Hybrid Structures for Improved Damage Tolerance of Unitized Structures

Recent developments of advanced hybrid metallic structural concepts have been extremely promising for durable light-weight and ultra-long fatigue life large transport aircraft.  The Alpha STAR team (Alcoa, SWRI, and Virginia Tech) proposes to extend the validated Fiber Metal Laminate (FML) high fidelity analytical capability from GLARE to CentrAl  FML concepts, as well as develop the necessary robust design optimization techniques.  Candidate ultra-long life approaches will be conceptualized and demonstrated on aerospace structural components. A building block verification strategy will be conducted. Observed test data will be compared with analytical predictions for unnotched/notched coupons under service loading conditions; static, fatigue crack initiation/propagation/residual strength, and thermal fatigue.  In Phase I, the team will validate the analytical tools with 5 stringer panel fuselage/lower wing test data under static and fatigue spectrum loadings. Our effort will lead to a robust design development and demonstration in Phase II of a unique FML stiffened panel concept to reduce weight and eliminate delamination.   This effort will expand the current GLARE applications from biaxial loading conditions, such as the Airbus-380 upper-fuselage, to CentrAl applications for a wider range of aircraft components, such as the lower wing cover. BENEFIT: Recent developments of advanced hybrid metallic structural concepts have been extremely promising for durable light-weight and ultra-long fatigue life large transport aircraft.  The Alpha STAR team (Alcoa, SWRI, and Virginia Tech) proposes to extend the validated Fiber Metal Laminate (FML) high fidelity analytical capability from GLARE to CentrAl  FML concepts, as well as develop the necessary robust design optimization techniques.  Candidate ultra-long life approaches will be conceptualized and demonstrated on aerospace structural components. A building block verification strategy will be conducted. Observed test data will be compared with analytical predictions for unnotched/notched coupons under service loading conditions; static, fatigue crack initiation/propagation/residual strength, and thermal fatigue.  In Phase I, the team will validate the analytical tools with 5 stringer panel fuselage/lower wing test data under static and fatigue spectrum loadings. Our effort will lead to a robust design development and demonstration in Phase II of a unique FML stiffened panel concept to reduce weight and eliminate delamination.   This effort will expand the current GLARE applications from biaxial loading conditions, such as the Airbus-380 upper-fuselage, to CentrAl applications for a wider range of aircraft components, such as the lower wing cover.)