Implementation of Reliability Design Theory on a Thin-Wall Vessel Structure

A component will not reliable unless it is designed with the required reliability. Since the Advisory Group on Reliability of Electronic Equipment (AGREE) published the “Reliability of Military Electronic Equipment” in 1957, engineering reliability has gradually become an engineering branch to serve engineering design. But implementation process of reliability in mechanical components design is slow. There are maybe two main reasons: (1) There is a lack of statistical descriptions of material mechanical properties; and (2) There is a lack of appropriate reliability design approaches for mechanical component reliability design, especially for a fatigue design under cyclic loads. A thin-wall vessel is a typical mechanical component under combined stresses. It is extremely hard to establish the limit state function for a thin-wall vessel structure under cyclic loads by using the P-S-N curve approach. For the fatigue design issue, the author proposes to use the probabilistic component fatigue strength index and fatigue damage index model, which has been proposed by the author, for establishing the limit state function for the thin-wall vessel structure under cyclic loads, and then determining its reliability under cyclic loads. This paper presents and explains how to establish the limit state functions of a thin-wall vessel structure under different typical static loads and cyclic loads. Two case study examples are provided for implementing the proposed approaches to conduct the reliability calculation of a thin-wall vessel structure under static load and a cyclic load.