furo

Actually you're the one who needs a basic course in metallurgy or materials science for that matter. If you had either, you'd clearly know that the yield strength and fatigue factors are inherent properties of the metal itself, and thus, cannot change. Just because an aircraft has 10 landings or 100,000 landings has no effect on the "yield strength stress ratio." The yield strength and ultimate tensile strength is purely a function of the metal itself. The funny thing here is you blabbering on about the aluminum airframe of the airplane, when this is clearly a corrosion issue associated with the rivet joints, not the aluminum chosen for the frame. Most likely it's a 2024 aluminum alloy. What probably occured, due to thermal expansion, was a plastic deformation in the rivet joints, which led to grain boundary growth in the critical areas of the rivet where creep has set in over time.source of info: I'm a materials engineer