Efficient calculation of stress intensity factors using virtual crack extension technique

This paper presents a finite element analysis of calculating stress intensity factors for Mode I, Mode II and mixed-mode planar fracture problems using the virtual crack extension technique. Results show that whilst the accuracy of the predicted stress intensity factors may be significantly improved upon by adding a small rosette around the crack tip, this improvement is strongly dependent on the size of the rosette. A new procedure is devised to estimate the stress intensity factors by using two calculations with different rosette sizes for a given mesh. The new method provides robust estimating ability, even for very coarse meshes.