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ToPy is a lightweight topology optimization framework for Python that can solve compliance (stiffness), mechanism synthesis and heat conduction problems in 2D and 3D. Please refer to the ToPy Wiki for further information.

ToPy was originally hosted on Google Code.


Once you've downloaded the depenencies (see the INSTALL file) all you need to do is the following:

$ git clone
$ cd topy/topy
$ python install

Alternatively, you can download the latest stable release, but it usually lags a little behind the Master branch (as can be expected).

Getting started

The main class of ToPy is 'Topology'. It defines the main constraints, grid and parameters of optimization -- but you don't really have to bother yourself with this if you just want to get some results.

There are two ways of defining a problem

  1. TPD file: You define the problem with keywords (see Help) in a simple text file and solve via the command line. The text file must have the extension .tpd
  2. Config dictionary: This is similar to the TPD file approach, however, you define the problem directly in a Python file; it's very useful if you want to experiment and don't want to keep making changes to a text file. You can later save the Config keywords to a TPD file.

TPD (ToPy Problem Definition) file

There is a minimal set of parameters which is required for successful definition of a ToPy problem:

PROB_TYPE  : comp
PROB_NAME  : mbb_beam_minimal
ETA        : 0.5
DOF_PN     : 2
VOL_FRAC   : 0.5
FILT_RAD   : 1.5
P_FAC      : 3
ELEM_K     : Q4
NUM_ITER   : 10

You can read more about successful problem definition here.

When the TPD file is defined, then the rest is simple:

from topy import Topology

topology = Topology()

Config dictionary

First you have to define a config dictionary (note the similarity with a TPD file, especially the keywords):

config = {
     'DOF_PN': 2,
     'ELEM_K': 'Q4',
     'ETA': '0.5',
     'FILT_RAD': 1.5,
     'FXTR_NODE_X': range(1, 22),
     'FXTR_NODE_Y': 1281,
     'LOAD_NODE_Y': 1,
     'LOAD_VALU_Y': -1,
     'NUM_ELEM_X': 60,
     'NUM_ELEM_Y': 20,
     'NUM_ELEM_Z': 0,
     'NUM_ITER': 94,
     'PROB_NAME': 'beam_2d_reci',
     'PROB_TYPE': 'comp',
     'P_FAC': 3.0,
     'VOL_FRAC': 0.5

The requirements are the same as for the TPD file.

topology = Topology(config=config)

Optimization (solving the problem)

You can use the command line solution:

$ python topy/scripts/ <filename>.tpd

Or you can use a Python script:

import topy

config = {...}
t = topy.Topology(config)

Visualization (seeing the result)

Module topy.visualization allows one to save the output as a .png image for 2D problems or as a .vtk file for 3D. The VTK files can be viewed with Mayavi or ParaView. You can animate the PNG images with the convert tool.

convert -delay 35 *.png anim.gif



Solved examples


How to cite ToPy

If you've used ToPy in your research work, please consider to cite:

  author = {Hunter, William and others},
  title = {ToPy - Topology optimization with Python},
  year = {2017},
  publisher = {GitHub},
  journal = {GitHub repository},
  howpublished = {\url{}},