I started to work with stress constraints. It's pretty interesting and up to now more stuff seems unclear to me that being clarified.
I read a bunch of papers, but need to read the original Duysinx and Bendsoe; Topology optimization of continuum structures with local stress constraints; 1998 paper again (maybe there are the answers to my questions hidden :)). Our results are in good agreement with the standard solutions, so our approach seems to work. However, the results of Le; Stress-based topology optimization for continua; 2010 are really extraordinary good, unmatched by any other publication I read and far better that our results.
I still wonder, why
min vol
s.th. stress constraint
works. At least for qp-regularization (Bruggi; On an alternative approach to stress constraints relaxation in topology optimization; 2008) rho_min should be the global optimum. But the results are all similar to the compliance solution. I cannot imagine, that the regularization just hides this global optimum as we use a second order optimizer ... well, I hope I'll find out.
The next thing is, that beside Le, all (of what I read up to now) published results show some grayness embedded in full material. What happens if we have to map to manufacturable black and white topologies? I have not found any discussion of this grayness yet.
8 comments:
Did you make progress on that?
Greetings from the students-laboratory :-)
Peter
Indeed, I have two initial ideas meanwhile, still the time is lacking :(
Are u including the void elements along the innerboundary (L-bracket) in your design filtering scheme?
I mean density filter
I actually don't understand what you mean. The whole domain is design domain and I consider only the true neighbor elements.
You mean to consider a "virtual" neighbor over the boundary as zero-density material but reflect it for the number of elements? That would mean one considers elements at Dirichlet boundaries as solid. Wasn't it in Ole Sigmund's morphology paper written like it? Well, I don't do it. Do you think, it makes a difference for the stress optimization result? It would surprise me, but on the other side is this stress optimization stuff tough stuff :(
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