Rotating Shafts

Hi,

is it possible to use code-aster to model rotating shafts with gyroscopic effects? I'm sure EDF has turbines and those turbines have eigenmode problems which might require modal and transient analysis.


Any hints where to start?

Cheers, Torsten

Hi,

I am sorry, it seems that EDF buys its turbines, as there are no available model for gyroscopic effects in Code-Aster...

As there is already a quadratic eigenvalue solver in CA, maybe it could be possible to play with matrices to create a Gyroscopic matrix to circumvent the problem... maybe... but this could be also a very interesting development (for example, a 2D axisym gyroscopic element)

hi,

is the keyword \"ROTATION\" (in the \"AFFE_CHAR_MECA\" command) not usefull to model the \"gyroscopic effect\" ? The formula given page 15 of the doc U4.44.01 seems to match my old memory of what this effect was...

AM

Hi,

there are several effects when solving problems for rotating machines:
- the centrifugal acceleration, which is defined by the ROTATION option in AFFE_CHAR_MECA
- but also, when the diameter of the rotating shaft is relatively important, the Coriolis effects may have a non negligible influence, which can be described by an anti-symmetric gyroscopic \"stiffness\" matrix and yields to a quadratic eigenvalue problem.
To my knowledge, this second effect is not implemented in Aster yet.

i would have been very surprised if CA wasn't able to handle such problems (\"EDF seems to buy its turbines\"... \"buy\" implies that replacement isn't free...).

documentation of MODE_ITER_SIMULT (modal analysis), page 5, tells that this command is able to deal with \"dynamic stability of structures with viscous stiffness (and/or quadratic stiffness) and with gyroscopic effect\"

if something isn't clear enough in such studies, i suggest to ask your questions in the forum \"Utilisation de Code-Aster\" on www.code-aster.org (questions in english are welcome even though a large number of threads are in french).

AM