In this paper analytic expressions are given to evaluate the reliability of systems consisting of components, connected in parallel or series, subject to probability box failure distributions. This development allows engineers to evaluate the structural reliability of systems without having to resort to Optimisation and Monte Carlo simulation, which are costly both in terms of the time spent programming and the time required for computation. The results obtained are also more accurate than the equivalent results calculated by simulation. We compare a worked example for a simple series system to the equivalent result from simulation
