Marcelo A F Gomes | Searcharxiv

arXiv2021

Unfolding of Crumpled Thin Sheets

Crumpled thin sheets are complex fractal structures whose physical properties are influenced by a hierarchy of ridges. In this Letter, we report experiments that measure the stress-strain relation and show the coexistence of phases in the stretching of crumpled surfaces. The pull stress showed a change from a linear Hookean regime to a sublinear scaling with an exponent of $0.65 \pm 0.03$, which is identified with the Hurst exponent of the crumpled sheets. The stress fluctuations are studied, the statistical distribution of force peaks is analyzed and it is shown how the unpacking of crumpled sheets is guided by long distance interactions.

cond-mat.soft↗

arXiv2017

Unpacking of a crumpled wire from two-dimensional cavities

The physics of tightly packed structures of a wire and other threadlike materials confined in cavities has been explored in recent years in connection with crumpled systems and a number of topics ranging from applications to DNA packing in viral capsids and surgical interventions with catheter to analogies with the electron gas at finite temperature and with theories of two-dimensional quantum gravity. When a long piece of wire is injected into two-dimensional cavities, it bends and originates in the jammed limit a series of closed structures that we call loops. In this work we study the extraction of a crumpled tightly packed wire from a circular cavity aiming to remove loops individually. The size of each removed loop, the maximum value of the force needed to unpack each loop, and the total length of the extracted wire were measured and related to an exponential growth and a mean field model consistent with the literature of crumpled wires. Scaling laws for this process are reported and the relationship between the processes of packing and unpacking of wire is commented upon.

cond-mat.soft↗