Hi,
The crack propogation analysis can be made using Finite elements using 2 models
1) Discrete Crack Model
2) Smeared Crack Model
In Discrete crack model u specify a crack propogation criterion in terms of starin energy release rates at the nodes of the elements. u presume that there is propogation of cracks all along the boundaries of elements between nodes.The main aspect from FE point of view is that how do u distribute ur stresses once a crack is formed.This again depends on the kind of materila behaviour.
In smeared crack model u assume that the failure is smeared over the entire element. This is advantageous to use when u have an adaptive FE -remeshing algorithm combined with the crack model. This gives good results for a suffciently refined mesh. The poropogation criterion being defined in terms of energy levels in the element.
Hope this helps
regds
