Nothing special for most of the people I cite, but the first time for me:
My (our) first paper exists in "real world" with the current issue of
IJAEM "International Journal of Applied Electromagnetics and Mechanics".
Topology optimization of a piezoelectric-mechanical actuator with single- and multiple-frequency excitation
It's part of a OIPE 2008
special issue with 17 selected papers out of 68 full paper submissions.
Contact me if you have no access to the journal :)
I'm 2/3 finished with another paper: "Self-Penalizing Topology Optimization of Piezoelectric Composite" - I hope it works out. It is kind of a "baby-review" paper
where the cited algorithms are implemented for the same model.
Wednesday 23 September 2009
Monday 27 July 2009
About my new job
I have been financend for three years by the DFG (the main German research fond) within the priority program SPP 1253 which is about the optimization of partial differential equations. This support and the possibility to work on the research project Optimization of Electro-Mechanical Smart Structures is grateful acknowledged. As a fourth year to finish my Ph.D. was planned, we applied for a second funding period which was unfortunately refused - it turned out, that actually all engineers were cut off this mathematical program.
Fortunately I got an offer by Prof. Michael Stingl for a full time position. I now work within the Excellence Cluster Engineering of Adcanced Materials. My tasks are closely related to what I am already doing (including the software basis CFS++) and after concurrently finishing my PhD I will continue as a postdoc. Formally I am now employed by the Chair of Applied Mathematics II of Prof. Leugering who was also one of the project leaders of the funded project.
Nevertheless, my PhD advisors have not changed. This is Prof. Manfred Kaltenbacher now in Klagenfurt/ Austria (check the first link - this is a real Austrian title concatenation :) ) and Prof. Eberhard Bänsch, head of the Chair for Applied Mathematics III. So in some sense I am also still a member of this chair.
Furthermore I did no loose my ties to the Chair of Sensor Technology as Prof. Lerch offered me to keep my desk there and I want to be there once a week.
So I am rather split/ networked/ ... and somehow more "mathematically oriented" - but note that I am still an engineer (having even two of such degrees) :)
Fortunately I got an offer by Prof. Michael Stingl for a full time position. I now work within the Excellence Cluster Engineering of Adcanced Materials. My tasks are closely related to what I am already doing (including the software basis CFS++) and after concurrently finishing my PhD I will continue as a postdoc. Formally I am now employed by the Chair of Applied Mathematics II of Prof. Leugering who was also one of the project leaders of the funded project.
Nevertheless, my PhD advisors have not changed. This is Prof. Manfred Kaltenbacher now in Klagenfurt/ Austria (check the first link - this is a real Austrian title concatenation :) ) and Prof. Eberhard Bänsch, head of the Chair for Applied Mathematics III. So in some sense I am also still a member of this chair.
Furthermore I did no loose my ties to the Chair of Sensor Technology as Prof. Lerch offered me to keep my desk there and I want to be there once a week.
So I am rather split/ networked/ ... and somehow more "mathematically oriented" - but note that I am still an engineer (having even two of such degrees) :)
Friday 5 June 2009
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.
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)
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.
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
View more Microsoft Word documents from fwein.
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.
Saturday 23 May 2009
CU@WCSMO-8 in Lissbon
Hi topology optimizers outside,
thanks to FEEDJIT I know that indeed some guys are reading my blog. In case you are topology optimizers and
also participate at the WCSMO ("World congress" sounds nice :)), you can meet me at my session 19.1, wednesday (I'm the last 9:30-9:50). 19 is about "Multiphysics Topology Optimization".
I talk about a comparisson of topopolgy optimization within the acoustic domain and the pure structural approximation. Clearly via piezoelectric excitation and as common for me, I have no penalization, no volume constraint and achieve quite good 0-1 results w/o any regularization. I also speak about the vibrational patterns: the mechanical eigenmodes, the piezoelectric excitation of these and the link to acoustic short circuits.
It would be actually nice to finally learn to know a reader of my blog. :)
thanks to FEEDJIT I know that indeed some guys are reading my blog. In case you are topology optimizers and
also participate at the WCSMO ("World congress" sounds nice :)), you can meet me at my session 19.1, wednesday (I'm the last 9:30-9:50). 19 is about "Multiphysics Topology Optimization".
I talk about a comparisson of topopolgy optimization within the acoustic domain and the pure structural approximation. Clearly via piezoelectric excitation and as common for me, I have no penalization, no volume constraint and achieve quite good 0-1 results w/o any regularization. I also speak about the vibrational patterns: the mechanical eigenmodes, the piezoelectric excitation of these and the link to acoustic short circuits.
It would be actually nice to finally learn to know a reader of my blog. :)
Friday 20 March 2009
Math riddle
There is a lot going on at the moment - time for a short break. :)
I got this little riddle from a colleague, he told me it's a first semester math student standard.
We start with
a = b
multiplying with a we get
a^2 = ab
substracting b^2
a^2 - b^2 = ab - b^2
this is
(a+b) (a-b) = (a-b) b
now cancelling (a-b)
(a+b) = b
and as a=b (first line!)
a+a = a
hence 2a = a
or 2 = 1
Funny, isn't it :)
Have fun searching for the wrong statement.
I got this little riddle from a colleague, he told me it's a first semester math student standard.
We start with
a = b
multiplying with a we get
a^2 = ab
substracting b^2
a^2 - b^2 = ab - b^2
this is
(a+b) (a-b) = (a-b) b
now cancelling (a-b)
(a+b) = b
and as a=b (first line!)
a+a = a
hence 2a = a
or 2 = 1
Funny, isn't it :)
Have fun searching for the wrong statement.
Friday 20 February 2009
Down to the labs
There is more good news :)
It appears that we made an invention (when this is defined by something which
get's patented). Currently we construct an experimental prototype (which is real
hardware). It takes a lot of time but it is also exiting and makes a lot of fun. The details evolve along construction in discussion with the (excellent) mechanic of my
engineering chair. Next week we will start meassurements - and if all works fine
we'll try to apply for a patent.
I learned some mechanical basics before I started my first study (engineering) and
it remindes me to that times.
What is really cool, if the stuff works - it's found by optimization. Engineers are
working for quite some time to solve the problem - maybe the algorithm found it (it's not that intuitive in the first glance) ... well, let's see.
It appears that we made an invention (when this is defined by something which
get's patented). Currently we construct an experimental prototype (which is real
hardware). It takes a lot of time but it is also exiting and makes a lot of fun. The details evolve along construction in discussion with the (excellent) mechanic of my
engineering chair. Next week we will start meassurements - and if all works fine
we'll try to apply for a patent.
I learned some mechanical basics before I started my first study (engineering) and
it remindes me to that times.
What is really cool, if the stuff works - it's found by optimization. Engineers are
working for quite some time to solve the problem - maybe the algorithm found it (it's not that intuitive in the first glance) ... well, let's see.
Paper accepted
Lucky day today :)
Some time ago I got back the review of our first paper. I'm currently working on the next version, taking the comments of the reviewer into account.
What I did not post, is that we also submitted a second paper dealing with the dynamic optimization. It was submitted along the OIPE workshop. Here is the preprint. The comments of the two reviewers came today and were actually quite good (twice an "eight"). I was escpecially happy about the comment "The detailed discussion is nice." as a lot of effert went into that paper.
After working in the comments the paper will appear in a special issue (optimization and inverse problems) of the International Journal of Applied Electromagnetics and Mechanics IJAEM.
What is the paper about? It does dynamic optimization of the piezoelectric loudspeaker:
Brown is the thin metal plate (think of the "membrane" of a loudspeaker, even if the term is in this case not correct) which is excited by a thin piezoelectric layer (blue). We search for the best topology of the piezoelectric layer.
What needs to be clearified in the first paper, is that we need no volume constraint. Hence, when doing a parameter study optimizing for many frequencies from 20 to 2000 Hz
We can check what the optimal volume is and if it is really "black and white" enough. This is the special intrinsic piezoelectric feature we found and what needs to expressed in more detail for the revision of the first paper.
A typical example (800 Hz) is the following picture where blue means "no piezoelectric material" but brown means, "yes - place the pizeo here".
The paper discusses some interesting ressonance issues of piezoelectric optimization (it's special there!) and does also multiple frequency optimization. But that's much to much for a blog posting.
Some time ago I got back the review of our first paper. I'm currently working on the next version, taking the comments of the reviewer into account.
What I did not post, is that we also submitted a second paper dealing with the dynamic optimization. It was submitted along the OIPE workshop. Here is the preprint. The comments of the two reviewers came today and were actually quite good (twice an "eight"). I was escpecially happy about the comment "The detailed discussion is nice." as a lot of effert went into that paper.
After working in the comments the paper will appear in a special issue (optimization and inverse problems) of the International Journal of Applied Electromagnetics and Mechanics IJAEM.
What is the paper about? It does dynamic optimization of the piezoelectric loudspeaker:
Brown is the thin metal plate (think of the "membrane" of a loudspeaker, even if the term is in this case not correct) which is excited by a thin piezoelectric layer (blue). We search for the best topology of the piezoelectric layer.
What needs to be clearified in the first paper, is that we need no volume constraint. Hence, when doing a parameter study optimizing for many frequencies from 20 to 2000 Hz
We can check what the optimal volume is and if it is really "black and white" enough. This is the special intrinsic piezoelectric feature we found and what needs to expressed in more detail for the revision of the first paper.
A typical example (800 Hz) is the following picture where blue means "no piezoelectric material" but brown means, "yes - place the pizeo here".
The paper discusses some interesting ressonance issues of piezoelectric optimization (it's special there!) and does also multiple frequency optimization. But that's much to much for a blog posting.
Friday 16 January 2009
Books about Topology Optimization
When it comes about the SIMP method, the standard book is clearly
Bendsoe, M.P. and Sigmund, O.; Topology Optimization: Theory, Methods, and Applications; Springer; 2003 (scholar.google, amazon). Bendsoe and Sigmund are the godfathers of modern SIMP and their review book like work gives a lot of insight into various achievements and limits of the method. On the other side it is not that appropriate to hand to a studendt to get a glimpse about SIMP, especially on the basics and backgrounds.
Since a couple of weeks only there is another book available:
Christensen, P.W. and Klarbring, A.; An Introduction to Structural Optimization; Springer; 2008 (scholar.google, amazon). It covers truss optimization, SIMP but also the necessary basics in optimization mathematics (e.g. convexity, MMA, ...). I would say it is ideal for studens of computational engineering. For math students the proofs are missing but "normal" engineers should not fear math language, albeit the content is appropiate for them. The book has even exercies and gives a very good introduction to the subject.
Concerning the covered content: Background and exercises versus review like collection of applications, do these books complement each other almost ideally. One (engineer) should just read Christensen and Klarbring prior to Bendsoe and Sigmund (after browsing the later's applications as motivation :)).
Bendsoe, M.P. and Sigmund, O.; Topology Optimization: Theory, Methods, and Applications; Springer; 2003 (scholar.google, amazon). Bendsoe and Sigmund are the godfathers of modern SIMP and their review book like work gives a lot of insight into various achievements and limits of the method. On the other side it is not that appropriate to hand to a studendt to get a glimpse about SIMP, especially on the basics and backgrounds.
Since a couple of weeks only there is another book available:
Christensen, P.W. and Klarbring, A.; An Introduction to Structural Optimization; Springer; 2008 (scholar.google, amazon). It covers truss optimization, SIMP but also the necessary basics in optimization mathematics (e.g. convexity, MMA, ...). I would say it is ideal for studens of computational engineering. For math students the proofs are missing but "normal" engineers should not fear math language, albeit the content is appropiate for them. The book has even exercies and gives a very good introduction to the subject.
Concerning the covered content: Background and exercises versus review like collection of applications, do these books complement each other almost ideally. One (engineer) should just read Christensen and Klarbring prior to Bendsoe and Sigmund (after browsing the later's applications as motivation :)).
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