The new TopOpt App from DTU

Ole Sigmund's DTU topology optimization team released their TopOpt App for iOS, Android and Web. This is pretty cool stuff. It allows to play with any variant of a compliance problem. With respect to the original TopOpt web application it is interactive and as such it is as interactive as our our iTop web application (eamc080.eam.uni-erlangen.de/iTop. IMHO, the TopOpt app suits better a tablet than a smartphone/ iPod, but on a tablet it is really interactive, and it is real fun to play with it. I let my 5 years old daughter play with the TopOpt app what would not work with iTop.

With the TopOpt app being an off-line app, I started to show almost any person (I have a beer with and who is not escaping fast enough) what this topology optimization stuff is all about on my iPod.

From the technical point of view I'm impressed by the performance. It is clear, that despite their user experience, the ARM processing power is significant slower than our iTop Xenon CPU. I would have guessed that the performance wouldn't be sufficient and I would have been wrong! I wonder about the direct solver and the Heaviside filter parameters.

So what it the difference to iTop? The TopOpt app is self-explaining while iTop deserves explanation (especially as we still did not write any documentation). But using iTop as a demonstrator tool it allows to explain what is behind

• penalization,
• regularization.
• choice of optimizer,
• the phenomenon of self-penalization,
• start designs/ local optima.

I'm pretty sure the force inverter problem will be soon integrated into the TopOpt app, while interactive material design via inverse homogenization might be a unique feature of iTop for a longer time.

Congratulations, Niels, Morten and Casper! :)

Thesis published

Finished! :)

On the 19th of December 2011 I had the defence of my thesis (Dr. Ing.).



I published my thesis online. You can access it at UB Erlangen-Nuermberg.

The thesis

Topology Optimization of Smart Piezoelectric Transducers

has three main topics:

• topology optimization of a piezoelectric loupspeaker
• topology optimization of a piezoelectric cantilevered energy harvester
• self-penalization in topology optimization

Thank's a lot to my colleagues for the great hat!! :)

I will continue as PostDoc at my current position, working for Prof. Stingl at the chair of applied mathematics from Prof. Leugering.

Interactive Self-Penalization

I added mechanism design to our iTop tool, see also my last post. This allows to play with the force inverter problem. Volume constraint bounds can be switched, regularization can be disabled by setting "reg. value" to one. It makes sense to play with "start optimization from current design". Local solutions are really a problem. Sometimes it helps to play with the physical lower bound (rho^p) and penalization values.

Clearly, the results are not necessarily more "desirable" than the volume constraint results. But IMHO this is not the point. Here not the practical relevance of the result is interesting but the strong self-penalizing effect.

BTW, I finished my PhD! :) More to write about this next week when I officially publish my thesis (online).