It's pronounced nucular. Nu-cu-lar. -- Homer Simpson (and George W.)
- Cirriculum_vitae.pdf
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A summary of scientific work carried out during my PhD studies is given below.
Crumpled wires in 2D
In this work, we studied experimentally and using simulations the morphologies into which wires fold when inserted into a flat cylindrical cavity. Three different morphologies emerge depending on friction and the degree of plastic yielding, as shown in the picture below.
The video below shows the time evolution of one of the three morphologies.
Related Publications
Morphological phases of crumpled wire, N. Stoop, F.K. Wittel, H.J. Herrmann, Phys. Rev. Lett., 101, 094101, featured in Physics Today, Aug. 2008, as a PRL cover image and in the German FAZ (2008)
Anisotropic growth of thin shells
Growth process are ubiquitous in nature. In this work, we consider the anisotropic, circumferential growth of a thin, flat disc, which gained attention recently and was shown analytically to lead to symmetric potatoe-chip shapes termed e-cones. Our results show that under the influence of surface self-contact, symmetry breaking occurs, leading to new, asymmetric shapes.
The video below shows the symmetry breaking due to self-contact.
Related Publications
Self-contact and instabilities in the anisotropic growth of elastic membranes, by N. Stoop, F. K. Wittel, M. Ben Amar, M. M. Müller, and H. J. Herrmann, Phys. Rev. Lett. 105, 068101 (2010)
Packing of elastic rods in spherical cavities
In this ongoing research, we investigate the packing of elastic rods in spherical containers. We found that as a function of internal mechanical torsion (twist), disordered as well as ordered structures emerge, with strongly different macroscopic properties. We simulate the process using an efficient discrete element model. Together with M. Habibi and J. Najafi from Zenjan University, we found excellent agreement between simulations (left) and experiments (right):
A video of the ordered packing process is shown below:
In this video, a reduced wire diameter is displayed for better visualization. Repulsive forces due to self-contact are calculated on the effective wire diameter.
Related Publications
Packing of elastic wires in spherical cavities, by N. Stoop, J. Najafi, M. Habibi, F.K. Wittel, and H.J. Herrmann, Phys. Rev. Lett. 106, 214102 (2011)
