# Shear force(x) at the tower base

**URL:** <https://forums.nlr.gov/t/shear-force-x-at-the-tower-base/245>\
**Category:** Computer-Aided Engineering Software Tools\
**Created:** [April 23, 2010, 1:37pm UTC](https://forums.nlr.gov/t/shear-force-x-at-the-tower-base/245 "2010-04-23T13:37:09Z")\
**Posts on this page:** 1\
**Showing post:** 1

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**Author:** ![Yinping.Yang](https://avatars.discourse-cdn.com/v4/letter/y/b487fb/32.png) [@Yinping.Yang](https://forums.nlr.gov/u/Yinping.Yang)\
**Post date:** [April 23, 2010, 1:37pm UTC](https://forums.nlr.gov/t/shear-force-x-at-the-tower-base/245/1 "2010-04-23T13:37:09Z")

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Hi,

I simulate the model under a linear increasing wind case. From the results comparison, I found the shear force in x axis at the tower base is different between FAST and Bladed. In contrast, the shear force in x axis at the tower top agrees well. Could someone give me some hints? I suspect maybe the tower leads to this problem? The yaw motion is disabled.

I do not understand what yields the moment about z axis at the tower top/base. The thrust on the rotor is not equally distributed, so there is a torque about z axis. Am I correct?

Thanks  
Best regards

Yinping Yang

 ![Power.jpg](https://europe1.discourse-cdn.com/nrel/original/1X/c51e0ca637e82bb71daecbb260b757fbf7603b6c.jpeg)  
 ![ShearTowrBase.jpg](https://europe1.discourse-cdn.com/nrel/original/1X/3dcd9b4acde7f4d41b1c029830cdc623354566e9.jpeg)  
 ![MomentTowerBase.jpg](https://europe1.discourse-cdn.com/nrel/original/1X/75ba2f342be58c01a223fea86f4c906fef0fa809.jpeg)

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