Hello Peter,
Within was only recently acquired by autodesk, the software itself exists for some years now. I work in the addtitive manufacturing area (R&D) and was interested in buying because of the mentioned FEM aided topology optimisation. The reason there is no demo is simple, it's one of the most expensive software packages I know. The price is around 50 k€ per year! There is no option for a perpetual license.
The other big competitors to within are: Simpleware ScanIP (http://www.simpleware.com/software/cad-module/) with the module +CAD, netfabbs selective space structures (http://www.netfabb.com/structure.php) and materialise 3-matic (http://software.materialise.com/3-matic-lightweight-structures-module). All of these cost around 20 - 30 k€, but as far as i know dont have an integrated FEM aided topology optimisation.
I now use Simpleware ScanIP with +CAD and am very happy so far. There was the option for perpetual license, which was important for me.
What you have to consider is the following:
All these programs are mainly in use for generating lattice structures for any kind of powder based (SLM, SLS, EBM...) or resin based (stereolithography, polyjet...) printers or combinations of the two (powder base plus binder ala voxeljet). Due to the intricate lattice structures, I see no practical use for FDM parts. Just print one of them voronoi vases and try and break them, it's quite easy.
In my opinion the best way to realize what you want to do is to focus solely on topology optimisation and generate the lattices only internally like you do in any other printjob with infill below 100%. The internal infill generated by the usual FDM slicers generally has good mechanical stability due to the fact, that the infill patterns are (in most infills structures like rectilinear) generated in continous lines. Thus, you get a good welding to the polymer below. Opposed to that, if you have your lattice (e.g. voronoi) already in the stl file, the paths generated by the slicer will not be continuous. Thus many lifts/retracts, hard work on the motors which can lead to vibrations and so you end up with comparably bad welds between the lattice features.
I found a list with software for topology optimisation, but do not know if any of them has a demo or is free: [
www.topology-opt.com]
If you have further questions, just ask.
Best regards,
krosstoph