[Getfem-users] 3D truss element

[Roman Putanowicz]

Dear All,

Has anyone of you implemented 3D truss element (or 2D) within the
framework of GetFEM++? Not that this element is any special --
I could calculate its stiffness matrix explicitly and use generic
assembly routines. However I have problems if figuring out if there
is some sort of support in GetFEM for "structural elements" as I call them.

To be more explicit: one usually  defines the truss element in 
local coordinate system that reduces the problem to 1D. 
Then in case of 2D one uses the transformation matrix:

  T = [ c  s 0 0
        0  0 c s ]   c -- cosine between local and global X axis
                     s -- sine between local and global X axis

 that transforms global degree of freedom Q_i (2 per node) into the 
 local one.
 Of course element stiffness matrix in global coordinate system boils down
 to :
   E*A *   T' * [1,-1;-1,1] * T     where E*A is the bar stiffness.

 The question essentially is -- what is the most "GetFEMic" way of handling
 the matrix T?


 Regards

 Roman
--  
Roman Putanowicz, PhD  < address@hidden  >
Institute for Computational Civil Engng (L-5)
Dept. of Civil Engng, Cracow Univ. of Technology
www.l5.pk.edu.pl, tel. +48 12 628 2569, fax 2034