- Other Conference Item
Rights / licenseIn Copyright - Non-Commercial Use Permitted
Mechanical metamaterials are cellular structures with architected geometries resulting in a range of properties not found in natural materials. This class of structures is gaining increased interest for use in morphing systems, where extreme displacements are sought in order to produce variable geometries for increasing structural efficiencies in a changing environment. Recent research has demonstrated that mechanical metamaterials can be realized from thin, yet stiff, fiber-reinforced polymers shells, offering an extremely lightweight solution for morphing in load-carrying applications. However, lightweight, energy-efficient actuation of these systems has yet to be addressed. In particular, methods of limiting the required actuation effort as well as leveraging the periodic/aperiodic nature of metamaterials for actuation remain open questions. In this work, a unit cell of a thin shell-based composite metamaterial with a chiral geometry is analysed to address these gaps. First, bi-stability is built into the unit cell in order to eliminate the need for continuous power input for actuation by replacing the, typically, flat shell members with cylindrical shell sections. These shells are manufactured to be pre-stressed due to thermal mismatch of their constituent materials, thereby resulting in two stable states. It is well known that such bi-stable shells are highly sensitive to boundary conditions. As a result, a study of the required boundary conditions to allow bonding of these shells into metamaterials geometries is carried out. The resulting bi-stable structure is combined with materials exhibiting the shape memory effect to achieve actuation between the stable modes. Most significantly, continuous energy input is not required to maintain either stable state. Finally, the complex geometry of the unit-cell, which contains several bi-stable elements, is used to achieve multi-stability. It is demonstrated that the metamaterial concept can be leveraged to result in a high number of stable states using only bi-stable elements – exceeding the performance of many existing active systems. The minimization of the required number of actuators to achieve this performance is examined in this work. Show more
PublisherETH Zurich, Laboratory of Composite Materials and Adaptive Structures
Organisational unit03507 - Ermanni, Paolo / Ermanni, Paolo
NotesDue to the Coronavirus (COVID-19) the workshop was conducted virtually.
MoreShow all metadata