Mode 2 stress intensity factor

HI

I am working on mixed mode fracture mechanics project . I was wondering what would be the appropiate mesh size to calculate the SIF of Mode 2 accurately

 i am using ansys to calculate the SIF's .. I need the size of the mesh in terms of the radius of the first ring  of quadratic elements .

 some specifications of my project that might be helpfull

Crack size = .1 (curvilinear crack)

width = 5

karan