The primary cause of failure of metal structures is the growth of
a single crack to such a length that the load bearing ability of
the overall structure is compromised. For this reason, many models
for the growth of cracks have been developed.
Chapter 
deals with some of the previous methods
used. Attempts at modelling crack growth using the various
deterministic models, such as Paris-Erdogan and Forman equations
have had some success, when used to model the growth of long
cracks. Indeed, very many variations have been proposed to take
into account different features of the data. However, most
attempts to explicitly model crack growth have concentrated on
cracks which are microstructurally long. As seen, other methods
exist for modelling damage without explicit reference to the
underlying mechanism.
, M and d.