Effect of Fatigue and Damage Tolerance Material Properties on the Efficiency of Aircraft Structures

Current aircraft structures have to meet the static, fatigue and damage tolerance (F&DT) criteria according to the actual FAA/EASA regulations. Furthermore, the structures consider common industry design standards, e.g. redundant structure, large damage capability, etc.The most efficient structure in fatigue sensitive areas will be achieved by combining materials with excellent fatigue, crack growth and fracture toughness properties, a good design practice and a reliable manufacturing process. Examples for materials with excellent F&DT properties are advanced Aluminum alloys and Fiber Metal Laminates, e.g. GLARE and CENTRAL.The overall result of the above described combination is a lightweight structure, which has an adequate fatigue life, a slow crack growth behavior not requiring penalizing in-service inspections and providing a large damage capability. Certainly this structure ensures compliance with the regulations and sufficient structural integrity during the operational life of the aircraft.The paper describes the above mentioned aspects with emphasis on the effect of the fatigue and damage tolerance properties on the allowable stresses and the weight of the structure. Three design solutions for a panel of the pressurized fuselage are presented.