This book contains an elastic-plastic analysis of accumulate damage and fracture with practical applications with engineering materials and structure fatigue life estimations. Models as well as practical applications are presented, which makes the book interesting for both practitioners and theoretical researchers. Particular emphasis is laid on new approaches to the mixed-mode problem in fatigue and fracture, and especially to the fracture damage zone (FDZ) approach. The results of the demonstrated experimental and theoretical research lead to the presentation of different crack growth models, predicting the crack growth rate and, fatigue life of an initially angled crack under biaxial loads of arbitrary direction. Special attention is paid to the practical applications of the suggested models.