Abstract
A statistical approach for risk-based maintenance of damage tolerant components is presented. Damage risk is defined here as the repair cost times damage probability that is defined as the probability of cycles to emerging certain amount of damage. The thermomechanical fatigue cracking of gas turbine nozzles was studied statistically as the typical example. Probabilities of cycles to critical crack size (failure probability) and that of cycles to total length of cracks (damage probability) were calculated using plant inspection data and experimental results of low cycle fatigue. The life cycle costs of damage tolerant components are optimized through the sum of the failure risk and the damage risk.
