[CIG-SHORT] How to obtain initial stresses on the node of the hex geometry

[Farhan Javed]

Hi,

I am trying to output the initial stresses on the hex nodes for the 3D
geometry of the region using density contrast.There is a available python
script i.e. generate_statedb.py for 2D gravity problem. If I output the
average initial stresses on the cell center, and re-run the simulation, It
should give me zero deformation, but It gives very high displacement
values. I need these initial stresses due to density contrast to constrain
the equilibrium or near equilibrium conditions at the beginning of a
simulation. Please can you guide me how to write a matrix for hex geometry
as It was provided for quad4 cell in the generate_statedb.py python script.
I am copying the part of the basis function for quad4 cell provided in the
script:

# Basis functions for quad4 cell evaluated at quadrature points. Use
# to compute coordinate of quadrature points in each cell from
# coordinates of vertices. Note the order must correspond to the order
# of the data at the quadrature points in the output.

qpts = numpy.array([[ 0.62200847,  0.16666667,  0.0446582,   0.16666667],
                    [ 0.16666667,  0.62200847,  0.16666667,  0.0446582 ],
                    [ 0.16666667,  0.0446582,   0.16666667,  0.62200847],
                    [ 0.0446582,   0.16666667,  0.62200847,  0.16666667]],
dtype=numpy.float64)







Thanks you in advance.


Farhan Javed
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