Fatigue crack closure has been studied by means of the finite element method for a long time. Most work
has been performed considering bi-dimensional models where the numerical methodology has been
developed. A great number of bi-dimensional studies analyses different numerical parameters and
optimise them.
Three-dimensional models have extended lately. Nevertheless, the methodology employed was taken
from the one developed for bi-dimensional cases. The current computational capabilities allow a
comprehensive three-dimensional study of the influence of the different modelling parameters in a similar
way to those studies carried out with bi-dimensional models.
In particular, one of the key issues is related to the element size, which has a huge influence on crack
opening and closure values. In the present work, a CT aluminium specimen has been modelled threedimensionally
and several calculations have been made in order to evaluate the influence of the mesh size
around the crack front. The numerical accuracy is analysed in terms of crack closure and opening values.
Classical bi-dimensional recommendations are updated. A similar linear relationship has been identified
and a minimum mesh recommendation of 60 divisions of the Dugdale’s plastic zone size is made.
