reabsorption – the process of absorbing something again
Oxford Languages – Google Dictionary
1. Goal
- making acoustic panels from moulded recycled paper with optimal topology (in terms of sound scattering and absorption)
- composing a versatile pattern that treats a wide range of frequencies with only 1-3 types of moulds
- using Grasshopper and dedicated plugins as a helping tool for the whole design process
- topology design
- topology acoustics analysis (Pachyderm)
- mould design
- assembly simulation (Wasp)
2. Approach
Evolutionary optimization combined with acoustic analysis is unaffordable time- and resource-wise.
This is why Grasshopper with Pachyderm acoustics analysis plugin were used to manually test several topology designs for best scattering properties and then further optimize the best option.
2.1. Panel designs
The repeatable pieces were created using Grasshopper and basic Rhino geometry as parameters, making sure the pieces fit together.
- non-variable patterns (control group)
- variable patterns
- random patterns
2.2. Testing the panels
Fixed parameters: size and shape of room, speaker and receiver position, material absorption coefficients and other acoustic analysis settings, panels placement number, thickness and approximate size
Variables: Panel topology
2.3. Pattern Assembly with the Wasp tessellation plugin
3. Acoustic analysis – scripting
Input: speaker, receiver, room and panels geometry, materials coefficients (coefficients need to be set in Rhino; as no data on the exact type of shredded, recycled paper could be found, coefficients from studies on similar materials were used – links below)
Analysis methods (ray tracing and image source) and relevant settings:
ray count around 25x room volume, the higher the settings, the more precise (but longer) calculation
Output: reverberation time – the lower the more effective topology
3.1. First results
returned values negligibly similar with reverberation time varying just by 0.01-0.05 sec
3.2. Changing parameters
- analysis settings, speaker and receiver placement, room geometry and panel types systematically to find the error;
- tried applying Rhino geometry as well as Grasshopper-created one;
- differences between panel samples within the same setting trials still negligibly similar
3.3. Bigger scale and problem with meshes
up-scaled the room and used maximally different absorbing geometries (to test if script returns any results at all);
Unfortunately, somewhere during changing the settings “problem with meshes” error started appearing and I was unable to tell what the problem was.
3.4. New acoustics script
After rewriting the script, the calculations were running considerably slower than in the previous attempts;
tried using a different computer with higher RAM in case the problem was my machine; tried other Rhino versions, too.
Unfortunately, the analysis still exceeded reasonable calculation time. This depleted my options for further exploration of the problem.
4.5. Summary of results
The overall process returned results which differed very slightly. Yet, I’m not able to tell whether that’s an issue of the script, the input geometry or the panels design being insufficient.
7. Pachyderm for Rhino
Besides Grasshopper, Pachyderm operates in Rhino itself as well. I tried this option, too, in addition to the scattering analysis option, that, although still an experimental part of Pachyderm, is available there.
Tried on the other computer as well.
These attempts, however, returned similar results to the ones before.
8. Wasp tessellation
Finally, I also created a simple tessellation script using the Wasp plugin. It previews the complete composition of panels on a custom wall, avoiding obstacles like windows and doors, and gives the number of panels needed, based on the size of the pieces.
9. What’s next
The script could be rewritten again, following one of the tutorials available online (link below), to avoid any issues with geometry, computation time or mistakes that were overlooked. It might also work better in the Rhino 8 version, once it is fully developed and stable. If the issues were to be overcome, the process could be further developed, possibly expanded to generative design and automated optimization
Overall, however, Pachyderm provides a very useful tool for the still new computational design in architecture. The plugin is definitely worth exploring, developing and looking for its potential new applications, also in combination with other add-ons.
Many thanks to the authors of both plugins for their work developing and providing these tools for free.
Links:
Pachyderm tutorials:
https://vimeo.com/groups/824140
Material studies and coefficients:
https://www.researchgate.net/publication/311977964_Sustainable_Panels_with_Recycled_Materials_for_Building_Applications_Environmental_and_Acoustic_Characterization
https://www.sciencedirect.com/science/article/pii/S0048969721025328