In the bridge indentation method, developed by earlier researchers to
produce precracks, the precracks in brittle bars can be conveniently p
roduced by the unstable pop-in of a Vickers indentation starter crack
using bridge-type loading. Because of the numerous test variables invo
lved, optimization and control of the precrack length can be difficult
. Based on experimental data, it was found that relative stiffness, pl
aten contact-surface friction and loading geometry can significantly a
ffect the precracking behaviour. The various effects were analysed usi
ng a parametric finite-element analysis. The predictions were compared
with experimental data and the behaviour was rationalized using simpl
e approximations for the stress distributions.