Ductile fracture material characterization by J-R curves

Crack growth resistance J-R or delta-R curves are considered as the most promising candidates for the characterization of the fracture resistance of materials in the upper shelf toughness regime. Their use for the prediction of ductile tearing instability of components has already been successfully demonstrated. Mainly 3 methods to generate J-R curves are used and are described in detail: multiple specimen interrupted loading, potential drop, and single specimen partial unloading compliance. The advantages and deficiencies of each of these methods are discussed and results are compared. Additional methods for crack growth monitoring and using also crack tip opening displacement as a loading parameter are mentioned. Finally the parameters are shown which influence the crack growth resistance curves and deduced material values, such as temperature, specimen-geometry and size, side grooving, notch acuity or laoding rate; validity criteria are discussed. (IWM)