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Low-tech Shape-Shifting Space Frames

Low-tech Shape-Shifting Space Frames is a research done as a Master Thesis at the University of Stuttgart ITECH. This research demonstrates a system for low-tech shape-shifting space frame structures, passively responding to environmental conditions. The focus is designing simple lightweight structures that are capable of large geometrical transformations with high activation speed. The shape-shifting relies on the combination of passive wooden actuators and compliant nodes. In the proposed system, global geometrical transformations are obtained by strategically integrating passive actuators and nodes with designed compliance to create space frames that change in shape. The actuator is a hygroscopically actuated wood bilayer, that passively curves in response to the Relative Humidity (RH) fluctuation. The nodes are 3D printed with specific complaint geometries to accommodate the specific local and global transformations. Geometrical transformations are investigated through an interactive physics- based simulation and tested on physical prototypes. Low-tech Shape-Shifting Space Frames is a research presented at the 2018 IASS Conference at the MIT in Boston.

Interactive Simulation

The design strategy for low-tech shape-shifting space frame is based on an interactive simulation tool for the single hygroscopic actuator’s behavior and its effect on the global space frame. The hygroscopic actuator’s behavior is simulated following the formula for curvature calculation of bimetal thermostats adapted for wood bilayers. A geometric reconstruction of the hygroscopic actuator’s shape is obtained according to the initial parameters of length, thickness, initial and target EMC (Equilibrium Moisture Content).The hygroscopic actuator’s effect on the space frame geometry is simulated with Kangaroo 2 (K2), a live physics engine. This simulation tool converges multiple target goals in a unique solution requiring relatively low computational power in comparison to finite element analysis. The behavior of hygroscopic actuators, non-active struts and nodes are defined as specific K2 goals. The hygroscopic actuator’s shape-shifting is implemented as a custom shape-matching goal where the actuator’s shape is forced into the shape calculated with the adapted Thimoshenko’s formula.