PAN_07 CHAIR
optimised cellular structure

date: 2007
(collaboration with Timothy Schreiber)

Based on an analogy with the highly efficient cellular structure of living wood or bone, which adapts to its environment as it grows, the chair's interior is comprised of a fine lattice that minimises weight while maximising strength. The design method combines principles of evolution and artificial intelligence to create a material that responds to its environment by growing denser in the areas required to best withstand the external forces applied when the chair is in use.

The composition of the cells is the result of a computational process directly modelled on nature that creates a modular space frame structure of tiny interconnected struts, specifically suited to the material and fabrication process. A genetic algorithm, using the principles of natural evolution, has been used to generate the topology of the structural cells. Using machine learning techniques each one is given just enough intelligence to reorient itself or change its shape, size or structure depending on where it sits in the body of the chair. A section through the vertical leg of the chair, for example, reveals cells with a greater density toward the surface to counter the higher tensile or compressive stresses that result as it bends.

This internal structure represents a new approach to materials made possible by high resolution digital fabrication technology, whereby properties can be customised to suit the object being designed.
It has broad implications in terms of our concept of materials, emphasising continuity and gradual transition over a traditional assembly of parts. The technology currently operates at the millimetre rather than the nanometre scale, but to a degree these technologies can free the designer from having to select from a pre-existing palette of materials and allow one to specify any density, Poisson's ratio or dynamic anisotropy desired. More importantly, these properties can seamlessly blend from one to the next without joints, gaps or mechanical fixing.

The sintered nylon prototype detail is comprised of approximately 50,000 individual and unique structural units, a small portion of the millions that would form the entire chair. Current research is underway to streamline the flow from optimisation to fabrication, so that objects of such complexity may be customised in real time.