According to aeroengine structure integrity program

fracture critical components must be analysed with damage tolerance concept.Due to crack propagation produced by material defects

working defects or fatigue defects can make structure fracture.Therefore

the sufficient damage tolerance should be maintained.It is realized by selecting material correctly

controlling stress level

using the anti fracture structures and reliable inspection.In this paper

the structural reliability concept is applied to studying optimization of materials for maximum reliability under certain stress levels and crack sizes

to investigating variation influences of material strength and stress level on structure reliability.