Application of FAST output for static and fatigue FEA run

Wind & Water Computer-Aided Engineering Software Tools
1

Hi

I have run the FAST simulation for Test18 (NREL 5 MW land based 63 m turbine). I want to use the output loads and moments into an FEA tool. We have below output from FAST for the spanwise loads

Spn1MLxb1 to Spn5MLxb1 (local edgewise moments for station 1 to 5)
Spn1MLyb1 to Spn5MLyb1 (local flapwise moments for station 1 to 5)
Spn1MLzb1 to Spn5MLzb1 (local pitching moments for station 1 to 5)

Query 1: Where are these stations located along the 61.5 m blade span?. Is there any fig/table showing the coordinates to apply these forces?

Query 2: In general is there a guidance on carrying below parameters from FAST run to commercial FEA tools like Ansys/Abaqus?

RootFxc1,RootFyc1,RootFzc1 out-of-plane shear, in-plane shear and axial force at blade-1 root
RootFxc2,RootFyc2,RootFzc2 out-of-plane shear, in-plane shear and axial force at blade-2 root
RootFxc3,RootFyc3,RootFzc3 out-of-plane shear, in-plane shear and axial force at blade-3 root

RootMxc1,RootMyc1,RootMzc1 in-plane moment, out-of-plane moment and pitching moment at blade-1 root
RootMxc2,RootMyc2,RootMzc2 in-plane moment, out-of-plane moment and pitching moment at blade-1 root
RootMxc3,RootMyc3,RootMzc3 in-plane moment, out-of-plane moment and pitching moment at blade-1 root

RootMxb1, RootMyb1 - Blade 1 edgewise and flapwise moments at root
RootMxb2, RootMyb2 - Blade 2 edgewise and flapwise moments at root
RootMxb3, RootMyb3 - Blade 3 edgewise and flapwise moments at root

-Best Regards
Pravin

2

Dear Pravin,

The spanwise locations of the nodes where the local blade loads (Spn1MLxb1 etc.) are output are described in the old FAST User’s Guide–see the description of BldGagNd. I don’t have a great figure to share, but a description of the local blade coordinate system where the local blade loads are output is given in my Mar 13, 2015 post in the following forum topic: Discrepancy in Loads Between Blade Root and Local Spans.

While a detailed description has not been written, there is some discussion about post-processing FAST results for structural analysis of stress, etc. through FEA in the following forum topics:
Stress analysis of blade.

Best regards,

3

Hi jason
i have a question
i want to know what is the application of loads outputs by FAST in coned coordinate system such as “RootFxc1” or “RootFyc1” in the process of wind turbine design or blade design
and what is the advantage of them compared to the loads on the blade coordinate system

thanks

4

Dear @Ali.Rouhbakhsh,

I’m not sure I fully understand what you are asking, but the coned coordinate system is aligned with the pitch bearing and fixed to the hub, whereas the blade coordinate system is aligned with the pitch bearing and fixed to the blade. So, the former is useful for hub design while the later is used for blade-root design.

Best regards,