Thanks, Wolfgang! It does make sense Regards, Ahmad
On Tue, Oct 5, 2021 at 8:27 PM Wolfgang Bangerth <[email protected]> wrote: > On 9/30/21 9:21 AM, [email protected] wrote: > > > > I would like to solve an elastic problem in a thick slab supported by a > truss > > structure, as shown in the attached image. Looking at this problem, this > is > > how I would discretize the domain > > > > * Use 1D truss elements for the struts shown in green; therefore, one > needs > > to use a Triangulation<1, 3> object > > * Use 3D hex elements for the slab; therefore, we'll be using > > Triangulation<3, 3> > > > > The nodes of 1D and hex meshes may not coincide; therefore, one needs to > > impose appropriate linear constraints. > > > > Thanks to the tutorials, I know how to solve for the strut structure and > the > > slab separately. What I am struggling with is setting up one large > system of > > equations that solves for DOFs in the entire system. > > This isn't entirely trivial. One way is to have DoFHandler objects for > both > the truss structure and the bulk structure. Then you would create a > BlockSparseMatrix and a BlockVector where the (0,0) block of the matrix > and > the (0) block of the vector corresponds to, say, the bulk and the (1,1) > block > of the matrix and the (1) block of the vector corresponds to the > truss(es). > You can build these blocks individually in the same way as you would build > the > corresponding linear system with non-block matrices and vectors for the > individual components. The (0,1) and (1,0) blocks of the matrix are left > empty. > > If you solved the resulting linear system, you would end up with separate > pieces that are not connected. So you need linear constraints that couple > some > of the DoFs of the bulk to the trusses. You can do this via an > AffineConstraints object that is now built not on one or the other of the > DoFHandlers, but indeed on the combination of the two. You'd have to write > some code yourself to figure out what these constraints should be, and how > to > put them into the AffineConstraints object. Applying these constraints to > the > global block linear system then creates the coupling between the two parts. > > Does this make sense? > > Best > W. > > > -- > ------------------------------------------------------------------------ > Wolfgang Bangerth email: [email protected] > www: http://www.math.colostate.edu/~bangerth/ > > -- > The deal.II project is located at http://www.dealii.org/ > For mailing list/forum options, see > https://groups.google.com/d/forum/dealii?hl=en > --- > You received this message because you are subscribed to the Google Groups > "deal.II User Group" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/dealii/cde251a0-3099-fac1-a614-4a4bc927f652%40colostate.edu > . > -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/dealii/CAGCgw4ADShCFCv96d34njHTtx2f5VX2Ukng5zv%3Dh1dSYZ0J0Xw%40mail.gmail.com.
