Short films of quasistatic crack formation

• Simulations: 2-dimensional Spring-Block Model[1]
  (White dots are blocks. All files are in gif format. They loop automatically.)

  About the parameters: s=initial strain, kappa=material toughness, K=layer thickness.

1. 100x100, s=0.1, kappa=3, K=1, initial broken bond (bb)=10 (1.2MB)
2. 100x100, s=0.1, kappa=4, K=1: initial broken bond=0, catastrophic(161KB)
3. 100x100, s=0.1, kappa=6, K=1, initial bb=10 (1MB)
4. 100x100, s=0.1, kappa=6, K=1, initial bb=0, catastrophic(812KB)
5. 100x100, s=0.1, kappa=1, K=2: isolated diffusive cracks(950KB)
6. 100x100, s=0.1, kappa=0.5, K=3: isolated diffusive cracks, small strain (1.6MB)
7. 100x100, s=0.2, kappa=0.5, K=3, semi-isolated growth of diffusive cracks at small strain (1.5MB)
8. 100x100, s=0.3, kappa=0.5, K=3, semi-connected growth of diffusive cracks at moderate strain (1.5MB)
9. 100x100, s=0.5, kappa=0.5, K=3, connected growth of diffusive cracks at large strain (1.7MB)
10. 100x100, s=0.1, kappa=0.5, K=5: straight cracks appear (1.5MB)
11. 100x100, s=0.1, kappa=0.5, K=9: a mix of straight & diffusive (788KB)
12. 100x100, s=0.1, kappa=0.5, K=20: straight cracks dominate (776KB)
13. 100x300, s=0.1, kappa=1, K=1 to 15, a tilted sample (1.7MB)
14. 100x300, s=0.05, kappa=1, K=1 to 10, another tilted sample (759KB)
15. 100x100, s=0.5, kappa=1, K=2, straight/diffusive cracks at large strain (1.7MB)
16. 100x100, s=0.5, kappa=1, K=2, small region at 1 frame/step to show details of crack growth(4.2MB)
17. 200x200, s=0.05, kappa=1.5, K=2, a fine network of diffusive cracks (183KB)
18. 200x200, s=0.1, kappa=1.5, K=2, diffusive with some straight ones, resembling mud cracks (217KB)
19. 200x200, s=0.05, kappa=2, K=2, going from kappa=1.5 to 2 gives more straight cracks (165KB)

• Experiments: Drying of cornstarch+alcohol or water[2]
   (All files are in mpg (m1v) format.)

1. Alcohol, thin sample 0.8mm: instantaneous diffusive network with front (445KB)
2. Alcohol, 4mm: network with front (757KB)
3. Alcohol, 8.3mm: straight cr/cks (263KB), then diffusive network.(877KB)
4. Alcohol, 5x magnified: very thin sample, from evaporation to fragmentation.(487KB)
5. Alcohol, 5x magnified: thin sample, slow appearance of cracks with slippings.(733KB)
6. Alcohol, 10x magnified: details at crack surface showing grains and slippings. (471KB)
7. Water, still pictures of final configurations at various drying conditions and thickness.

• Multimedia presentation of spiral cracks[3,4]
  (Flash swf file, 2.5MB)

• References

1. Pattern formation and selection in quasi-static fracture,
   K.-t. Leung and Z. Neda, Phys. Rev. Lett. 85, 662 (2000).
2. Courtesy of Zoltan Neda.
3. Spiral cracks without twisting,
   K.-t. Leung, L. Jozsa, M. Ravasz and Z. Neda, Nature 410, 166 (2001).
   
4. Spiral cracks in drying precipitates,
   Z. Neda, K.-t. Leung, L. Jozsa, M. Ravasz, Phys. Rev. Lett. 88, 095502 (2002).