Design Selection Decisions

The design selection problem in the RRM context considers long-term performance, and represents higher additional costs if unforeseen features that should have been included during the project design phase had to be implemented afterwards. Design decision involves multiple aspects and may be more critical depending on the kind of item, such as consumer appliances, industrial equipment or projects that have to consider safety aspects (airplanes or facilities). Reliability has an essential role for design selection although other aspects have to be considered such as maintainability and risk depending on the specific design problem. Therefore, a multidimensional approach is usually required. In this chapter, all these aspects are discussed in order to illustrate the importance of a broader perspective when facing design decision problems. The fundamental requirements are to consider reliability, maintainability and risk aspects so as to establish features in the design project, including the definition of material, redundancies, control systems and safety barriers. To illustrate these decisions, aspects such as reliability (e.g. MTBF), maintainability (e.g. MTTR), safety, cost, service life, efficiency, are discussed as criteria for these problems. Multi-attribute utility theory (MAUT) is applied in this chapter to illustrate how reliability, maintainability and risk aspects are included in an MCDM/A model for design selection incorporating states of nature. The decision regarding the selection of which features to include in a design project may be considered as an MCDM/A portfolio problem. Finally, an introductory view is given of how the redesign problem arises in the maintenance context with multicriteria approaches.