[MBDyn-users] Placing the middle node of a 3 node beam -> for using AeroDyn

Pierangelo Masarati masarati at aero.polimi.it
Wed Feb 23 15:32:00 CET 2011


Jens.vanSchelve at Emerson.com wrote:
> -----------------------------------
> Pierangelo wrote:
> -----------------------------------
> In my opinion, you should decouple the structural and the aerodynamic
> models.  You need to place structural nodes where AeroDyn expects them,
> and connect them by beam elements.  The last half aerodynamic patch from
> the last node to the blade tip will have no structural modeling, but
> that's not an issue, as soon as you model inertia correctly (the
> flexibility of the extremity should not be an issue).
> 
> Reworking to interface module to pass AeroDyn the average velocity
> between two nodes and split the resulting forces accordingly sounds a
> bit too intrusive and I do not expect significant improvements from it. 
>   I admit it could have been a valid design choice from the beginning,
> although more complex than the one we chose.
> 
> Cheers, p.
> -----------------------------------
> 
> 
> So this option
> 
>        ___A___ ___B___ ___C___ 
>  ---  |       |       |       | 
> (HUB) 1---2-------3-------4---5
>  ---  |_______|_______|_______|
> 
> 
> But would you suggest (for this example) option
> 1. Using two beam3 elements (1-3,3-5) with the issue having node 2 at
> 1/3 of beam I and not in the middle or
> 2. Using one beam3 element (2-4) and one (or two) beam2 element to
> connect node 1 and 2 (maybe, not nessesary 4 and 5)

I would do

 >            ___A___ ___B___ ___C___ ___D___
 >  ---      |       |       |       |       |
 > (HUB) 1-------2-------3-------4-------5   |
 >  ---      |_______|_______|_______|_______|

and use 2 beam3 (1-3, 3-5).  As I said, the structural and the 
aerodynamic models can be decoupled.  p.


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