Bistable Heterogeneous Reconfigurable Mechanical Metamaterials

In recent years, significant advances have been made on materials that can perform multiple functions through reconfiguration or shape adaptation. However, several key limitations, such as i) low morphing speed (e.g. they use swelling or thermally-induced phase transitions), ii) low stiffness per unit mass, iii) irreversibility, and/or, iv) limited reconfigurability (magnitude of the change, or the number of shapes that can be achieved) remain.<br/> <br/>Within the context of engineered materials and structures for aviation systems, there are several avenues that could be considered to provide significant performance improvement, namely 1) improving specific strength or stiffness per unit mass of the materials used in the system design, 2) creating greater efficiency by rearranging existing materials into new structural configurations, or 3) introducing materials capable of performing multiple functions simultaneously through reconfiguration, thereby reducing the number of sub-systems needed. While the first two avenues are the most common, this research is focused on the third avenue. Taking inspiration from a dream morphing material such as Hollywood’s shapeshifting liquid metal of the T-1000 in the Terminator franchise, we strive to achieve a material that would surpass the aforementioned limitations.<br/> <br/>While current-state-of-the-art small unmanned aviation systems (sUAS) do offer good maneuverability or endurance, they lack the ability to switch between the two or do both, in contrast to biological analogs, which in addition also have specialized capabilities such as perching. Such combined varied abilities, typically enabled by shape adaptation of the system’s structure and variation of mechanical properties would greatly enhance capabilities by providing a paradigm shift in how such systems operate. This research presents a materials-based approach to transform current sUAS capabilities in both respects, the maneuverability and endurance domains, by way of shape adaptation<b>. </b><br/> <br/>Specifically, we discuss leveraging the inherent multistability of the architected microstructure in combination to heterogeneity and stimuli responsivity to develop advanced 4D-printed reconfigurable materials for application in future sUAS with capabilities that could approach, and potentially exceed, the performance of biological systems.