Dear Egor,
Some mixed element are already implemented in Getfem++. An exemple of utilisation is in the file
contrib/mixed_elastostatics/mixed_elastostatic.cc
of the distribution. The first step to implement new elements is to define them at the reference element level. For intrinsic vectorial element, you can take example on the RT0 element which is defined in the file getfem_fem.cc (line 1107). As this kind of element is not "affine equivalent" you have to use the post-transformation matrix (P1_RT0_::mat_trans method for the RT0) which allows a supplementary linear transformation which is real element dependant. See the documentation at the page:
http://download.gna.org/getfem/html/homepage/project/femdesc.html#finite-element-methods-description
Yves.
Le 13/06/2013 12:56, Egor Vtorushin a écrit :
Dear YvesI've used Getfem++ some years ago and since that moment i'm thinking that this library does pretty much cover FEA needs.
Right know i'm solving some dynamic elasticity problem with redundant requirements of strain smoothness. The decision has been made to proceed with mixed elements solution when strains are from H_div space and velocities are from L2. It led me to strains approximations that looks like this(mostly i took it from BECACHE, JOLY, TSOGKA 1999 year work)
(same pic attached)
It looks like something in the middle between RTQ1 and QK(2,1) i think.Could you please provide me with a hint how to start implementing this. I've searched the mail-list but was not able to find good materials could help me
Thank you,Egor Vtorushin | ScientistBaker Hughes | Novosibisk Technology Center | Int. Research for Drilling & Evaluations
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