Roughness of fracture surfaces
  We study the fracture surface of three dimensional samples through a model for quasi-static fractures known as Born Model. We find for the roughness exponent a value of 0.5 expected for ``small length scales'' in microfracturing experiments. Our simulations confirm that at small length scales the fracture can be considered as quasi-static. The isotropy of the roughness exponent on the crack surface is also shown. Finally, considering the crack front, we compute the roughness exponents for longitudinal and transverse fluctuations of the crack line (both 0.5). They result in agreement with experimental data, and supports the possible application of the model of line depinning in the case of long-range interactions. 
Andrea Parisi (1,2), Guido Caldarelli (1) and Luciano Pietronero (1)   ((1) INFM - Unita` di Roma 1 "La Sapienza", Roma (Ita...