ABSTRACT
52 Chapter 3 presents the probabilistic concepts and methods related to fatigue crack damage detection. An overview of time-dependent crack propagation is provided to predict the crack size at a specific time and the time for the crack to reach a predefined size. The relation between the probability of fatigue crack damage detection and crack size is presented. The probability of damage detection for multiple inspections is formulated. Uncertainties associated with the damage occurrence time and damage detection are considered in the formulation of the expected damage detection delay. Furthermore, using the damage detection delay and a time-based safety margin, the damage detection time-based probability of failure is formulated. The effects of inspection times on the probability of fatigue damage detection, damage detection delay and damage detection time-based probability of failure are investigated. These concepts and approaches are presented in this chapter, including the formulation of damage detection-based optimization objectives, and can be used for probabilistic optimum inspection and monitoring planning in Chapter 4, 5, 6 and 7.
