Singularities in thin sheets  I
T. Witten, University of Chicago
with Hao Li, Alex Lobkovsky, Eric Kramer, Shankar Venkataramani, Brian DiDonna, Tao Liang, Sid Nagel, Kitiwit Matan ...
See also:
      http://jfi.uchicago.edu/~tten/Crumpling/
ÒStress Focusing in Elastic SheetsÓ, T. A. Witten.
Reviews of Modern Physics 79 643 (2007)
Elasticity of a thin sheet:  thin Þ unstretchable
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Singularities of unstretchable (isometric) sheets in d dimensions
vertex and ridge singularities: how stretching alters the focusing of stress
Induced singularities
interaction of singularities