FEDEASLab for Finite Element Analysis in CE 222
FEDEASLab (password protected)
is a Matlab program for matrix structural analysis developed by
Professor F.C. Filippou.
This is the linear analysis version of FEDEASLab; it does not include the
functions for nonlinear analysis.
We will extend FEDEASLab for finite element analysis in
CE 222.
FEDEASLab requires
Matlab Version 7.x or higher.
The
CEE Computer Labs
has the current versions of Matlab.
The m-files for using FEDEASLab for finite element analysis are listed
in two categories:
(i) original FEDEASLab functions and (ii) modified functions needed for
finite element analysis.
Updates on functions--March 4, 2005
Please use these updated functions:
tie.m
ElmQD4.m
Original FEDEASLab Functions
The zip-file contains the
Basic FEDEASLab distribution (37k)
Modified FEDEASLab Functions
FEDEASLab was designed for structural analysis problems with
a small number of DOF, hence it stores the global stiffness matrix, Kf,
as a full ndf x ndf matrix.
For finite element analysis, the number of DOF is much larger, and so
it is necessary to store Kf in a sparse matrix form.
Matlab has excellent functions for manipulating and solving sparse
systems of equations.
The following zip-file contains
FEAnalysis extensions. This
includes the functions for creating an FE model, forming and
solving the equilibrium equations, and the functions
for 2-D finite element analysis.
See the Examples directory in FEAnalysis for several examples using
triangular and quadrilateral elements. These are described below.
Examples
Constant Strain Triangle
The following m-files illustrate the CST element and the block/tie functions
to create meshes.
- beam.m, Cantilever beam (one block)
- curved.m, Curved beam (multiple blocks)
- patchCST.m, Patch test for CST element
Another interesting example is semicircle.m,
which uses CST elements to analyze a semi-circular disk in plane stress.
Instead of using the block function, the mesh is generated
using Delaunay triangularization, for which Matlab has a function.
First, the nodal points coordinates are generated by mapping from polar
coordinates.
The example delaunayMesh.m
generates the FEDEASLab data structures after calling the delaunay.m
function to generate the triangular element connectivity.
Then the Delaunay function is called to generate the
element connectivity for the triangular elements.
The procedure produces an optimal mesh in the sense that the elements
have the best shape for the generated nodal point coordinates.
The deformed mesh for the semi-circular problem is:
Quadrilateral Element
The cantilever beam problem can be analyzed with the 4-node, quadrilateral
element ElmQD4.
The patch test for the element is in patchQD4.m.
Return to CE 222
Structural Engineering, Mechanics and Materials
Department of Civil and Environmental Engineering
University of California, Berkeley
fenves@berkeley.edu