A new approach to estimating the fatigue notch factor of Ti-6Al-4V components

Titanium alloy is used for airframe components and compressor blades application because of its high strength and fracture toughness at low temperatures and high strength and creep resistance at elevated temperature. This paper extends a recently developed probabilistic mesomechanics based model to notched titanium alloy components using simulation strategies that capture both the essence of notch root stress gradient and the complexity of realistic microstructures. The notch size effects and notch root and inelastic behavior are combined with probability distributions of microscale stress and small crack initiation to inform minimum life design methods. A new approach which can be applied using crystal plasticity finite element or closed form solution is also proposed as a more robust method for determining the fatigue notch factor than the existing classical methods. The fatigue notch factors predicted using the new probabilistic mesomechanics based model are in good agreements with experimental for notched titanium alloy specimens subjected to cyclic loads with various stress ratios.