Pages: 43 Published: Jan 1999
THE LIFE OF STRUCTURAL components that contain cracks or that develop cracks early in their lives may be governed by the rate of subcritical crack propagation. Proof-testing or nondestructive testing procedures or both may provide information regarding the relative size and distribution of possible pre-existing cracks prior to service. However, these inspection procedures are usually used to establish upper limits on the size of undetectable discontinuities, rather than actual crack size. These upper limits are determined by the maximum resolution of the inspection procedure. Thus, to establish the minimum fatigue life of structural components, it is reasonable to assume that the component contains the largest discontinuity that cannot be detected by the inspection method. The useful life of these structural components is determined by the fatigue-crack-growth behavior of the material. Therefore, to predict the minimum fatigue life of structural components and to establish safe inspection intervals, an understanding of the rate of fatigue-crack propagation is required. The most successful approach to the study of fatigue crack propagation is based on fracture-mechanics concepts.
Paper ID: MNL10331M