FAME blog: Sneak peek into the Topology Optimization software world

Author: Kenneth Edsvik, Head, Products, Citec Oy Ab

Technical content by Toni Mahla, Senior Design Engineer, Citec Oy Ab

Sneak peek into the Topology Optimization software world

Christmas is coming and even though gifts related to knitting seem to be popular, some of us technology enthusiasts might think which Topology optimization software to put on Santa’s list.

We at Citec decided to scratch the surface a bit deeper and find out which Topology Optimization software would be optimal for different needs. In our research within DREAMS project, we put Altair Inspire, nTopology, Siemens NX TO module and Nastran SOL 200 under the looking glass.

Before going into the details there are some basics to understand. First of all you need to set your goals, which can be price or weight reduction, improving the function or perhaps related to esthetical reasons. The software is smart but still your effort is needed to tell it which are the objectives and boundaries it needs to meet. Objectives can typically be to maximize the stiffness or to minimize the volume. Removal of material, forces and for example structural restrictions are your boundaries.

TO workflow consists of different stages such as pre- and post-processing, that however should not be mixed with the actual manufacturing process steps.

When looking at the pre-processing step you can find both pros and cons between the different providers. For example with nTop and SOL200 you can utilize the vector point field import from a simulation software to define e.g. force, pressure, deformation and temperature.
Some providers relay on traditional B-rep modelling while other offer implicit modelling, that is found out to be more reliable in complex geometries. There are also considerable differences in controlling the mesh and converting it to solid, just to mention some findings.
While setting the objectives and boundaries for solving the significant difference was the lack of support for sliding contact, which was crucial for the test item in our case. In our research the only provider for this feature is currently Inspire. However, with nTop and SOL200 the user can import contact forces from FEA software where sliding contact is supported to get realistic load as sliding contact is not supported, while NX TO came out with unaccepted results due to lack these features.
Before you go further you still might want to post-process your model for the actual printing. Here Inspire picks the longest straw, just ahead of nTop, which do have advanced controls for smoothening, but lacks in converting primitive shapes to solid geometry. Smooth quality is also achieved with NX TO but it? cannot convert the optimized geometry to solid body. SOL200 was unable to smoothen the surface even though you squeeze the element size to minimum.
From user interface and usability point of view there are factors like work steps, model re-usability, support documentation, calculation time and software stability to think about.

Based on our research all software has their pros and cons, highly depending on your needs. The testing continues with good pace and as this research is part of DREAMS project, funded by Business Finland, we are now a bit wiser and hopefully ready to send out our wish list just before Christmas. Stay tuned!