The Mechanics of Crumpled Thin Sheets Simon de Villiers, PGP, University of Oslo
Why Crumpled Paper? Ubiquitous Phenomena
Why Crumpled Paper? Ubiquitous Phenomena Power law statistics
Why Crumpled Paper? Ubiquitous Phenomena Power law statistics Self affine geometry
Why Crumpled Paper? Ubiquitous Phenomena Power law statistics Self affine geometry Contact area of rough surfaces
Why Crumpled Paper? Ubiquitous Phenomena Power law statistics Self affine geometry Contact area of rough surfaces Convenient in the laboratory
Balance Crumpled film Heavy stone table Computer controlled micrometer screw gauge Perspex plate Experimental Setup
Stress Relaxation
Stress Strain Relationship x cm circle of crumpled cellophane compressed 0.1mm every minute Time in seconds (incremental strain increase of 0.1mm per minute) Balance reading in grams (stress)
Stress Strain Relationship x cm circle of crumpled cellophane compressed 0.1mm every minute x Time in seconds (incremental strain increase of 0.1mm per minute) 16cm circle of crumpled cellophane compressed 0.1mm every minute Time in seconds (incremental strain increase of 0.1mm per minute) Balance reading in grams (stress)
Regularly Folded Paper
Single Point Forcing Response
3D Imaging
Summary The importance of crumpled disorder in thin sheets. Logarithmic relaxation of stress. Exponential increase of stress with strain. Linear increase of stress with strain for ordered/simple systems.
Geological Relevance Frictional processes Thin elastic sheet dynamics in geological systems Rough surfaces
Friction in the Experiment
Repetition of the Experiment