Smart Granular Materials: Prototypes for Hygroscopically Actuated Shape-Changing Particles

Abstract

Hygroscopically Actuated Granular Materials are a new class of designed granular materials in architecture. Granular materials are large numbers of particles that are only in loose contact with each other. If the individual particle in such a granular material is defined in its geometry and material make-up, one can speak of a designed granular material. In recent years these designed granular materials have been explored as architectural construction systems. Since the particles are not bound to each other, granular materials are rapidly reconfigurable and recyclable. Yet one of the biggest assets of designed granular materials is the fact that their overall behavior can be designed by altering the geometry or material make-up of the individual composing particles. Up until now mainly non-actuated granular materials have been investigated. These are designed granular materials in which the geometry of the particle stays the same over time. The proposed Hygroscopically Actuated Granular Materials are systems consisting of time-variable particle geometries. Their potential lies in the fact that one and the same granular system can be designed to display different mechanical behaviors over the course of time. The research presented here encompasses three case studies, which complement each other both with regard to the development of the particle system and the applied construction processes. All three cases are described both with regard to the methods used and the eventual outcome aiming at a potential design system for Hygroscopically Actuated Granular Materials. To conclude, these results are compared and directions of further research are indicated.