• Die Zukunft mitgestalten

    Die Hector Fellow Academy stößt innovative Forschungsprojekte in neuen wissenschaftlichen Fragestellungen an.

Mechanische Metamaterialien

Claudio Findeisen – Hector Fellow Peter Gumbsch
Dr. Muamer Kadic – Hector Fellow Martin Wegener

Der HFA Postdoktorand Dr. Muamer Kadic (Karlsruher Institut für Technologie, Institut für Angewandte Physik) und der HFA Doktorand M.Sc. Claudio Findeisen (Karlsruher Institut für Technologie, Institut für Angewandte Materialien) untersuchen die Eigenschaften neuer Metamaterialien unter Leitung der Hector Fellows Peter Gumbsch und Martin Wegener.

In contrast to classic materials, the properties of metamaterials result from their specific microstructure rather than their atomistic properties. New production methods, such as direct laser writing, allow for the production of such 3D metamaterials with microstructures in the range of micrometers, which is impossible with standard fabrication methods. In this collaboration project, the young scientists investigate the design of new classes of metamaterials. We present two classes of materials to protect from linear vibrations using cloaking devices and to absorb energy via inner instabilities of micro-lattices.

Figure 1: An elasto-mechanical unfeelability cloak made of pentamode

An elasto-mechanical “unfeelability” cloak made of pentamode metamaterials

Metamaterial-based cloaks make objects that differ from their surroundings appear just like their surroundings. To date, cloaking has been demonstrated experimentally in many fields of research. However, cloaking in the apparently simple case of three-dimensional solid mechanics is more demanding.
Inspired by invisible core-shell nanoparticles in optics, the scientists design an approximate elasto-mechanical core-shell “unfeelability” cloak based on pentamode metamaterials (see Figure 1). The resulting three-dimensional polymer microstructures with macroscopic overall volume are fabricated by rapid dip-in direct laser writing optical lithography. The researchers perform quasi-static experiments and map the displacement fields by autocorrelation-based analysis of recorded movies.

Figure 2: A shock absorber using tailored buckling micro-lattices

Tailored buckling micro-lattices as reusable light-weight shock absorbers

Structures and materials absorbing mechanical (shock) energy commonly exploit either viscoelasticity or destructive modifications. Based on a class of uniaxial light-weight geometrically nonlinear mechanical micro-lattices and using buckling of inner elements, we achieve either a sequence of snap-ins followed by irreversible hysteretic – yet repeatable – self recovery or, alternatively, multi-stability enabling programmable behavior. Proof-of-principle experiments on three-dimensional polymer micro-structures are done (see Figure 2).

Publikationen aus dem Projekt

1. Frenzel T., Findeisen C., Kadic M., Gumbsch P., Wegener M., Adv. Mater. (2016), DOI: 10.1002/adma.201600610.
2. Findeisen C., Hohe J., Kadic M., and Gumbsch P., “Characteristics of mechanical metamaterials based on unstable cells”, (in preparation).
3. Findeisen C., Hohe J., Gumbsch P., “Numerical homogenization of mechanical metamaterials based on an effective micromorphic continua” (in preparation).
4. Qu J., Kadic M., Naber A., and Wegener M. “Micro-Structured Two-Component 3D Metamaterials with Negative Thermal-Expansion Coefficient from Positive Constituents” (submitted).
5. Kadic M., Bückmann T., Schittny R., and Wegener M., Phil. Trans. R. Soc. A 373, 20140357 (2015).
6. Kadic M., Schittny R., Bückmann T., Kern C., and Wegener M., Phys. Rev. X 5, 021030 (2015)
7. Bückmann T., Kadic M., Schittny R., and Wegener M., PNAS 112, 4930 (2015).
8. Schittny R., Niemeyer A., Mayer F., Naber A., Kadic M., and Wegener M., Laser Photonics Rev. (2016) doi:10.1002/lpor.201500284
9. Schittny R., Niemeyer A., Kadic M., Bückmann T., Naber A. and Wegener M., Optica, 2, 84 (2015).
10. Bückmann T., Kadic M., Schittny R., and Wegener M., Physica Status Solidi, 252, 1671 (2015).
11. Schittny R., Niemeyer A., Kadic M., Bückmann T., Naber A. and Wegener M., Optics Lett. 40 4202 (2015).
12. Kern C., Kadic M., and Wegener M., Appl. Phys. Lett. 107, 132103 (2015).
13. Christensen J., Kadic M., Kraft O. and Wegener M., MRS Communications 5, 453-462 (2015).
14. Kadic M., Bückmann T., Schittny R., Gumbsch P., and Wegener M., Phys. Rev. Appl. 2, 054007 (2014).
15. Bückmann T., Thiel M., Kadic M., Schittny R., and Wegener M., Nat. Commun. 5, 4130 (2014).
16. Schittny R., Kadic M., Bückmann T. and Wegener M., Science 345, 427 (2014).