomax.discourse.group/u/ainurritegui)\
**Post date:** [September 19, 2024, 2:14pm UTC](https://prepomax.discourse.group/t/inp-file-details/2019/17 "2024-09-19T14:14:34Z")

</div>

I know… but I changed it and do not understand what is happening…  
[Prueba\_calculix\_v2.inp](https://prepomax.discourse.group/uploads/short-url/iTHdMFCkRjlmJpSP8vbmirCsccJ.inp) (229.1 KB)

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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:** [September 19, 2024, 2:37pm UTC](https://prepomax.discourse.group/t/inp-file-details/2019/18 "2024-09-19T14:37:58Z")

</div>

This time it’s a different issue - node adjustment in contact. Just remove the Adjust parameter and it will work. It may fail to converge but that’s another issue - try without the applied moment (use only small rotation of the rack reference point) and fix the rotation of the gear for now. Contact definition may also need some corrections.

---

<div class="post-metadata">

**Author:** ![ainurritegui](https://avatars.discourse-cdn.com/v4/letter/a/b5a626/32.png) [@ainurritegui](https://prepomax.discourse.group/u/ainurritegui)\
**Post date:** [September 19, 2024, 3:13pm UTC](https://prepomax.discourse.group/t/inp-file-details/2019/19 "2024-09-19T15:13:16Z")

</div>

From your message I understood I should delete the Adjust parameter in the contact pair definition, right?

 ![image](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/6/6af99c543a2b9f81ad3813492bf1bfcb86f95b85.png)

I runned the file and still get the same error:  
 ![image](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/b/bba582065043765257c8b12a7f7afca7cd240b82.png)

[Prueba\_calculix\_v2.inp](https://prepomax.discourse.group/uploads/short-url/vuLVToToZsavGopeJPHnnWsqcv5.inp) (229.1 KB)

---

<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:** [September 19, 2024, 4:43pm UTC](https://prepomax.discourse.group/t/inp-file-details/2019/20 "2024-09-19T16:43:34Z")

</div>

> [@ainurritegui](#):
>
> From your message I understood I should delete the Adjust parameter in the contact pair definition, right?

Yes, when I delete it from your file shared 2 hours ago, it runs normally using ccx 2.22 with PaStiX.

[test.inp](https://prepomax.discourse.group/uploads/short-url/kJRujpfyd2wrqwvxEbMoZV3r2Za.inp) (229.1 KB)

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