# Hourglass control

**URL:** <https://calculix.discourse.group/t/hourglass-control/1450>\
**Category:** Uncategorized\
**Created:** [January 19, 2023, 2:03pm UTC](https://calculix.discourse.group/t/hourglass-control/1450 "2023-01-19T14:03:55Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![Disla](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/disla/32/3548_2.png) [@Disla](https://calculix.discourse.group/u/Disla)\
**Post date:** [January 19, 2023, 2:03pm UTC](https://calculix.discourse.group/t/hourglass-control/1450/1 "2023-01-19T14:03:55Z")

</div>

I have read the following comment on a design code:

“Care should be taken when selecting formulations and integration rules. Formulations with (selective) reduced integration rules are less prone to locking effects than full integrated simple elements; however, the reduced integration elements may produce zero energy modes (“hourglassing”) and require hourglass control. When hourglass control is used, the hourglass energy should be monitored and shown to be small compared to the internal energy of the system (typically less than 5%).”

In the manual I can read hourglass control is automatically activated for reduced integration.

¿How could I measure that hourglass energy in CalculiX?

Regards

---

<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:** [January 19, 2023, 2:55pm UTC](https://calculix.discourse.group/t/hourglass-control/1450/2 "2023-01-19T14:55:06Z")

</div>

Abaqus has the ALLAE (artificial strain energy) output variable. Unfortunately, CalculiX doesn’t have it and it seems that the only way is to look for hourglass modes using a scaled deformed shape visualization.

---

<div class="post-metadata">

**Author:** ![Disla](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/disla/32/3548_2.png) [@Disla](https://calculix.discourse.group/u/Disla)\
**Post date:** [January 19, 2023, 3:15pm UTC](https://calculix.discourse.group/t/hourglass-control/1450/3 "2023-01-19T15:15:24Z")

</div>

Thank you very much Cal\_em.

---

<div class="post-metadata">

**Author:** ![xyont](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/xyont/32/3553_2.png) [@xyont](https://calculix.discourse.group/u/xyont)\
**Post date:** [January 20, 2023, 9:56am UTC](https://calculix.discourse.group/t/hourglass-control/1450/4 "2023-01-20T09:56:06Z")

</div>

> [@Calc\_em](#):
>
> Abaqus has the ALLAE (artificial strain energy) output variable.

interesting to know, how good is it compared to mesh refinement of thick curved part or sharp corner and layering trough thickness of thin part?

maybe this is another interesting [implementation](https://calculix.discourse.group/t/c3d8i-element-in-calculix/792) were not yet approved and published.