
Modelling fracture processes in orthopaedic implants 347
In practice, all of these models can occur simultaneously.
For load type I, α is 1, which gives the following formula:
[11.16]
Quasi-brittle material fracture resistance in terms of force (just like the crit-
ical parameter, G
c
, in terms of energy) is determined by the critical stress
intensity factor, K
c
, called fracture toughness. After reaching the value of K
c
,
catastrophic fracture development begins.
Between the factors K
c
and G
c
, the following relationships exist:
for plane state of stress: •
[11.17]
for plane ...