Mechanics of Continua and Structures
Literature on variational fracture models
Variational fracture simulation of crack growth in multi-layer composites
Formulation notes of variational fracture with tension-compression split from Miehe et al. can be found here
The latex manuscript
The pdf file
The helical crack computational files in mathematica can be found here
The files include the elastic energy variation with the pitch for different geometric and material parameters. There is also a sample computational file with the theory and numerical implementation of helical FEA.