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Two approaches are developed for geometrical modeling of crack growthtrajectories for the inclined through thickness central cracks and the part-throughsurface flaw respectively. The principal feature of such modeling is the determination ofcrack growth direction and the definition of crack length increment in this direction.The damage process zone size concept is employed for calculations of mixed-modecrack growth trajectories and surface flaw shape and positions. Crack front behaviorfor a straight-fronted edge crack in an elastic bar of circular cross-section is studiedthrough experiments and computations under axial tension loading. The elaboratedtheoretical model is applied for fatigue crack shape simulation of part-through cracksin a hollow thick- and thin-walled cylinders under different biaxial loading conditions.Suggested approach of crack paths modeling is used for an analysis and prevention ofoperation failures of existing in-service aircraft gas-turbine engine rotatingcomponents.