Fatigue and Damage Tolerance of Friction Stir Welded Joints for Aerospace Applications

Fatigue and Damage Tolerance of Friction Stir Welded Joints for Aerospace Applications

Lemmen, H.J.K.

Benedictus, R. (promotor)

Aerospace Engineering

Structural Integrity

2010-01-14

Friction stir welding is a young welding process with high potential to replace riveted joints in aerospace structures like the fuselage. Friction stir welding is a robust process and capable of welding high strength aluminum alloys. Therefore it can lead to both costs and weight savings. To substitute riveted joints by friction stir welded joints, it must be shown that the damage tolerance of the welded structure is similar as the structure with riveted joints. As the aerospace industry has over 50 years of experience with riveted joints, this is quit a challenge. The damage tolerance behavior of riveted joints is fully understood and the predictability is high. To get friction stir welded structures at the same level of readiness, the fatigue behavior of friction stir welded joints must be fully understood. The main focus of this research was to investigate the fatigue behavior, i.e. fatigue initiation and fatigue crack growth, of friction stir welded aerospace aluminum in order to understand which parameters play a role. This knowledge enables to build prediction models which can be used to evaluate the damage tolerance of a welded structure. Consequently, it is possible to come up with design rules for a damage tolerant friction stir welded fuselage structure.

friction stir welding
damage tolerance
fatigue initiation
fatigue crack growth
residual stress
yield strenght profile

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doctoral thesis

(c) 2010 Lemmen, H.J.K.