Tradeoff of Structural Weight and Inspection Cost in Reliability Based Optimization using Multiple Inspection Types

This paper develops a methodology for cost optimal reliability based structural design and inspection planning of aircraft structures subjected to fatigue damage growth. The methodology is based on the application of methods of structural reliability analysis. An optimization problem is formulated to minimize expected lifetime cost while maintaining the minimum acceptable reliability level. The effect of structural design and inspection schedule on operational cost and reliability is explored. Also, the paper explores the possibility of trading cost due to additional structural weight with inspection cost to obtain minimum operational cost. The optimization parameters are the inspection times and types and the structural thickness. The important outcome of this methodology is consistent evaluation of consequence of different inspection and handling of uncertainty.