1. The Mechanics of Crumpled Thin Sheets Simon de Villiers, PGP, University of Oslo

2. Why Crumpled Paper? Ubiquitous Phenomena

3. Why Crumpled Paper? Ubiquitous Phenomena Power law statistics

4. Why Crumpled Paper? Ubiquitous Phenomena Power law statistics Self affine geometry

5. Why Crumpled Paper? Ubiquitous Phenomena Power law statistics Self affine geometry Contact area of rough surfaces

6. Why Crumpled Paper? Ubiquitous Phenomena Power law statistics Self affine geometry Contact area of rough surfaces Convenient in the laboratory

7. Balance Crumpled film Heavy stone table Computer controlled micrometer screw gauge Perspex plate Experimental Setup

8. Stress Relaxation

10. Stress Strain Relationship 0.511.52 x 10 4 0 500 1000 1500 2000 2500 3000 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)

11. Stress Strain Relationship 0.511.52 x 10 4 0 500 1000 1500 2000 2500 3000 16cm circle of crumpled cellophane compressed 0.1mm every minute 0.511.52 x 10 4 10 -2 10 10 0 1 2 3 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)

12. Regularly Folded Paper

13. Single Point Forcing Response

15. 3D Imaging

16. 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.

17. Geological Relevance Frictional processes Thin elastic sheet dynamics in geological systems Rough surfaces

18. Friction in the Experiment

19. Repetition of the Experiment