Is it possible to use topology optimization to add additional material to a solid structure, rather than removing material?

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Hello,

I'm trying to model a loudspeaker enclosure in 2D and use topology optimization to increase the low frequency response by adding additional material to the inside of the enclosure. My goal is a simplified version of this research article:

https://www.researchgate.net/publication/376153843_Loudspeaker_cabinet_design_by_topology_optimization

I've already simulated the initial design, but am having trouble with the optimization step. All of the tutorials I've found on topology optimization involve removal of material, not adding any additional material.

Attached are screenshots of my model and some of the results of the research paper for reference. I'm trying to add additional material to the orange fiberboard in the inner region which is occupied by air, similar to the paper. Any help or guidance would be much appreciated.



5 Replies Last Post 2024年5月16日 GMT-4 02:46
Edgar J. Kaiser Certified Consultant

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Posted: 1 month ago 2024年5月11日 GMT-4 06:35

Roland,

you can certainly add material in the optimization domain. Check the truss example in the application library to get an idea how it needs to be done.

Cheers Edgar

-------------------
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Roland, you can certainly add material in the optimization domain. Check the truss example in the application library to get an idea how it needs to be done. Cheers Edgar

Acculution ApS Certified Consultant

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Posted: 1 month ago 2024年5月13日 GMT-4 03:25

Material is added or removed, but only in the optimization domain.

-------------------
René Christensen, PhD
Acculution ApS
www.acculution.com
info@acculution.com
Material is added or removed, but only in the optimization domain.

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Posted: 1 month ago 2024年5月15日 GMT-4 03:52

Roland,

you can certainly add material in the optimization domain. Check the truss example in the application library to get an idea how it needs to be done.

Cheers Edgar

Hi Edgar,

Thanks for your response. At this point I don't have much time left to run the optimization again. However, maybe you could clarify if the method I used would be accurate:

What I've done is used topology optimization to remove air material from the inner region of the loudspeaker, which creates voids, using the edges of the enclosure as a void boundary. My understanding is that COMSOL would then treat these voids as sound hard boundaries. So, as long as the material of the enclosure is acoustically rigid enough, this should be essentially the same as adding extra enclosure material into the air domain.

I'm just curious to see how accurate the method I used would be. I went over the results with my professor who seemed to think it would be accurate enough for the scope of my project.

Thanks,

Roland Baxter

>Roland, > >you can certainly add material in the optimization domain. Check the truss example in the application library to get an idea how it needs to be done. > >Cheers >Edgar Hi Edgar, Thanks for your response. At this point I don't have much time left to run the optimization again. However, maybe you could clarify if the method I used would be accurate: What I've done is used topology optimization to remove air material from the inner region of the loudspeaker, which creates voids, using the edges of the enclosure as a void boundary. My understanding is that COMSOL would then treat these voids as sound hard boundaries. So, as long as the material of the enclosure is acoustically rigid enough, this should be essentially the same as adding extra enclosure material into the air domain. I'm just curious to see how accurate the method I used would be. I went over the results with my professor who seemed to think it would be accurate enough for the scope of my project. Thanks, Roland Baxter

Edgar J. Kaiser Certified Consultant

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Posted: 1 month ago 2024年5月15日 GMT-4 06:00

Hi Roland,

I have never done topology optimization this way, so I cannot tell if it works and gives accurate enough results. I am wondering which way the optimizer creates voids in the model and assigns a boundary condition. At the end of the day, give it a whirl and compare to a more conservative approach.

Cheers Edgar

-------------------
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Hi Roland, I have never done topology optimization this way, so I cannot tell if it works and gives accurate enough results. I am wondering which way the optimizer creates voids in the model and assigns a boundary condition. At the end of the day, give it a whirl and compare to a more conservative approach. Cheers Edgar

Acculution ApS Certified Consultant

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Posted: 1 month ago 2024年5月16日 GMT-4 02:46
Updated: 1 month ago 2024年5月16日 GMT-4 08:40

is used topology optimization to remove air material from the inner region of the loudspeaker, which creates voids, using the edges of the enclosure as a void

It is not that COMSOL treats the voids (or rather its boundaries) as sound hard walls, it is that YOU will have to interpret them as being sound hard. In the topology optimization, you have the two extremes air and "dense and 'stiff' fluid". So a very binary design, if you can get there, will have a distribuition of those extremes. There is large impedance jump going from one to the other, and so you interpret that as putting a mechanical structure where the one extreme is, and the rest is air. You will have to test in the end how well that proxy worked, especially if you final result was not very binary.

-------------------
René Christensen, PhD
Acculution ApS
www.acculution.com
info@acculution.com
> is used topology optimization to remove air material from the inner region of the loudspeaker, which creates voids, using the edges of the enclosure as a void It is not that COMSOL treats the voids (or rather its boundaries) as sound hard walls, it is that YOU will have to interpret them as being sound hard. In the topology optimization, you have the two extremes air and "dense and 'stiff' fluid". So a very binary design, if you can get there, will have a distribuition of those extremes. There is large impedance jump going from one to the other, and so you interpret that as putting a mechanical structure where the one extreme is, and the rest is air. You will have to test in the end how well that proxy worked, especially if you final result was not very binary.

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