This directory contains a set of three elastic plane strain example
problems. All problems share the same mesh and material properties,
with the only differences being in the boundary conditions.  The mesh
consists of two quadrilaterals forming a rectangular mesh.

The information describing the examples may be divided into four
groups:

  * Global mesh information: see twoquad4.mesh
  * Parameter settings common to all three examples: see pylithapp.cfg.
  * Material properties common to all three examples: see matprops.spatialdb
  * Example-specific parameters and boundary condition specifications.

The examples and associated files are:

  * axialdisp

    Axial displacements are applied to the left and right edges of the
    mesh.

    - axialdisp.cfg:  Parameter settings.
    - axialdisp.spatialdb: Database of Dirichlet BC values.

  * sheardisp: 

    The left and right edges of the mesh are pinned in the
    x-direction.  The left edge has a negative y-displacement, while
    the right edge has a positive y-displacement.

    - sheardisp.cfg: Parameter settings.
    - sheardisp.spatialdb:  Database of Dirichlet BC values.

  * dislocation

    Fault displacements are applied between the two elements, while
    the left and right edges are fixed in x and y.

    - dislocation.cfg:  Parameter settings.
    - dislocation_slip.spatialdb:  Database of fault slip values.
    - dislocation_sliptime.spatialdb: Database of slip initiation time values.

  * axialtract

    A constant normal traction is applied to the right edge of the mesh.
    The left edge is pinned in the x-direction, and the bottom edge is
    pinned in the y-direction. We include a fault with zero slip to 
    illustrate how the computation of the change in tractions on the
    fault surface.

    - axialtract.cfg:  Parameter settings.
    - axialtract.spatialdb: Database of Neumann BC values.
    - dislocation_slip_zero.spatialdb:  Database of fault slip values.
    - dislocation_sliptime.spatialdb: Database of slip initiation time values.

All of the files are documented.  The 'pylithapp.cfg' file is read
automatically when running PyLith.  To add to or override these
settings, you may place an additional .cfg file on the command line.

To run the examples, you can type:

  pylith axialdisp.cfg
  pylith axialtract.cfg
  pylith sheardisp.cfg
  pylith dislocation.cfg

Each of these commands will produce a corresponding suite of VTK
files, which may be viewed with visualization packages such as
ParaView or Mayavi.  The jpeg files in this directory show results for
the different examples visualized using ParaView.
