Programmable materials for vibration technology-related optimization.

PROGRAMMABLE MATERIALS, MICROMECHANICS

Fraunhofer Programmable Materials research cluster. (© iStock)

The Fraunhofer Programmable Materials research cluster is dedicated to the development of materials whose structure is designed to enable targeted inspection and reversible change of their properties. Programmable materials have the potential to introduce a paradigm shift in the handling of materials, whereby they replace technical systems comprised of many components and materials with an individual, locally configured material. This allows for the implementation of complex and locally diverse effects which enable completely new component functions.

The future of materials

According to the vision of the Fraunhofer researchers, the future of materials is in combining logic and material itself. Functionalities are directly programmed into the structure of the material, thereby replacing complete systems including sensors, actors and energy supply. This opens up unique potential for new system solutions. Scientific foundations are currently being laid in the research cluster and, in conjunction with industry, potential applications identified. Indeed, through the intensive contact with numerous industry partners in relation to dynamic issues, Fraunhofer LBF can make a valuable contribution here.

Figure 1: Unit cells with strain-dependent damping with acoustic sub-structure.
(© Fraunhofer LBF)

Figure 2: CAD model of a unit cell for acceleration-dependent damping.
(© Fraunhofer LBF)

Figure 3: Macroscopic function demonstrator of a unit cell for acceleration-dependent damping. (© Fraunhofer LBF)

Programmable damping

Many applications require frequency or situation-dependent damping, which are currently carried out through either fixed passive measures or labor-intensive active systems. Therefore, the research cluster researched approaches for programmable materials whose dynamic damping properties can be changed independently and reversibly depending on the situation. This means that materials which are normally rigid but become soft and highly absorbent in the event of a sudden collision with high accelerations, for instance, to protect sensitive electronics, are conceivable. Another possibility is the designing of materials whose damping behavior depends on the current strain and thereby show optimal dynamics depending on the operating situation. Ultimately, it is possible to design materials whose temperature-dependent damping behavior is the exact opposite of that of conventional materials such as elastomers.

Design and testing of unit cells

Just as organs in the human body consist of functional units of cells, programmable materials can also be formed using unit cells. Their functionality, for example, the acceleration, strain or temperature-dependent damping, is based on micromechanical effects. This means internal flow areas are mechanically varied and the damping behavior determined.

At Fraunhofer LBF, mechanical unit cells such as these are functionally designed, macroscopically implemented as prototypes and experimentally characterized. At the same time, in collaboration with the partners from other Institutes, production methods to achieve the unit cell compounds are developed at various scales with a view to ensuring marketability in line with serial production.