Design and testing of a low-energy and -carbon prototype structure that adapts to loading through shape morphing

Abstract

This paper presents an experimental validation of a new design method for adaptive structures that counteract the effect of loading through shape morphing. The structure is designed to morph into target shapes that are optimal to take external loads through combined optimization of structural layout and actuator placement. The prototype tested in this study is a simply supported spatial truss that spans 6.6 m with a span-to-depth ratio of 44/1. Shape adaptation is achieved through controlled length changes of 12 linear actuators that are strategically integrated into structural elements. A new mechanics-based framework has been formulated to enable real-time control. Linear-sequential shape optimization is employed to predict target shapes under loading. Actuator commands are computed through an iterative process that accounts for geometric nonlinearity. This formulation allows a reduction of computation time by four orders of magnitude compared with a nonlinear programming formulation. Experimental testing has shown that significant stress homogenization is achieved through shape adaptation, which results in up to 45% savings of material mass compared with a weight-optimized passive structure. Depending on the energy source employed for adaptation, the equivalent carbon is reduced by up to 29% and 43% in the case of non-renewable and 100% renewable energy mix, respectively.