Ruga mechanics of creasing: From instantaneous to setback creases

Mazen Diab, Teng Zhang, Ruike Zhao, Huajian Gao, Kyung Suk Kim

Research output: Contribution to journalArticlepeer-review

59 Scopus citations


We present mechanics of surface creasing caused by lateral compression of a nonlinear neo-Hookean solid surface, with its elastic stiffness decaying exponentially with depth. Nonlinear bifurcation stability analysis reveals that neo-Hookean solid surfaces can develop instantaneous surface creasing under compressive strains greater than 0.272 but less than 0.456. It is found that instantaneous creasing is set off when the compressive strain is large enough, and the longest-admissible perturbation wavelength relative to the decay length of the elastic modulus is shorter than a critical value. A compressive strain smaller than 0.272 can only trigger bifurcation of a stable wrinkle that can prompt a setback crease upon further compression. The minimum compressive strain required to develop setback creasing is found to be 0.174. If the relative longest-admissible perturbation wavelength is long enough, then the wrinkle can fold before it creases, and the specimen can be compressed further beyond the Biot critical strain limit of 0.456. Various bifurcation branches on a plane of normalized longest-admissible wavelength versus compressive strain delineate different phases of corrugated surface configurations to form a ruga phase diagram. The phase diagram will be useful for understating surface crease, as well as for controlling ruga structures for various applications, such as designing stretchable electronics.

Original languageEnglish (US)
Article number20130753
JournalProceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences
Issue number2157
StatePublished - Sep 8 2013
Externally publishedYes


  • Crease analysis
  • Finite-element analysis
  • Neo-Hookean solid
  • Nonlinear bifurcation analysis
  • Ruga phase diagram

ASJC Scopus subject areas

  • General Mathematics
  • General Engineering
  • General Physics and Astronomy


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