ABSTRACT
This chapter gives a systematic treatment of Zener-Stroh-Koehler (ZSK) and Bilby-Cottrell-Swinden (BCS) dislocation pile ups leading to crack nucleation within anisotropic materials, using the continuously distributed dislocation theory (CDDT). Generally, there are couplings between Mode I, II and III crack formation in a crystalline solid. For modeling short crack behavior, the bounded and unbounded solutions are obtained for BCS cracks, corresponding to the extended slip band (ESB) and blocked slip band (BSB) models, and furthermore the solution for the propagated slip band (PSB) model is also derived. The anisotropic formulation is used to deal with the short crack growth phenomena from in-situ observation on a Ni-base superalloy. It is pointed out that treatment of short crack behavior in terms of long-crack fracture mechanics parameters is not appropriate.
