# How to get GENERALIZED Mass and STIFFNESS in Modal analysis

**URL:** <https://calculix.discourse.group/t/how-to-get-generalized-mass-and-stiffness-in-modal-analysis/1092>\
**Category:** Uncategorized\
**Created:** [May 7, 2022, 1:38pm UTC](https://calculix.discourse.group/t/how-to-get-generalized-mass-and-stiffness-in-modal-analysis/1092 "2022-05-07T13:38:30Z")\
**Posts on this page:** 7\
**Page:** 1

<div class="post-metadata">

**Author:** ![LiKay](https://avatars.discourse-cdn.com/v4/letter/l/b19c9b/32.png) [@LiKay](https://calculix.discourse.group/u/LiKay)\
**Post date:** [May 7, 2022, 1:38pm UTC](https://calculix.discourse.group/t/how-to-get-generalized-mass-and-stiffness-in-modal-analysis/1092/1 "2022-05-07T13:38:30Z")

</div>

Hi,  
I am trying to perform a simple modal analysis using \*FREQUENCY card with C3D20R element. But I don’t know how to get the generalized mass and stiffness. An example of file.f06 from Nastran is given at the next picture.

 ![1651930587(1)](https://global.discourse-cdn.com/free1/uploads/calculix/original/1X/25fc4f4c249406ac71f8938479e609ab9bfca589.png)  
Do you know how can I get them in Calculix? Thanks.

---

<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:** [May 7, 2022, 4:50pm UTC](https://calculix.discourse.group/t/how-to-get-generalized-mass-and-stiffness-in-modal-analysis/1092/2 "2022-05-07T16:50:37Z")

</div>

The generalized mass will always be 1 since normalization is done using a mass matrix.

---

<div class="post-metadata">

**Author:** ![JuanP74](https://avatars.discourse-cdn.com/v4/letter/j/b5a626/32.png) [@JuanP74](https://calculix.discourse.group/u/JuanP74)\
**Post date:** [May 7, 2022, 4:54pm UTC](https://calculix.discourse.group/t/how-to-get-generalized-mass-and-stiffness-in-modal-analysis/1092/3 "2022-05-07T16:54:05Z")

</div>

![imagen](https://global.discourse-cdn.com/free1/uploads/calculix/original/1X/797052d0e79f44e70324be680e81a1cd73630a78.png)

---

<div class="post-metadata">

**Author:** ![mmartin](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@mmartin](https://calculix.discourse.group/u/mmartin)\
**Post date:** [May 8, 2022, 6:41pm UTC](https://calculix.discourse.group/t/how-to-get-generalized-mass-and-stiffness-in-modal-analysis/1092/4 "2022-05-08T18:41:11Z")

</div>

Within the .dat file.

Manuel

---

<div class="post-metadata">

**Author:** ![LiKay](https://avatars.discourse-cdn.com/v4/letter/l/b19c9b/32.png) [@LiKay](https://calculix.discourse.group/u/LiKay)\
**Post date:** [May 9, 2022, 1:55am UTC](https://calculix.discourse.group/t/how-to-get-generalized-mass-and-stiffness-in-modal-analysis/1092/5 "2022-05-09T01:55:56Z")

</div>

Thanks for your support so much, Juan.

---

<div class="post-metadata">

**Author:** ![LiKay](https://avatars.discourse-cdn.com/v4/letter/l/b19c9b/32.png) [@LiKay](https://calculix.discourse.group/u/LiKay)\
**Post date:** [May 9, 2022, 1:56am UTC](https://calculix.discourse.group/t/how-to-get-generalized-mass-and-stiffness-in-modal-analysis/1092/6 "2022-05-09T01:56:48Z")

</div>

OK, Thank you for pointing this out.

---

<div class="post-metadata">

**Author:** ![LiKay](https://avatars.discourse-cdn.com/v4/letter/l/b19c9b/32.png) [@LiKay](https://calculix.discourse.group/u/LiKay)\
**Post date:** [May 9, 2022, 2:01am UTC](https://calculix.discourse.group/t/how-to-get-generalized-mass-and-stiffness-in-modal-analysis/1092/7 "2022-05-09T02:01:44Z")

</div>

OK, Thank you for your help.