Mechanics of Crack Tip Deformation and Extension by Fatigue

This paper surveys the continuum mechanics of deformation near cracks and its application to propagation by fatigue loadings. Results of various elastic-plastic models are summarized and compared in relation to hardening behavior, size effects, and large scale plastic yielding. The role of the elastic stress intensity factor variations in governing local plastic flow, and thus crack growth rates, is emphasized for the common high-cycle low-stress fatigue situations. General features of crack propagation are discussed, and theories are examined which seek to relate continuum analyses to separation mechanisms.