The damage and fracture of materials are technologically of enormous interest
due to their economic and human cost. They cover a wide range of phenomena like
e.g. cracking of glass, aging of concrete, the failure of fiber networks in the
formation of paper and the breaking of a metal bar subject to an external load.
Failure of composite systems is of utmost importance in naval, aeronautics and
space industry. By the term composite, we refer to materials with heterogeneous
microscopic structures and also to assemblages of macroscopic elements forming
a super-structure. Chemical and nuclear plants suffer from cracking due to
corrosion either of chemical or radioactive origin, aided by thermal and/or
mechanical stress. Despite the large amount of experimental data and the
considerable effort that has been undertaken by material scientists, many
questions about fracture have not been answered yet. There is no comprehensive
understanding of rupture phenomena but only a partial classification in
restricted and relatively simple situations. This lack of fundamental
understanding is indeed reflected in the absence of reliable prediction methods
for rupture, based on a suitable monitoring of the stressed system. Not only is
there a lack of non-empirical understanding of the reliability of a system, but
also the empirical laws themselves have often limited value. The difficulties
stem from the complex interplay between heterogeneities and modes of damage and
the possible existence of a hierarchy of characteristic scales (static and
dynamic).
The paper presents a review of recent efforts from the statistical physics
community to address these points.Comment: Enlarged review and updated references, 21 pages with 2 figure
