NEW APPROACH FOR THE JOINT OPTIMIZATION OF THE DESIGN AND MAINTENANCE OF MULTI-COMPONENT SYSTEMS BY INTEGRATION OF LIFE CYCLE COSTS

This work presents a methodology for simultaneous design and maintenance optimization which objective's the minimization of the life cycle cost. This methodology helps designers to optimize the design of complex industrial systems (multi-component systems) based on the minimization of the life cycle cost (LCC). The research contribution comes from integrating two optimization tasks which traditionally are carried out in separate ways. In fact, during the design phase, the system architecture is usually optimized by neglecting maintenance expenses. While during the operational phase the system architecture is already finalized and maintenance optimization approaches allow only determining a minimum maintenance cost. In this work, design optimization refers to the optimization of reliability and maintainability characteristics. There are two approaches for optimizing reliability. The first one considers component reliability as a decision variable, and its cost is considered as a predetermined increasing function of component reliability. The second approach aspires to determine the type and number of redundant components of each subsystem. On top of that, there are two approaches for maintainability. The first one considers component accessibility as a decision variable, and its cost is considered as a predetermined increasing function of component accessibility. While, the second approach focuses more on the monitoring architecture. In addition, the maintenance optimization is able to optimally and automatically select what maintenance actions are applied, when they are applied, and to which structural components they are applied, so that the system can perform these missions with the required confidence level.