Design for flexibility: Evaluating the option to extend service life in preliminary structural design

In this paper, a new type of real options analysis is used to evaluate the worth of an option to extend the service life (ESL options) of an aluminum structure from twenty to twenty-five years. It is an early application of prospect theory-based real options analysis (PB-ROA) in naval design. PB-ROA abstracts the principles of real options analysis to suit naval design applications where the assets do not generate cash flows, and therefor one cannot define value in monetary terms. Instead, the example in this paper defines the utility of a structural design based on three components: structural availability, cargo capacity, and producibility. The utility is contingent on risk factors like the time to crack initiation of a welding detail which is included using stochastic fatigue analysis. From an entire Pareto front of optimal structural designs, the options analysis exposes a partition in the design space which could be valuable in a design setting. The partitioning reveals the conditions in which certain candidate designs maximize the present value of future flexibility. Ultimately, this paper demonstrates a new approach to valuing flexibility in preliminary structural design that may generate useful insight for early stage decision makers.