DESIGN OPTIMIZATION OF SHAPE MEMORY ALLOY-BASED ADAPTIVE BUILDING SKINS FOR THERMAL REGULATION

This paper presents a design study of adaptive skins that enable thermal regulation for buildings. The skins consist of rectangular panels that adaptively open and close driven by shape memory alloy (SMA) wires in response to the variation of the environment temperature. The SMA wires are used as both thermal sensors and actuators that inspect the environmental temperature and provide a corresponding actuation response. When temperature is low, the SMA wires are stable in their elongated martensitic configuration, keeping the panels closed to maintain the building interior warm by reducing incoming airflow from the exterior. When temperature reaches the SMA austenite transformation values, the SMA wires transform into their contracted austenitic configuration and open the panels. This permits cooling of the building interior by allowing circulation of incoming airflow from the exterior. This repeatable response allows the skins to adaptively regulate the indoor temperature. The performance of the adaptive skins is evaluated using finite element analysis. Metallic and laminated fiber-reinforced composite plates are explored as material options for the panels. The adaptive skins are parameterized using design variables including the dimensions of the panels, the ply thickness and orientation angles in the case of fiber-reinforced panels, and the radii of the SMA wires. By employing genetic algorithms, these design variables are optimized to maximize the achievable opening area of the panels while satisfying material failure constraints.