# Add\_sm\_st: coefficient should be 0

**URL:** <https://prepomax.discourse.group/t/add-sm-st-coefficient-should-be-0/1680>\
**Category:** General Questions\
**Created:** [April 16, 2024, 2:51pm UTC](https://prepomax.discourse.group/t/add-sm-st-coefficient-should-be-0/1680 "2024-04-16T14:51:58Z")\
**Posts on this page:** 1\
**Showing post:** 2

<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:** [April 16, 2024, 4:59pm UTC](https://prepomax.discourse.group/t/add-sm-st-coefficient-should-be-0/1680/2 "2024-04-16T16:59:25Z")

</div>

Well, it’s still the same problem: [Error creating a section - #5 by FEAnalyst](https://prepomax.discourse.group/t/error-creating-a-section/1656/5)

First of all, add BCs to the unconstrained directions of the rotor. Then try with prescribed rotational BC instead of a moment. At least to establish contact and get rid of initial rigid body motions. But you should consider approaches like using compression-only constraint, springs or non-shell stoppers tied to the rotor.

Yes, the direction of rotation can be determined using the right-hand rule.

---

_[View the full topic](https://prepomax.discourse.group/t/add-sm-st-coefficient-should-be-0/1680)._