Tuctas wrote:
I hope that some time the titles of the two options of non-linear analysis in Robot will be at last corrected...(this is the only way to stop confusing the users...).
I hope also .... I think many engineer using RSA performed 3rd order analysis without knowing it!
t.sautier, when you say: "2nd order : RSA is updating the efforts only, taking into account the pdelta effect and at each iteration it is starting from non deformed chape (common pdelta effect and that's all)" obviously you mean pDelta effects and not pdelta (actually the correct symbol of these effects is P-Δ, and P-δ respectively, as the come out from the Greek letters).
this big delta and small delta still confuses me ... I meant the effect of creating a moment beause of non centered own weight due to deformation. I don't remember which delta big or small we are talking about for this effect 🙂
When you say that at each iteration the analysis is starting from non-deformed shape, you mean the deformed shape of the elements and not the deformed shape of the structure (the later is generated because of the displaced nodes of columns) don't you?
Hummm, I'am not sure what I meant 🙂 as my example was with one element (one bar). In my mind, this applies also to a whole structure : 2nd order ->
For one increment of loading :
iterations
step 1 : RSA calculate deformed shape 1st order,
step 2 : then second step calculates induced moment because of non centered own weight,
step 3 : retstard from non deformed structure and applies ow weight + above moment
step 4 : new deformed shape new moment etc ....
iterates till difference between effort of iteration n-(n-1) < tolerance
Next increment starting from non deformed shape + effort from previous increment.
But Pawel has to confirm 😉
For third order, much more complicated ..... because stress matrix in addition, updating of this matrix, stiffness matrix also updated, the two matrices are linked stiness is inluenced by stresses, .... etc .... I would say that as everything is updated at each iteration, then its like the calculations is made using the deformed shape at each iteration;
But Pawel has to confirm 😉
thanks Pawel for your explanations and look forward if you have news from the development team. But I'm not sure something can be done except choosing another measure of the solution rest .... I keep in mind my this effect happens when structures is made of part of sub structure with a complete or partially independent behavior -> the criterion doesn't detects these difference because it average at the whole structure scale. Maybe we could have the same effect for example with a building with one floor very loose compared to other floor very stiff -> one shall not play with tolerance espacially in this case 🙂
from Robobat wrote me that problem was signed as RM-26704.
. By use of proposed new parametric members there will be max 15 different parametric member types.
