Learning Forum

[pnoever]

Hey gals and guys,

I am about to build up a beam for a wind turbine blade. I have a cross sectional analysis tool that gives me the 6x6 stiffness and mass matrices of the blade cross sections. These can be extracted for diferent reference systems.

1. A coordinate system of the cross section with in a reference point in the cross section as I define it
2. In the same coordinate system as defined by me but with the origin moved to the elastic center of the cross section (Additional output: location elastic center)
3. In the principal axis system moved to the elastic center of the cross section. (Additional output: location elastic center and angle of principal axes)

Which matrices should I use? And where do I put the element nodes - elastic center or reference point of cross section?

 

I build the cross section in Ansys classic APDL with the below code. Here X1,Y1,Z1 would be the either the reference point or the elastic center of the cross sections. K is the stiffness matrix and M the mass matrix for the composite cross section.

    ! nodes
    N,1,X1,Y1,Z1
    N,2i,X2,Y2,Z2
    
    ! beam properties
    SECTYPE,      1,COMB,MATRIX,    
    CBMX,1,  K(1,1), K(1,2),  K(1,3),  K(1,4),  K(1,5), K(1,6)
    CBMX,2,              K(2,2),  K(2,3),  K(2,4),  K(2,5), K(2,6)
    CBMX,3,                           K(3,3),  K(3,4),  K(3,5), K(3,6)
    CBMX,4,                                        K(4,4),  K(4,5), K(4,6)
    CBMX,5,                                                     K(5,5), K(5,6)
    CBMX,6,                                                                 K(6,6)
    
    CBMD,1,  M(1,1), M(1,2),  M(1,3),  M(1,4),  M(1,5), M(1,6)
    CBMD,2,              M(2,2),  M(2,3),  M(2,4),  M(2,5), M(2,6)
    CBMD,3,                           M(3,3),  M(3,4),  M(3,5), M(3,6)
    CBMD,4,                                        M(4,4),  M(4,5), M(4,6)
    CBMD,5,                                                     M(5,5), M(5,6)
    CBMD,6,                                                                 M(6,6)
    
    ! elements
    SECNUM,1
    E,1,1,2

 

Thank you for your help :)

[Erik Kostson]

 

 

 

Hi

Something slightly different, but perhaps useful.

Please contact support also as there might be some inbuilt tools in Ansys ACP that does this (3D acp -> beam element creation in both APDL and Workbench) especially for these type of applications (complex composite wind turbine blades).

All the best

Erik

 

 

 

[pnoever]

Hi Erik,

thanks for your reply. The problem is first I am working with Ansys classic not with Workbench. And second I am creating and analysing the cross sections and their properties in an external program, which is especially adapted to wind turbine blade cross sections. Therefore, I have already the 6x6 matrices for mass and stiffness and want to part from there with an BEAM,188 model and not bulding my composite cross section with ACP.

However, thanks for your suggestion!

Bests
Pablo

[Erik Kostson]

So this tool will create all the sectype and cbmx matrices automatic (based on geom and lay up in ACP) for beam188 elements in apdl and workbench so it is very powerful.

All the best 

Erik

[pnoever]

Got ya, at least I could use it for comparison or verification. Cause we don't want to leave the flexibility ofthe external program we have incorporated into our workflow.

Thank you.