MULTI-OBJECTIVE INITIAL PREVENTIVE MAINTENANCE SCHEDULING FOR LARGE ENGINEERING PLANTS

Abstract

Systems, sub systems and components of large engineering plants are grouped into Higher Modular Assemblies (HMA), all of which will need to be operational for the plant to be available. However, each HMA could have different intervals and durations for maintenance based on their different physical and functional characteristics resulting in narrow windows of plant operational periods. The problem of scheduling maintenance of large systems have been studied in literature in a limited way from this perspective and in practice, the management of the issue involves elements of subjectivity, sub-optimality and lack of adequate sensitivity analysis. The present paper views the initial scheduling of preventive maintenance as a constrained non linear multi-objective decision making problem. The objectives of reliability, cost and newly introduced criteria, non-concurrence of maintenance periods and maintenance start time factor are simultaneously optimized. The solution enables the decision maker to make a balanced choice of maintenance intervals which provide larger operational periods. The optimization problem is solved using an elitist GA and maintenance domain knowledge is effectively incorporated in its implementation.