[CIG-SHORT] Combine loading boundary conditions and absorbing boundary condition

[Li, Teng]

Hi,
I have a 2d rectangular model and in this model, all the four faces are absorbing boundary conditions. Now in order to add initial normal stress and shear stress for the whole domian, I use Neumann boundary conditions. Here, I paste only one part for your convenience:

# ----------------------------------------------------------------------
# boundary conditions
# ----------------------------------------------------------------------
[pylithapp.timedependent.bc]
# Change the default Dirichlet BC to the AbsorbingDampers BC
x_pos = pylith.bc.AbsorbingDampers
x_neg = pylith.bc.AbsorbingDampers
y_neg = pylith.bc.AbsorbingDampers
y_pos = pylith.bc.AbsorbingDampers


#-----------------------------------------------------------------------
# x positive
# ----------------------------------------------------------------------
[pylithapp.timedependent.bc.x_pos]
# Absorbing BC on +x face of bar

# Name of nodeset in CUBIT
label = face_xpos

# Specify a UniformDB for the initial tractions
db_initial = spatialdata.spatialdb.UniformDB
db_initial.label = Neumann BC on +x
db_initial.values = [traction-shear-vert, traction-normal]
db_initial.data = [20.0*MPa, -50.0*MPa]

# Specify label and filename for spatial database with physical properties
db.label = Absorbing BC +x
db.iohandler.filename = matprops.spatialdb

# Specify the basis functions and quadrature:
# 1-D Lagrange cell in 2-D space with 2nd order quadrature
quadrature.cell = pylith.feassemble.FIATLagrange
quadrature.cell.dimension = 1
quadrature.cell.quad_order = 2


However, I see the manual, that we should change BC type to Neumann:

bc.x_pos = pylith.bc.Neumann,

So I am wondering how can I apply the initial stress that keep the whole domain in the initial stress condition while keep the absorbing boundary conditions of all the faces.

Best wishes
Teng Li


Teng Li

Master Candidate in Structures

Department of Civil and Environmental Engineering

University of Illinois at Urbana-Champaign

205 North Mathews Ave, Urbana, IL. 61801

Phone:(217)8196210, Email: tengli2 at illinois.edu


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