Numerical models based on finite element method have been employed to analyse the plasticity induced
crack closure phenomenon for a long time. These numerical analyses require the development of a plastic
wake. During the development of the plastic wake a transient behaviour can be observed on the numerical
results. Most of these previous analyses have been performed considering bi-dimensional models. The use
of three-dimensional models has been extended during last years. Nevertheless, the methodology
considered has been inherited from the bi-dimensional ones.
Optimising the numerical parameters involved on the development of the plastic wake is a key issue to keep
the computational cost under control, particularly when a three-dimensional analysis is considered. This
study presents a three-dimensional analysis of the influence of the crack growth scheme on fatigue crack
closure results. This three-dimensional analysis allows to study the influence of the number of loading
cycles not just on plane stress or plane strain conditions but all along the thickness.
In the present work, a CT aluminium specimen has been modelled three-dimensionally and several
calculations have been made in order to evaluate the influence of the number of loading cycles between
node releases and after releasing the last set of nodes on fatigue crack closure results. The numerical
accuracy is analysed in terms of crack closure and opening values and in terms of strain and stress fields.
