A novel evolutionary algorithmic solution approach for bilevel reliability-redundancy allocation problem

Abstract

Reliability-redundancy allocation problem (RRAP) is an optimization problem with objectives such as maximization of the system reliability and minimizations of cost, weight etc. It considers component reliability and the number of redundant components as decision variables. RRAP was mostly solved as a single level optimization problem. However, this problem has numerous variables and constraints. In this paper, we report a novel mixed-integer non-linear bilevel formulation for the RRAP of the series-parallel systems considering reliability, cost and weight as the main objectives. Then we show a novel way of solving the newly formulated bilevel RRAP using a latest bilevel optimization algorithm called BLEAQ (bilevel evolutionary algorithm based on quadratic approximations). Here, optimization is needed at two separate levels, where one problem is encircled within another problem. The inner problem is known as lower-level problem and the external problem is called upper-level problem. We demonstrate the working of the model considering a real-life example. For a thorough comparison, we also solve the problem using two existing bilevel evolutionary approaches to show the efficacy of our proposed solution approach.