Active Mechanical Metamaterials

Mechanical metamaterials are a new class of materials that allow engineering a wide range of specific properties of structures. Examples of these properties include Poisson’s ratio, stiffness, impact resistance, and coefficient of thermal expansion. These properties are defined by specific lattice structures which require additive manufacturing (AM) techniques for implementation. With the significant advances in AM, these metamaterials have become readily accessible.

When it comes to bringing these materials into applications, there is a huge solution space – coupled with multiphysical requirements and constraints. Additional design possibilities come into play when metamaterial structures are equipped with feedback control. This makes the design of components with mechanical metamaterials a complex task.

“How can we design and implement functional structures featuring
active mechanical metamaterials from a holistic perspective?”

We investigate and characterize active mechanical metamaterial concepts and on the one hand. On the other hand, we develop suitable types of structural design and computational methods for holistically engineer components.

To achieve a wide range of mission objectives, satellites are equipped with high-precision instruments. In the case of earth observation missions, these are high-resolution image sensors with an associated optical system. These instruments are subject to significant thermal loads from radiation (e.g. solar radiation) and the satellite environment. This leads to distortions in such instruments due to thermal expansion, which has a negative impact on performance.

Here, we use thermoelastic metamaterials combined with feedback control to mitigate these deformations. Thermoelastic metamaterials are a special class of mechanical metamaterials that allow the design of specific thermal expansion behaviour of components. In particular, negative thermal expansion is possible. This is achieved by combining two materials with different thermal expansion coefficients in complex lattice structures. They are becoming available with the advent of multi-material additive manufacturing. Suitable feedback control algorithms have been developed at the Institute of Space Technology & Space Applications.

Within this project we are focusing on the following:

• Developing appropriate types of structural designs and design methods for dimensionally stable structures with active thermoelastic metamaterials.
• Developing an in-orbit demonstration experiment to be launched on the SeRANIS mission.

Our work is done in close collaboration with the Institute of Materials Science.

This project is part of the dtec.bw project SeRANIS. SeRANIS is funded by dtec.bw – Digitalization and Technology Research Center of the Bundeswehr which we gratefully acknowledge. dtec.bw is funded by the European Union – NextGenerationEU.