applied fracture mechanics

328Applied Fracture Mechanics5. Based on crack growth simulations in the first and the second fractured blades, the totalfatigue crack growth time was calculated as only about one hour, which is within the 11hours of actual operating period following the last overhaul, ending with the failure offan blades.NomenclatureA cross-sectional area, m 2aa0ca/cFHKICKtKbmNQrtgσtσbΔσcrack depth, minitial crack depth, mlength for corner cracks and half-length for surface crackscrack aspect ratioboundary correction factor on stress intensity factor for remote tensionbending multiplier on stress intensity factor for remote bendingcritical stress intensity factor, MPa mstress intensity factor due to tension, MPa mstress intensity factor due to bending, MPa mmass of blade, kgrotational speed, revolutions per secondcrack shape factordistance from center of rotation, mfatigue crack growth time, hourstensile stress, MPabending stress, MPastress range, MPa K ththreshold stress intensity factor range, MPa m K stress intensity factor range, MPa mdadNCncrack growth rate , m.cycle -1empirical material constantempirical material constantAuthor detailsMahmood Sameezadeh and Hassan FarhangiUniversity of Tehran, College of Engineering, Iran