Characterisation of crack tip fields—CCTF5

Single parameter characterisation of the crack/notch tip field using fracture mechanics parameters like K, J, or CTOD has been extremely powerful in advancing predictive technologies for critical or subcritical crack growth. It has also become clear over the last decades that single parameter approaches have limitations particularly in dealing with crack growth phenomena arising from crack tip shielding, often resulting from the plastic enclave surrounding a crack. Influences of this enclave on the crack tip stress field ahead of the crack are maximised during cyclic loading. In the case of a parameter like the stress intensity factor that characterises the crack tip field via an elastic approximation, it is not surprising that any set of plasticity-induced circumstances that perturb the size of the plastic enclave and its associated strain field leads to predictive difficulties. Over the last 40 years, notable areas of activity related to such difficulties include short cracks, plasticity-induced closure, variable amplitude, multiaxial loading, and notch effects.