Fatlab 2.034 available. Now with anisotropy feature

A new version has just been released along with an associated example. This time, the main feature is the handling of anisotropic fatigue strength, as is needed in several cases, e.g. for additive manufacturing.

A relatively simple approach is taken, where the fatigue strength is scaled according to the surface angle of a given node relative to a user-defined reference direction, e.g. the direction of gravity during a print.

Video Tutorial

After many requests, I have now created a video tutorial showing how to get started using Fatlab. The video shows how to export the model and stress files from ANSYS and setup the analysis in Fatlab.

The video is on youtube. Use the high resolution to see what is going on. Hopefully more will follow and hopefully they will be better and without the annoying watermark.

Fatlab getting started tutorial.

Site updated

FatigueToolbox just got a major overhaul. In addition to the Fatlab project, it now contains several other fatigue resources such as publications and fatigue data. In the future, the site will be updated more regularly and with more broad fatigue topics.

Nice CT scans of 3D aluminum printed fatigue test specimens.

Minor updates

Fatlab and the examples have been updated to accommodate for changes in Matlab 2018b and ANSYS 18.2.

In Matlab, the figure window has been changed due to the new zoom features (using the mouse wheel).

In ANSYS, the default format of text based stress output has been changed to include one more zero in the exponent.

Parallel execution option available

As mentioned, the standalone version will be discontinued and only the source will be provided for running under Matlab. This is because the deployed version behaved slightly different than the source version, and ran much slower. So, going forward, development will not be halted by limitations of the deploytool.

One of the limiting issues of the deployed version was in parallel execution of the code. It ran fine in Matlab, but not when deployed. So now this feature has been re-implemented, as of Fatlab 2.022. It uses the Parallel Computing Toolbox. Fatlab will detect whether the toolbox is installed and enable it accordingly. The user can then select a number of cores for the execution under Run Analysis.

Special thanks to Martin Dahl Kilt for helping with this feature and performance issues.

Support for shell elements

As of version 2.008 Fatlab will support also support the following ANSYS shell elements; SHELL63,  SHELL181 and SHELL281. Additionally, the wireframe display now works for both plane and shell elements as well as solid elements of course.



Fatlab 2.006 available

Fatlab 2.006 is now available (source only, the standalone version will not be updated for the time being). The source code has been moved to SourceForge and is now under SVN version control, thus the change in version numbering. The commit log is now public.

The new version includes support for 2D ANSYS elements; PLANE42, PLANE82, PLANE182 and PLANE183. Like all other elements, only the corner nodes are read, so the will be limited difference between the Q4 and Q8 elements in Fatlab.



  • In some cases, the extraction of peaks/valleys from the stress signal were faulty. The extraction routine could not detect a peak consisting of two identical values, but it can now. The problem would occur e.g. for a sine load with an unfortunate number of sample points
  • For very long lives Fatlab would report infinite utilization under some circumstances. This was due to the use of single precision format in some of the calculations, which maxes out at approximately 10^38. Now using double precision, this is no longer an issue.
  • There were some problems using Matlab 2016a & b (graphics only) which have now been fixed, so Fatlab will run equally well in any Matlab version from 2015aSP1 and forward.

New example added

A new example have been added, which shows how to setup a model with a bolted joint including pretension. The model is also subjected to “bi-linear loading” due to two hinged actuators which are either pulling or pushing, leading to very different stress responses depending on the loading direction.


Improved user interface

The newest version of Fatlab (1.41) contains a number of improvement in the user interface:

  • Individual parts of the FE model can now be turned on/off, both visually and in the calculations. Parts are now also highlighted when selected.
  • Most view modifying control elements have been moved to the toolbar
  • Toggling eg. coordinate system etc. on/off does now not reset the current plot
  • Element borders can now be hidden/shown
  • 3D connexion pointing devices are now supported
  • Many bugfixes and speed improvements, e.g. on loading