A key influence throughout the development of our thesis work this semester has been the University of Stuttgart and the research pavilions jointly developed by the school’s Institute for Computational Design (ICD) and Institute of Building Structures and Structural Design (ITKE). The three pavilions developed from 2011 to 2014 all employed KUKA six-axis robot arms in the fabrication process, and two of them made use of carbon fiber weaving in structural and modular components. These projects were stimulating not only because they involved two key interests–robotics and composites–but also because of the rigor of the design process employed and quality of the documentation produced.
2012 Research Pavilion
Fabricated as a single unit, the 2012 pavilion uses a KUKA robot arm situated in a raised position to the side of the fabrication area to weave fiber tow onto a frame, which was removed after fabrication and installation. The design of the weaves reflects the structural forces at play in the overall design–a helicoidal crossweave is employed where strength is needed in various directions and a unidirectional weave is used to address axial forces.
This approach to weaving involving a temporary frame is of interest because of limited material required to shape the carbon fiber. A more typical approach to shaping composite materials involves single-use molds that can result in significant waste. We are interested in developing a fabrication method that will minimize waste while providing versatility and reducing the time and investment required to make use of composites.
2013-2014 Research Pavilion
The subsequent pavilion developed by the ICD/ITKE collaboration is another woven, carbon and glass fiber structure. In contrast to the 2012 pavilion, this design takes a modular approach, using a pair of robot arms to fabricate customized units for later manual assembly on site. Rather than using unique framing for each module, a single, adjustable framing system was employed, allowing for varied sizes and angles to be implemented.
In addition to the creative end-effector design, we were drawn to the design process, product and presentation of this project. It illuminates some of the technical details involved in carbon fiber weaving as well. For instance, in order to bond the carbon fiber tow to itself and to adjacent fiber tow, the tow had to be drawn through a resin bath continuously during fabrication. Unless we find an alternate form of fiber (such as “prepreg” resin pre-impregnated fiber) for any robotic weaving experiments of our own, we will have to design and construct a similar mechanism to prepare the fiber.
Both pavilions combine glass fiber with carbon fiber, using the carbon for structural reinforcement while at the same time creating a fascinating aesthetic. This approach is a more efficient use of materials, favoring the use of the more expensive carbon in areas where it is needed structurally.