On Probabilistic Design

Abstract

The probabilistic approach to design is developed and contrasted with the conventional safety factor approach. A careful interpretation of random variable design inputs is given, leading to a statistical extreme-value model of loads. In addition to the “reliability” concept, the concept of “mission length” is explicitly introduced to the design process. A simple design problem, involving random variable loads and constant material properties, is solved and illustrated. Possible extensions of this design problem, and their likely difficulties, are indicated.