• Creating the Future

    The Hector Fellow Academy initiates innovative research projects on latest scientific problems.

Mechanical Metamaterials

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

The postdoc Dr. Muamer Kadic and the doctoral student Claudio Findeisen, both from the Karlsruhe Institute of Technology, work together in this project of the Hector Fellows Peter Gumbsch and Martin Wegener. They investigate the properties of novel metamaterials.

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. They 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, they 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).

Publications of this Project

1.  Kern C., Schuster V., Kadic M., and Wegener M., Phys. Rev. Appl., DOI: 10.1103/PhysRevApplied.7.044001 (2017).
2.  Qu J., Kadic M., Naber A., and Wegener M., Scientific Reports, DOI: 10.1038/srep40643 (2017).
3.  Findeisen C., Hohe J., Kadic M., and Gumbsch P., J Mech Phys Solids, DOI: 10.1016/j.jmps.2017.02.011 (2017).
4.  Kern C., Kadic M., and Wegener M., Phys. Rev. Lett., DOI: 10.1103/PhysRevLett.118.016601 (2017).
5.  Frenzel T., Findeisen C., Kadic M., Gumbsch P., Wegener M., Adv. Mater., DOI: 10.1002/adma.201600610 (2016).
6.  Schittny R., Niemeyer A., Mayer F., Naber A., Kadic M., and Wegener M., Laser Photonics Rev., DOI:10.1002/lpor.201500284 (2016).
7.  Kadic M., Bückmann T., Schittny R., and Wegener M., Phil. Trans. R. Soc. A, DOI: 10.1098/rsta.2014.0357 (2015).
8.  Kadic M., Schittny R., Bückmann T., Kern C., and Wegener M., Phys. Rev. X, DOI: 10.1103/PhysRevX.5.021030 (2015).
9.  Bückmann T., Kadic M., Schittny R., and Wegener M., PNAS, DOI: 10.1073/pnas.1501240112 (2015).
10. Schittny R., Niemeyer A., Kadic M., Bückmann T., Naber A. and Wegener M., Optica, DOI: 10.1364/OPTICA.2.000084 (2015).
11. Bückmann T., Kadic M., Schittny R., and Wegener M., Phys. Status Solidi B, DOI: 10.1002/pssb.201451698 (2015).
12. Schittny R., Niemeyer A., Kadic M., Bückmann T., Naber A. and Wegener M., Optics Letters, DOI: 10.1364/OL.40.004202 (2015).
13. Kern C., Kadic M., and Wegener M., Appl. Phys. Lett., DOI: 10.1063/1.4932046 (2015).
14. Christensen J., Kadic M., Kraft O. and Wegener M., MRS Communications, DOI: 10.1557/mrc.2015.51 (2015).
15. Kadic M., Bückmann T., Schittny R., Gumbsch P., and Wegener M., Phys. Rev. Applied, DOI: 10.1103/PhysRevApplied.2.054007 (2014).
16. Bückmann T., Thiel M., Kadic M., Schittny R., and Wegener M., Nat. Commun., DOI: 10.1038/ncomms5130 (2014).
17. Schittny R., Kadic M., Bückmann T. and Wegener M., Science, DOI: 10.1126/science.1254524 (2014).