# How to give Orthotropic thermal expansion coefficient

**URL:** <https://calculix.discourse.group/t/how-to-give-orthotropic-thermal-expansion-coefficient/1905>\
**Category:** Uncategorized\
**Created:** [November 10, 2023, 5:26pm UTC](https://calculix.discourse.group/t/how-to-give-orthotropic-thermal-expansion-coefficient/1905 "2023-11-10T17:26:13Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Bhavita](https://avatars.discourse-cdn.com/v4/letter/b/b782af/32.png) [@Bhavita](https://calculix.discourse.group/u/Bhavita)\
**Post date:** [November 10, 2023, 5:26pm UTC](https://calculix.discourse.group/t/how-to-give-orthotropic-thermal-expansion-coefficient/1905/1 "2023-11-10T17:26:13Z")

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Hello,

I’m new to CalculiX, and I was wondering if it’s possible to specify an orthotropic thermal expansion coefficient value. If anyone has an example illustrating this, it would be helpful.

Regards,  
Bhavita

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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:** [November 10, 2023, 5:33pm UTC](https://calculix.discourse.group/t/how-to-give-orthotropic-thermal-expansion-coefficient/1905/2 "2023-11-10T17:33:02Z")

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Yes, you can do it this way:

```auto
*EXPANSION, TYPE=ORTHO
α1, α2, α3

```

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<div class="post-metadata">

**Author:** ![Bhavita](https://avatars.discourse-cdn.com/v4/letter/b/b782af/32.png) [@Bhavita](https://calculix.discourse.group/u/Bhavita)\
**Post date:** [November 10, 2023, 5:49pm UTC](https://calculix.discourse.group/t/how-to-give-orthotropic-thermal-expansion-coefficient/1905/3 "2023-11-10T17:49:44Z")

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Hii @Calc_em, I was trying to run inp file (here attaching that file) but after running calculix not getting any result ,not able to figure out what’s the issue can you help in this?  
\*\* Node sets +++++++++++++++++++++++++++++++++++++++++++++++  
\*\*  
\*Nset, Nset=Internal\_Selection-1\_Fixed-1  
1, 2, 5, 6, 9, 15, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30,  
31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46,  
47, 48, 49, 96, 99, 113, 116, 133, 134, 135, 136, 137, 138, 139, 140, 141,  
142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157,  
158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173,  
174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189,  
190, 191, 192, 193, 194, 195  
\*\*  
\*\* Element sets ++++++++++++++++++++++++++++++++++++++++++++  
\*\*  
\*Elset, Elset=Internal\_Selection-1\_Solid\_Section-1  
Solid\_part-1  
\*\*  
\*\* Surfaces ++++++++++++++++++++++++++++++++++++++++++++++++  
\*\*  
\*\*  
\*\* Physical constants ++++++++++++++++++++++++++++++++++++++  
\*\*  
\*\*  
\*\* Materials +++++++++++++++++++++++++++++++++++++++++++++++  
\*\*  
\*Material, Name=Ti64  
\*Density  
4.43E-09  
\*Elastic  
113800, 0.342

\*Expansion, Zero=20  
8.6E-06

\*EXPANSION,ZERO=273.  
12.E-6,373.  
20.E-6,573.

\*\*  
\*\* Sections ++++++++++++++++++++++++++++++++++++++++++++++++  
\*\*  
\*Solid section, Elset=Internal\_Selection-1\_Solid\_Section-1, Material=Ti64  
\*\*  
\*\* Pre-tension sections ++++++++++++++++++++++++++++++++++++  
\*\*  
\*\*  
\*\* Constraints +++++++++++++++++++++++++++++++++++++++++++++  
\*\*  
\*\*  
\*\* Surface interactions ++++++++++++++++++++++++++++++++++++  
\*\*  
\*\*  
\*\* Contact pairs +++++++++++++++++++++++++++++++++++++++++++  
\*\*  
\*\*  
\*\* Amplitudes ++++++++++++++++++++++++++++++++++++++++++++++  
\*\*  
\*\*  
\*\* Initial conditions ++++++++++++++++++++++++++++++++++++++  
\*\*  
\*\*  
\*\* Steps +++++++++++++++++++++++++++++++++++++++++++++++++++  
\*\*  
\*\*  
\*\* Step-1 ++++++++++++++++++++++++++++++++++++++++++++++++++  
\*\*  
\*Step  
\*Static  
\*\*  
\*\* Output frequency ++++++++++++++++++++++++++++++++++++++++  
\*\*  
\*Output, Frequency=1  
\*\*  
\*\* Boundary conditions +++++++++++++++++++++++++++++++++++++  
\*\*  
\*Boundary, op=New  
\*\* Name: Fixed-1  
\*Boundary  
Internal\_Selection-1\_Fixed-1, 1, 6, 0  
\*\*  
\*\* Loads +++++++++++++++++++++++++++++++++++++++++++++++++++  
\*\*  
\*Cload, op=New  
\*Dload, op=New  
\*\*  
\*\* Defined fields ++++++++++++++++++++++++++++++++++++++++++  
\*\*  
\*\*  
\*\* History outputs +++++++++++++++++++++++++++++++++++++++++  
\*\*  
\*\*  
\*\* Field outputs +++++++++++++++++++++++++++++++++++++++++++  
\*\*  
\*Node file  
RF, U  
\*El file  
S, E  
\*\*  
\*\* End step ++++++++++++++++++++++++++++++++++++++++++++++++  
\*\*  
\*End step

Regards,  
Bhavita

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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:** [November 10, 2023, 6:59pm UTC](https://calculix.discourse.group/t/how-to-give-orthotropic-thermal-expansion-coefficient/1905/4 "2023-11-10T18:59:22Z")

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> [@Bhavita](#):
>
> \*Expansion, Zero=20  
> 8.6E-06
> 
> \*EXPANSION,ZERO=273.  
> 12.E-6,373.  
> 20.E-6,573.

Why is it defined twice ?