Durability of composites in aircraft engine applications

Abstract

Aircraft engine components are subjected to high temperatures and complex stress states, thus requiring a much more rigorous assessment of durability. This chapter provides a brief introduction to durability assessment of polymer-matrix composites in gas turbine engine applications. The engine environment exposes the composite material to combined missions of hygrothermal exposure, mechanical loading, and fatigue. The complexity of the actual engine conditions is not easily duplicated in the laboratory and simplified simulated exposure missions are often used for durability characterization. Full-term durability testing to determine end-of-life properties is also not practical and accelerated testing and modeling is often considered as an alternative. Thus, a combined experimental and analytical approach is typically used to characterize durability of engine composites. A specific example of a woven composite material is described in this chapter to demonstrate how simple mechanics-based modeling can be used to study the evolution of the different damage mechanisms under fatigue and to predict fatigue life. Finally, the building block approach used to characterize the durability of engine components is discussed along with a specific example of its application.