pyansys 0.28.0

Pythonic interface to ANSYS binary files

This Python module allows you to:

• Interactively control an instance of ANSYS using Python. Linux only (for now).

• Extract data from ANSYS files and to display them if VTK is installed.

• Read in result (.rst), mass and stiffness (.full), and block archive (.cdb) files.

See the Documentation page for more details.

Installation

Installation through pip:

pip install pyansys

You can also visit GitHub to download the source.

Dependencies: numpy, cython, vtkInterface. Optional: vtk

Minimum requirements are numpy to extract results from a results file. To convert the raw data to a VTK unstructured grid, VTK 5.0 or greater must be installed with Python bindings.

Quick Examples

Many of the following examples are built in and can be run from the build-in examples module. For a quick demo, run:

from pyansys import examples
examples.RunAll()

Controlling ANSYS

Create an instance of ANSYS and send commands to it.

import os
import pyansys

path = os.getcwd()
ansys = pyansys.ANSYS(run_location=path)

# create a square area using keypoints
ansys.Prep7()
ansys.K(1, 0, 0, 0)
ansys.K(2, 1, 0, 0)
ansys.K(3, 1, 1, 0)
ansys.K(4, 0, 1, 0)
ansys.L(1, 2)
ansys.L(2, 3)
ansys.L(3, 4)
ansys.L(4, 1)
ansys.Al(1, 2, 3, 4)
ansys.Save()
ansys.Exit()

Loading and Plotting an ANSYS Archive File

ANSYS archive files containing solid elements (both legacy and current), can be loaded using ReadArchive and then converted to a vtk object.

import pyansys
from pyansys import examples

# Sample *.cdb
filename = examples.hexarchivefile

# Read ansys archive file
archive = pyansys.ReadArchive(filename)

# Print raw data from cdb
for key in archive.raw:
   print("%s : %s" % (key, archive.raw[key]))

# Create a vtk unstructured grid from the raw data and plot it
grid = archive.ParseVTK()
grid.Plot()

# write this as a vtk xml file
grid.Write('hex.vtu')

You can then load this vtk file using vtkInterface or another program that uses VTK.

# Load this from vtk
import vtkInterface
grid = vtkInterface.UnstructuredGrid('hex.vtu')
grid.Plot()

Loading and Plotting an ANSYS Result File

This example reads in binary results from a modal analysis of a beam from ANSYS. This section of code does not rely on vtk and can be used solely with numpy installed.

# Load the reader from pyansys
import pyansys

# Sample result file
from pyansys import examples
rstfile = examples.rstfile

# Create result reader object by loading the result file
result = pyansys.ResultReader(rstfile)

# Get the solution time values (natural frequencies for this modal analysis)
freqs = result.GetTimeValues()

# Get the node numbers in this result file
nnum = result.nnum

# Get the 1st bending mode shape.  Nodes are ordered according to nnum.
disp = result.GetNodalResult(0, True) # uses 0 based indexing

# it's just a numpy array
print(disp)

[[  0.           0.           0.        ]
 [  0.           0.           0.        ]
 [  0.           0.           0.        ]
 ...,
 [ 21.75315943 -14.01733637  -2.34010126]
 [ 26.60384371 -17.14955041  -2.40527841]
 [ 31.50985156 -20.31588852  -2.4327859 ]]

You can plot results as well directly from the file as well.

# Plot the displacement of the 1st in the x direction
result.PlotNodalResult(0, 'x', label='Displacement')

# Plot the nodal stress in the 'x' direction for the 6th result
result.PlotNodalStress(5, 'Sx')

Reading a Full File

This example reads in the mass and stiffness matrices associated with the above example.

# Load the reader from pyansys
import pyansys
from scipy import sparse

# load the full file
fobj = pyansys.FullReader('file.full')
dofref, k, m = fobj.LoadKM()  # returns upper triangle only

# make k, m full, symmetric matricies
k += sparse.triu(k, 1).T
m += sparse.triu(m, 1).T

If you have scipy installed, you can solve the eigensystem for its natural frequencies and mode shapes.

from scipy.sparse import linalg

# condition the k matrix
# to avoid getting the "Factor is exactly singular" error
k += sparse.diags(np.random.random(k.shape[0])/1E20, shape=k.shape)

# Solve
w, v = linalg.eigsh(k, k=20, M=m, sigma=10000)
# System natural frequencies
f = (np.real(w))**0.5/(2*np.pi)

print('First four natural frequencies')
for i in range(4):
    print '{:.3f} Hz'.format(f[i])

First four natural frequencies
1283.200 Hz
1283.200 Hz
5781.975 Hz
6919.399 Hz

License and Acknowledgments

pyansys is licensed under the MIT license.

ANSYS documentation and functions build from html provided by Sharcnet. Thanks!

This module, pyansys makes no commercial claim over ANSYS whatsoever. This tool extends the functionality of ANSYS by adding a python interface in both file interface as well as interactive scripting without changing the core behavior or license of the original software. The use of the interactive APDL control of pyansys requires a legally licensed local copy of ANSYS.