wrinkling

Wrinkling - Theoretical Foundation, Experimental Characterization and Numerical Modeling

This course is aimed at graduate students, PhD candidates, and postdoctoral researchers in electronics/biomedical/mechanical/civil engineering, materials science, biophysics and applied mathematics. It is also valuable for senior scientists and engineers in academia and industry interested in the fundamental theoretical aspects of wrinkling phenomena, their numerical simulation and experimental characterization.

Petals and leaves are usually curled and exhibit intriguing morphology evolution upon growth, which contributes to their important biological functions. To understand the underlying morphoelastic mechanism and to determine the crucial factors that govern the growth-induced instability patterning in curved petals and leaves, we develop an active thin shell model that can describe variable curvatures and spontaneous growth, within the framework of general differential geometry based on curvilinear coordinates and hyperelastic deformation theory.

A highly stretched hyperelastic shell exhibits a coupling behavior of local wrinkling and global bending within the stability boundary, and curvature resists and can even suppress surface wrinkles beyond a critical threshold. Here, we report a novel phenomenon that smooth surface maintains upon stretching a soft shell, while wrinkles emerge upon unloading, which implies a nonlinear interplay between curvature and Mullins (stress softening and residual strain) effects in the entire loading-unloading cycle.

V. Slesarenko and S. Rudykh, Harnessing viscoelasticity and instabilities for tuning wavy patterns in soft layered composites. Soft Matter (2016)  DOI: 10.1039/C5SM02949J

Zheng Jia, Teng Li, Failure Mechanics of a Wrinkling Thin Film Anode on a Substrate under Cyclic Charging and Discharging, Extreme Mechanics Letters, accepted, 2016 (DOI:doi:10.1016/j.eml.2016.03.006)

PhD project 2 (Reference: NGCM-0080)

Design and optimisation of bio-inspired programmable surfaces with active materials

Biotribology Group, nCATS
Faculty of Engineering and the Environment
University of Southampton, United Kingdom

Background

PhD project 1 (Reference: NGCM-0011)

Generalised asymptotic numerical methods for buckling instability problems in biological systems and bio-inspired morphing structures

Biotribology Group, nCATS
Faculty of Engineering and the Environment
University of Southampton, United Kingdom

Background

Spatial pattern formation in stiff thin films on soft substrates is investigated from a multi-scale point of view based on a technique of slowly varying Fourier coefficients. A general macroscopic modeling framework is developed and then a simplified macroscopic model is derived. The model incorporates Asymptotic Numerical Method (ANM) as a robust path-following technique to trace the post-buckling evolution path and to predict secondary bifurcations.

F. Xu, Y. Koutsawa, M. Potier-Ferry, S. Belouettar

http://dx.doi.org/10.1016/j.ijsolstr.2015.06.007

Abstract: