Damage Tolerance Demonstration of Flange Joint for Aircraft Engine Composite Fan Case

Abstract

Fan Case of aircraft turbo fan engines is located in the front end of an engine, and surrounds a periphery of fan blades. When a fan blade fails for some reasons, which is called fan blade out event, fan case needs to prevent high energy debris from penetrating through it. When a blade out event occurs, fan case is subjected to a very large load, which is called FBO load. FBO load is followed by repeated unbalance load due to wind milling while the aircraft returns to an airport after the event. Therefore fan case needs to endure not only the FBO load but also repeated unbalance load after the event. This is called “Fly home capability”. Also it is necessary to confirm that defects, such as delamination caused during manufacturing process, do not have the detrimental effects on the structure integrity requirements. In this paper, damage tolerance capability of a flange joint of a composite fan case is discussed. Subcomponent tests of flange joints are conducted. Artificial delaminations, which can be detected by non-destructive inspection, are introduced to the test specimens. Test results show that the detectable delamination does not have detrimental effects on durability, ultimate load capability, or fly home capability.