Architecture of the Mirrors
With its performative form, engineered to create a spatial acoustic effect whilst being structurally optimized for efficient material use, the installation “Acoustic Mirrors” showcases the potential of computational design and large scale 3D printing for construction.
The interdisciplinary project bridging physics and architecture consists of two 2 meter monolithic concave mirrors. These mirrors are designed to allow people to communicate by whispering over a large distance, making use of a physical effect which can also be found in the historic architecture of whispering galleries.
The organic and highly ornate design of the mirrors were generated through custom design software, integrating acoustic, structural and fabrication parameters. An optimal weight / strength ratio could be achieved by selectively distributing material along the flow of forces.
Using 3D printing, the resulting complex forms could be materialised in a fully automated and materially efficient fabrication process with precision at a fraction of a millimeter.
Slideshow Design
Computational Design
The project Acoustic Mirrors uses computational design for form finding. The design is entirely generated within custom software that integrates a structural optimization program and acoustic simulation software. This workflow facilitates a deep study and evaluation of several design variations, while integrating multiple design criteria into the design. In addition, the parametric design tool developed for this project allows the design of both the overall structures and the small scale details in a coherent process, finally offering the direct export of the final fabrication data.
Print Slices
Digital Fabrication through 3D Printing
Additive Manufacturing for construction
For the first time, 3D binderjet printing was used to create a large scale outdoor installation made from artificial sandstone. The two mirrors are some of the largest parts printed with binder jetting. Compared to fabrication based on cast concrete, direct additive manufacturing has key advantages.
- Formwork free fabrication: The process does not require formwork, hence reduces waste and cost in the fabrication process.
- Material efficiency: No material needs to be milled and material is only used where needed, while unused material can be recycled.
- Customization: Using 3D printing for construction promises to fabricate customized elements without generating extra cost.
- Complex Geometry: With 3D printing, complex geometries can be efficiently fabricated that might otherwise require multiple, time- and labour-intensive fabrication steps, or could even be impossible to fabricate otherwise.
Binderjet printing
Binderjet 3D printing follows a procedure which is repeated layer by layer with an increasing height. In the first step, loose sand is evenly distributed along the full print bed. In the second step, a 2D pattern of binder is printed which selectively bonds the sand together with the lower layers. Among the various 3D printing strategies, binderjet printing offers specific advantages for construction:
- High resolution: Features can be printed in a resolution at a fraction of a millimeter
- Large dimension: Large print-bed of up to 4x2x1m
- Highest geometric freedom: Cantilevering and hollow geometries are possible as the loose sand acts as support during the printing process
- Fast print speed: Fabrication time is independent from the complexity of the geometry due to fullwidth industrial printheads.
- Low cost: Material costs are significantly lower compared to other high resolution printing strategies
Each acoustic mirror could be printed with the largest industrial 3D binderjet printer with a print-bed of 4x2x1m and a layer height of 0.3 mm in less than 48 hours.
Functional coating
As the surface of printed sandstone is porous and fragile, for an outdoor application, several coating strategies were investigated. The selected sprayed sealant with a thin layer of polyester resin protects the structure against the weather. Structural tests have also shown that the 3D printed parts can be dramatically strengthened through the resulting composite material system. A final coating of a bright layer of color reveals all the details and ornament of the installation and guarantees high contrast and shadowplay under sunlight.
Please find more information about the team of the Acoustic Mirror in the imprint.