We’ve previously reported on the use of filament winding technology as a way of fabricating architectural composites in the 2012 ICD-ITKE Research Pavilion. [http://compositesandarchitecture.com/?attachment_id=1387]A couple of years before that, Belgian designer Peter Donders appropriated the same industrial technique for a smaller-scale, but somewhat more practical application.
The 2010 C-Bench, and its accompanying C-Stone, are carbon-fiber windings. The bench is 3 m (9.8 ft) long, and weighs just 5.7 kg (12.6 lbs). The seemingly haphazard criss-crossing of carbon fibers is actually a completely computer-defined winding path for a single, very long carbon fiber band, which was meticulously wound by a CNC machine. The stone is about 1.6m x1.15 m (5.3 ft x 3.8 ft) and weighs 6 kg (13.2 lbs).
It was a collaboration with Seifert and Skinner & Associates (SSA), “who specialize in developing equipment and software for bespoke automated processes,” according to Donders. SSA had experience fabricating carbon fiber/epoxy resin artefacts using filament winding. The resin-impregnated fiber band is wound around a mandrel and heat-cured to harden the resin. Then the mandrel is removed, leaving the carbon fiber windings defining the shape where the mandrel used to be.
This technology is usually used for industrial purposes like winding pressure vessels, where the winding is often densely multilayered. Donders goes completely in the opposite direction, using it as minimally a possible.
Donders’ describes the design and development process:
Overall shapes for C-Bench and C-Stone were developed in the NURBS (Non-Uniform Rational B-Spline) based programme Rhino in April 2010. The software also allowed for the generation of CAD/CAM data to drive a 5-axis CNC mill in manufacturing the tool (mandrel) that the fibres were ultimately wound on. Rhino’s T-Spline plugin was also used to add detail, create nonrectangular topology and edit complex freeform models whilst maintaining NURBS compatibility.
To achieve the concept of forming the structures from a single uninterrupted wound filament over an organically flowing surface, an exact description of one continuous geodesic path over the complex surface of the base-shape was required. This was generated by manipulating a chain of smoothly linked multiple geodesic paths until they all described a single route, using the geodesics function to define a start point, end point, and base surface in Rhino’s Grasshopper plugin. After extensive experimentation and changes in the used algorithms, a method was found which generated the continuous path on the surface. Using variations in the parameters of the algorithms and semi-automatic selection of the individual circuits, the desired look could finally be achieved. The final design stage challenge was to get the path data out of Grasshopper in a form that could be utilized by the computer controlled filament winding machine. This was achieved by exporting the path data in a .csv (Comma Separated Values) format into the CNC software for the filament winding machine.
In late August 2010 the first prototypes were made. Structural testing on a scale model form of the C-Bench returned successful results, and as soon as the big moulds were ready, final full-scale versions were identically fabricated. Using this process, it is proposed to manipulate the filament path to a different configuration for each iteration. As required for construction purposes, it can be decided during the design process where to put more – or less – material and control the locations as well as the number of fibre crossings, both of which will determine the maximum carry load of the object. SSA’s filament winding facilities can accommodate objects up to 1500mm x 9000m.
With an object like this, the Fun Facts are hard to resist: The bench is made of a single, continuous band of carbon fiber 320 m (1050 ft) long. To put that in perspective, that’s reaches from the tip of New York’s Chrysler Building down to the ground. The band consists of six 24K tows of fiber, 144,000 individual filaments. Put them all end-to-end, 46,080 km (28,633 mi) long, and they would wrap once around the Earth and go an extra wind across North America.
The larger picture is that, unlike many composite objects, this approach to composite construction is not so much about creating a surface as it is about defining a surface conceptually where there is very little tangible surface at all. There is also a certain deliciousness in being able use all this highly precise technology to create something that conveys almost randomness, a flirtation with chaos. That is a technological achievement as well as an artistic one. The extraordinary strength of carbon fiber makes a huge contribution to that achievement, allowing the bench and stone to reach an extreme degree of spareness and still function as weight-bearing objects.
Images courtesy of Peter Donders