Analysis of structures under uncertainties

Abstract

Theories of uncertainty are applied to a large range of fields, and they have a special interest on engineering, because of safety and risk concerns related to human lives. This concern is very high on aerospace applications, where safety is truly the most critical requirement. The most common approach to deal with uncertainties due to lack of knowledge and inherent variability on aerospace structures is through the application of safety factors, which are design margins against failure. Safety factors are applied on all scales from simple components to more complex systems. Within this paper, inherent variabilities are expressed through statistical distributions, which is an alternative approach to traditional safety factors. Structures are interpreted as systems whose reliability level should be assessed. The range of application of these theories is large, and two examples related to aircraft structures are discussed in this work. In first example, the reliability analysis is applied to estimate the inspection interval for a typical structural aluminum joint, and in the second one, the reliability a composite structure under progressive damage until collapse is evaluated. The results obtained are presented and discussed.