Component Lifing Decisions and Maintenance Strategies in the Context of Aeroengine Product-Service Systems Design

Static structural engine components are typically designed for full lifetime operation. Efforts to reduce weight in order to improve performance result in structural designs associated with higher lifing uncertainty: Maintaining reliability levels may necessitate expensive manufacturing and maintenance solutions. In practice, repair techniques for such structures are available; however, they are not planned for during the design process. The objective of the research presented in this paper is to model and optimize component lifecycle costs with respect to lifing decisions, demonstrated by means of an aeroengine component design example. Both technical (failure) and legislative (certification) implications are considered. The impact of maintenance strategies (repair and/or replace) on lifing design decisions is quantified. It is shown that, under different conditions, it may not be prudent to design for full life but rather accept shorter life and then repair or replace the component. This is especially evident if volumetric effects on low cycle fatigue life are taken into account. It is possible that failure rates based on legacy engines do not translate necessarily to weight-optimized components. Such an analysis can play a significant supporting role in engine component design in a product-service system context.