Visitors to OLMA, west Switzerland’s largest agricultural fair, were treated to a rest on a 3D printed, biodegradable chaise longue.

With its ergonomic design, intricate details and its optimised geometry, the robotically 3D-printed LevisErgon chair showcases the potential of a strong interplay between digital fabrication and computational design. Consequently, the chair could be 3D-printed with a thickness of only 2mm, enabling it weight, despite dimensions of 1.7m x 0.7m x 0.7m, to be under 15kg.

Notwithstanding its great potential, plastic extrusion based 3D-printed objects tend to be heavier than parts fabricated using conventional machining or injection moulding. This is due to a fundamental limitation: the layer adhesion along the z-axis is weak. To address this limitation, one usual option is to print with a high material thickness in order to increase the inter-layer contact area.

In contrast, the design of the chaise longue LevisErgon is structurally optimised by adapting to the structural-flow that results from the physical interaction of human and object. The individual plastic layers are printed in variable layer-height and printing-speed, allowing each layer to follow computationally generated force fields. With this approach, increasing the weight can be avoided and the material can be saved while maintaining structural integrity. This first prototype was printed out of Polylactic Acid (PLA), a recyclable and biodegradable material derived from natural sources such as starch.

The computationally generated geometry showcases several design features which, apart from the unique aesthetics, also have a structural role:
• The inner, three-dimensional wave structure stiffens the millimetre-thin plastic shell
• The honeycomb-shaped holes reduce material usage
• The variation in layer-height avoids delamination along the layer-seams

The LevisErgon is developed by MAS ETH DFAB students Moon Young Jeong and Frank Cheng-Huang Lin, and supervised by Hyunchul Kwon (Digital Building Technologies, ETH Zurich) especially for their individual thesis and the ETH Zurich at the Olma Fair 2018.

Photos: Cross section: (c) Jetana Ruangjun
Hyunchul Kwon at OLMA: (c) Moon Young Jeong