Study of probabilistic approach for structural health assessment of aerospace structures

Current practical approaches used in structural health assessment programs of aerospace structures involve performing a fracture mechanics analysis to verify the safe life of structural components. The analysis typically makes several conservative assumptions implemented by NASA fracture control standard practices for critical structural components. This well-established paradigm for fracture control follows a deterministic approach and, in some cases, the calculations may produce overly conservative remaining life estimates. This thesis describes the results of a study to approach the health assessment challenge of several critical components using probabilistic methods. The probabilistic analysis takes the current deterministic model and identifies variables that may have a significant level of uncertainty associated to them. The uncertainty in selected geometrical, material, and load variables is modeled by searching published and unpublished papers and reports. The Monte Carlo simulation method was used to calculate probabilities that the specified life is reached and to identify variables whose uncertainty influence the predicted life of the structural components the most. This thesis presents results of a proposed health assessment approach applied to several critical components of an aerospace structure consisting of different crack models and materials