batubay/pycalculix

Python 3 library to automate and build finite element analysis (FEA) models in Calculix. Meshing uses Calculix or GMSH.

pycalculix

pycalculix is a Python 3 library to automate and build finite element analysis (FEA) models in Calculix.

Website: http://justinablack.com/pycalculix/
Source Code: https://github.com/spacether/pycalculix
Documentation: https://pycalculix.readthedocs.io/en/latest/index.html

Useful applications of Pycalculix

• Trade studies for plane stress, plane strain, or axisymmetric parts
• Quick Kt analysis of 2D geometry
• Learning finite element analysis (FEA) and Python

Installation

Mac OS X

1. Install python3, pycalculix and the fea programs that it uses

brew install python3
python3 -mpip install -U numpy
python3 -mpip install -U matplotlib
pip3 install pycalculix
pycalculix-add-feaprograms

2. You are done! See 'Usage'

Windows

1. Install python3 for 32bit machines or 64 bit machines
2. In a terminal run the below lines to install needed python libraries, pycalculix, and the fea programs that it uses

python -mpip install -U numpy
python -mpip install -U matplotlib
pip install pycalculix
pycalculix-add-feaprograms

3. You are done! See 'Usage'

Linux, assumes Ubuntu 16.04

1. Install python3-pip, numpy, matplotlib, pycalculix, and the fea programs that it uses

sudo apt-get install python3-pip python3-tk
pip3 install --upgrade pip
python3 -mpip install -U numpy
sudo python3 -mpip install -U matplotlib
pip3 install pycalculix
pycalculix-add-feaprograms

2. You are done! See 'Sample Program' and 'Usage'

Sample Program

# this is from examples/hole-in-plate-full.py
import pycalculix as pyc

# Vertical hole in plate model, make model
proj_name = 'hole-in-plate-full'
model = pyc.FeaModel(proj_name)
model.set_units('m') # this sets dist units to meters

# Define variables we'll use to draw part geometry
diam = 2.0 # hole diam
ratio = 0.45
width = diam/ratio   #plate width
print('D=%f, H=%f, D/H=%f' % (diam, width, diam/width))
length = 2*width  #plate length

# Draw part geometry, you must draw the part CLOCKWISE, x, y = radial, axial
part = pyc.Part(model)
part.goto(length*0.5, -width*0.5)
part.draw_line_ax(width)
part.draw_line_rad(-length)
part.draw_line_ax(-width)
part.draw_line_rad(length)
hole_lines = part.draw_hole(0, 0, diam*0.5, filled=False)
model.set_ediv(hole_lines, 10)
part.chunk()
model.plot_geometry(proj_name+'_geom') # view the geometry

# set loads and constraints
pressure = -1000
model.set_load('press', part.top, pressure)
model.set_load('press', part.bottom, pressure)
model.set_constr('fix', ['P6', 'P8'], 'y')
model.set_constr('fix', ['P4', 'P7'], 'x')

# set part material
mat = pyc.Material('steel')
mat.set_mech_props(7800, 210*(10**9), 0.3)
model.set_matl(mat, part)

# set the element type and mesh database
model.set_eshape('quad', 2)
model.set_etype('plstress', part, 0.1)
model.mesh(1.0, 'gmsh') # mesh 1.0 fineness, smaller is finer
model.plot_elements(proj_name+'_elem')   # plot part elements
model.plot_pressures(proj_name+'_press')
model.plot_constraints(proj_name+'_constr')

# make and solve the model
prob = pyc.Problem(model, 'struct')
prob.solve()

# view and query results
sx = prob.rfile.get_nmax('Sx')
print('Sx_max: %f' % sx)

# Plot results
fields = 'Sx,Sy,S1,S2,S3,Seqv,ux,uy,utot,ex'    # store the fields to plot
fields = fields.split(',')
for field in fields:
    fname = proj_name+'_'+field
    prob.rfile.nplot(field, fname, display=False)

Usage

1. To run a pycalcuix file you have to have pycalulix installed, see 'Installation' above
2. The you can then write your own pycalculix programs or run one of the example files here: https://github.com/spacether/pycalculix/tree/master/examples
3. To run a file:

Windows

• Graphical user interface:
  • Double click the file
    If the .py extension is associated correctly you can double click it to run the .py program
• Console:
  • cd into the directory with your .py file in it, then in the terminal enter

  python the_program.py
  

  where the_program.py is the name of the file that you are running This assumes that python3 is your active python installation

Mac/Linux

• Console:
  • cd into the directory with your .py file in it, then in the terminal enter

  python3 the_program.py
  

  where the_program.py is the name of the file that you are running

Elements Supported:

Axisymmetric, plane stress, and plane strain elements are supported.

• First and second order triangles and quadrilaterals are supported.
  • First order elements only have corner nodes
  • Second order elements have corner and midside nodes

Second order elements produce more accurate results Setting element divisions on lines is supported

Geometry Building

• One can build separate parts made of points, lines, arcs, and areas.
• Straight lines and arcs are currently supported.
• One can draw a part made of straight lines, then smooth out corners by adding arcs with the part method: part.fillet_lines(L1, L2, arc_radius)
• The new arc will be tangent to both adjacent lines.

Loading

• Force loading
• Constant pressure
• Linearly varying pressure (water pressure)
• Gravity
• Rotational speed forces
• Displacement constraints
• Loads are stored on geometry primitives (points lines, areas) and can be applied before or after meshing.

Files Produced

Meshing and solving are done in the background using cgx or gmsh for meshing, and Calculix ccx for solving.

Files Used:

• .fbd (Calculix cgx geometry file)
• .inp (Calculix solver input file, or mesh definition)
• .geo (Gmsh geometry file)
• .msh (Gmsh native mesh file)
• .frd (Calculix ccx nodal results file, values are at nodes and were created by interpolating element integration point results back to the nodes)
• .dat (Calculix ccx element results file, includes integration point results)

Uninstall

Windows

pycalculix-remove-feaprograms
pip uninstall pycalculix

Mac/Linux

pycalculix-remove-feaprograms
pip3 uninstall pycalculix

Development

• Download this repo

git clone [email protected]:spacether/pycalculix.git

• Make python3 virtual env

python -m venv venv

• Activate it
  • Windows venv\scripts\activate
  • Mac/linux source venv/bin/activate
• Locally install pycalculix

pip install -e .
pycalculix-add-feaprograms

• Now any changes that you make to your local version of pycalculix will be live in your virtual environment

License

See LICENSE.txt (Apache 2.0)

Creator

Justin Black, justin.a.black[at-sign]gmail[dot]com Initial Release: December 2014

Changes

See the change log