Effect of specimen geometry on ductile initiation CTODi using a direct method

This paper presents two approaches for use in defining the minimum size requirements for obtaining valid CTODi (crack tip opening displacement at ductile fracture initiation) measurements. The macroscopic approach uses the microcrack resistance curve (r-curve) to establish the validity of the CTODi criterion for ductile fracture initiation by reducing the specimen dimensions down to 1 mm for specimen thickness, 0.8 mm for the length of both …