UCONST.F - - Cubic St.Venant Example
The uconst.f file in the user directory
allows one to create user constitutions that will be added to FEAP's material
library for use with FEAP's internal elements. To set up a user constitution
one needs to edit the file uconst.f to include the code for reading
input data for the new model; this will be stored in the ud(*) array and kept
separate from FEAP's own material data array d(*). The other routine to be edited
is the umodel.f file which will be called when the stresses etc. need to
be computed for residual and tangent operations etc. What is shown below is a
rather elementary implementation that does not get to fancy.
The main steps in creating a user constitution are:
- Edit uconst.f to set the material identifier number umat which corresponds
to the user model type requested in the input file.
- Edit uconst.f so that it reads in the user data and passes it out in ud(*)
and additionally in n1 and n3 set the required history amounts per gauss point.
- Edit umodel.f so that it responds to the following isw switches
isw = 3 Compute stressess and material tangent
isw = 4 Compute stresses for output
isw = 6 Compute stresses for use in residual calculations
isw = 8 Compute stresses for use in plotting
To use the model one needs to compile the following routines. A sample call
to these routines would look something as follows
In this alpha, beta, and gamma are the 3 cubic constants and aaxis and baxis
denote the direction of two of the principal cubic axes in the coordinate frame
used to define the mesh. They need not be unit length but they must be orthogonal.
The program automatically computes the third principal cubic axis internally.
If you wish to run the model in the small deformation setting use:
Source files: Dowloading versions
Description of the consitutive equation