Structural Reliability Analysis of Series Systems

Abstract

Reliability analysis of chain‐like series structural systems was performed for the special cases of lognormal stress and both Weibull and lognormal component strength. The goal was to relate component reliability to system reliability. This problem has application to establishment of design requirements, e.g. for fatigue avoidance in tethering components for marine structures or disks for turbine engines. When the events of failure of each member in a series system are assumed to be mutually independent, a simple expression for risk results. But component failure events are not independent, because of the presence of the same stress term in each event. Correction factors to be applied to the simple expression are derived for the stress and strength distributions considered. It is demonstrated, that the conservative assumption of independent component failure events can produce weight penalties of 10% or more. An example is provided which illustrates application of the results to establish a design requirement for a tendon of a tension leg platform.