State-of-the-art review of the reliability approach and methodology for the design of aerospace and ocean systems

In many weight-sensitive systems such as combat ships and aerospace craft, the common desire is to make the structural components lighter and lighter. Even for commercial ships, the structural scantlings have also been greatly reduced. Since the margin of safety of the structural design is much smaller, many engineers have used the reliability approach. The accuracy of such an approach depends on the accuracy of the methods for the prediction of the loading schedule expected in service, the prediction of structural responses, fatigue life, crack initiation, rate of crack propagation, and the reliability of the inspection methods to discover defects or cracks in time. Even though the trend is in favor of the reliability approach, some naval architects and designers remain concerned about its various uncertainties. This paper presents a state-of-the-art review of the methodologies and data required for the reliability approach. It is concluded that dependable solutions for all the probabilistic and deterministic problems of the reliability approach are available and that a simple procedure based on such an approach can be developed for ship structure design.