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Programmable Metastructures

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We study reprogrammable structures by incorporating functional composite elements into metamaterial geometries with a focus on robust shape and stiffness adaptation in structures. The research focuses on creating functionality in large structures that is more than the sum of the functionality of the individual elements.

Highly Multi-stable Surfaces

Variable Stiffness Lattices


Highly Multi-stable Surfaces

Highly multistable composite metamaterials

There is significant interest in the realization of highly multi-stable fiber reinforced polymer composite surfaces to enable energy-efficient shape adaptation. The periodic extension of bi-stable composite unit cells is a common approach to the realization of this behavior. In practice however, this is severely limited due to interaction between boundary conditions between neighboring unit cells. Instead, we investigate the shaping of composite grids using soft pre-stretched elastic membranes. The resulting surfaces show high-displacement shape-adaption, are not sensitive to boundary condition interactions between cells, and exhibit enhanced multi-stability in the periodic structures as compared to the unit cell. We are particularly interested in exploring the following aspects of these structures:

  • The effect of the composite material anisotropy on the multi-stability of the structures
  • Integration of lightweight actuation into the structures and reduction of actuation effort in large structures
  • Efficient modelling of highly multi-stable structures

Collaborators:

  • Dr. P. Ermanni and G. Risso at CMASLab, ETH Zurich

Related Publications:

  • G. Risso, T.J. Rogenmoser, M. Sakovsky, P. Ermanni, Programmable FRP metamaterials for adaptive hinges with multiple 3D shapes, AIAA 2022-1458, AIAA Scitech Forum, San Diego, USA, 2022. https://doi.org/10.2514/6.2022-1458
  • G. Risso, M. Sakovsky, P. Ermanni, Highly multi-stable pre-stretched FRP grids for shape adaptation, AIAA Scitech Forum 2021, AIAA 2021-1493, Jan. 2021. https://doi.org/10.2514/6.2021-1493

  • G. Risso, M. Sakovsky, P. Ermanni, Instability-driven shape forming of fiber reinforced polymer frames, Composite Structures 268, article no. 113946, 2021. https://doi.org/10.1016/j.compstruct.2021.113946

Funding:

  • Swiss National Science Found project funding (200021_192082)

Variable Stiffness Lattices

Enabling mechanisms is metamaterials using active bistable composites

We are interested in variable stiffness metamaterial lattices made of functional elements. Such structures can be re-programmed throughout their lifetime to respond to their environment for example to switch between load-carrying and shape adaptation capabilities. One such example are pin jointed truss structures composed of bi-stable composite elements, reversibly actuated using shape memory alloys. Here, the two stable states are leveraged for their distinct bending stiffness allowing us to program low-energy deformation mechanisms into otherwise stiff structures. Our research explores the challenges associated with these large programmable structures including manufacturing, actuation, and modelling.

Related publications: 

  • M. Sakovsky, P. Gehri, P. Ermanni, Actuation of multi-stable composite thin shell metamaterials, 26th International Conference on Adaptive Structures and Technologies (ICAST) Digital Workshop, Oct. 2020. https://doi.org/10.3929/ethz-b-000448365

Funding:

  • ETH Zurich Postdoctoral Fellowship, co-funded by the Marie Curie Actions for People COFUND Program