ABSTRACT
In this chapter, the linear elastic fracture mechanics (LEFM) is introduced, the applicability of which lies in the K-similitude with fatigue crack growth rate data generated from standard coupons containing long cracks. However, load-shedding tests could cause crack closure and create the “threshold” phenomena. A transgranular fatigue crack growth rate model is developed based on the restricted slip reversal (RSR), which infers that fatigue threshold does not exist under mechanical fatigue conditions. An energy approach is also developed to correct for the crack closure-induced violation of K-similitude. Creep crack growth is dealt with stress-relaxation by dislocation climb-plus-glide and GBS in the crack-tip zones, which then lead to a creep crack growth rate model considering the effect of microstructure. Furthermore, creep-fatigue crack growth is also discussed in the context of ICFT.
