WCSMO-8 is over

WCSMO-8 ist almost over. For me it was my first congress and I was looking forward to finally "become part of the community". It turned out, that DCAMM 07 was actually a real good introduction to it as I know already Martin Bendsoe, Ole Sigmund, Jakob Jensen and several of their PhD students. I got some answers and ideas from them - that will bring me a good step forward.

A very big surprise was actually to meet Cory Rupp, of whom I never heard of. He did his PhD on the topology optmization of a piezoelectric plate energy harvester. It turned out, that our work has very much in common - escpcially our observations in the dynamic case and the self-penalization effect of piezoelectric-mechanical laminates (I take the term "self-penalization" from Ole Sigmund, who made this observation in another context before). It gave me a real push to find someone who shares my experiences. His paper is "Topology Optimization of Piezoelectric Energy Harvesting Structures And Circuits" (#1594) by Cory Rupp, Martin Dunn and Kurt Maute.

I found that also Maria Duehring is doing now cool piezoelectric stuff. I liked her older paper about acoustic optimization and used it for a paper seminar. Before that conference I knew only of Emilio Silva and Alberto Donoso/ Jose Bellido doing piezoelectric topology optimization.

The highligts of the conference? Both Martin Bendsoe and Ole Sigmund pointed out a paper where the topology optimization of the head equation is used to find the best path for a robot within a room of obstacles - actually really cool and innovative. That's cross-thinking! It's entitled "Novel Mobile Robot Path Planning Algorithm by Equivalent Conduction Heat Flow Topology Optimization" (#1327) by Jae Chun Ryu, Yoon Young Kim and Chongwoo Park from South-Korea.

I liked most the talk of Ole Sigmund, where he presented an "engineering solution" (simple, robust, effective) to generate more robust designs. The idea is to perfom the
optimization also on a thickened (dilation) and thinned (erosion) variant and perfom a min max optimization. He pointed out, that the level-set method has a big natural advance here, as you get arbitrary variants of your design easily - simply by shifting the level-set. The paper is "Manufacturing Tolerant Topolog Optimization" (# 1535)

The most touching moment was, when an aircraft designer asked us in his talk to stand up in silence in memory to the people who died at the Air France Airbus crash this week.

Structural vs. Acustic Piezoelctric Loupspeaker Optimization

Here comes my own talk from WCSMO-8. It deals with the topology optimization of a piezoelectric loudspeaker. I consider the full coupling with acoustics and a pure structural approximation. Both cases are compared and it turns out, that for my model, the structural approximation does not hold for most cases as the objective function favours vibrational patterns that actually lead to acoustic short circuits. What I do is actually to load the final topologies from the structural optimization and evaluate the sound power with a fully coupled simulation.

This might also be the first publication about a fully piezoelectric-mechanical-acoustic coupled loudspeaker. The interesting thing is that the structural eigenmodes both cannot be excited by a full piezoelectric patch and also would result in acoustic short circuits.

For a weakly coupled form, using boundary elements, Nils Olhoff and Jianbin Du presented "Minimization of Sound Pressure in the Acoustic Field Generated by Vibrating Structures Using Topology Optimization" (#1396).

You can have a look to my talk (download talk)

Topology Optimization of a Piezoelectric Loudspeaker Coupled with the Acoustic Domain

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and download the conference proceedings paper. The title is "Topology Optimization of a Piezoelectric Loudspeaker Coupled with the Acoustic Domain" (#1230) by Fabian Wein, Manfred Kaltenbacher, Fabian Schury, Eberhard Baensch and Guenter Leugering.