Issue 8, 2016

Crack patterns over uneven substrates


Cracks in thin layers are influenced by what lies beneath them. From buried craters to crocodile skin, crack patterns are found over an enormous range of length scales. Regardless of absolute size, their substrates can dramatically influence how cracks form, guiding them in some cases, or shielding regions from them in others. Here we investigate how a substrate's shape affects the appearance of cracks above it, by preparing mud cracks over sinusoidally varying surfaces. We find that as the thickness of the cracking layer increases, the observed crack patterns change from wavy to ladder-like to isotropic. Two order parameters are introduced to measure the relative alignment of these crack networks, and, along with Fourier methods, are used to characterise the transitions between crack pattern types. Finally, we explain these results with a model, based on the Griffith criteria of fracture, that identifies the conditions for which straight or wavy cracks will be seen, and predicts how well-ordered the cracks will be. Our metrics and results can be applied to any situation where connected networks of cracks are expected, or found.

Graphical abstract: Crack patterns over uneven substrates

Supplementary files

Article information

Article type
23 Sep 2015
04 Jan 2016
First published
06 Jan 2016
This article is Open Access
Creative Commons BY license

Soft Matter, 2016,12, 2253-2263

Author version available

Crack patterns over uneven substrates

P. Nandakishore and L. Goehring, Soft Matter, 2016, 12, 2253 DOI: 10.1039/C5SM02389K

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

Read more about how to correctly acknowledge RSC content.

Social activity