Functional flexibility: The potential of morphing composites
Mitchell P. Jones, Gokul G. Murali, Frédéric Laurin, P. Robinson, Alexander Bismarck
Abstract
From plants tracking the sun to the aerodynamics of bird wings, shape change is key to the performance of natural structures. After years of reliance on mechanical joints, human engineering now focuses on improving aerodynamic efficiency through smooth, full form changes in material geometry, achieved using technologies such as morphing composites. Promising improved power generation and efficiency in wind turbines and safer more sustainable aircraft and cars, these materials can achieve both large geometric changes with low energy requirements by cycling between several stable physical states and more gradual changes in geometry by exploiting coefficient of thermal expansion mismatch and structural anisotropy, shape memory polymers and 4D printing. The merits and limitations of these various shape change systems are the subject of extensive and ongoing academic research and both commercial and defence industry trials to improve the viability of these technologies for widespread adoption. Shape change capabilities are often associated with problems in material cost, mass, mechanical properties, manufacturability, and energy requirements. Nonetheless, the considerable and rapid advances in this technology, already resulting in successful trials in advanced civilian and military aircraft and high-performance cars, indicate that future research and development of this materials platform could revolutionise many of our most critical power generation, defence and transport systems.