Failure analysis of Ti6Al4V titanium alloy under fatigue loading: An experimental and numerical study

A correct assessment of the fatigue strength of Ti6Al4V titanium alloy is paramount for ensuring component integrity and durability during service life in many industries, such as aerospace, naval, and biomedical. This study investigates the failure of smooth and notched specimens under axial fatigue loading, at a stress ratio R=0. The stress concentrations at the notches are evaluated with the finite element method. Experimental results obtained with a step loading procedure reveal significant differences in fatigue strength between smooth and notched specimens. The fatigue strength of notched specimens is found to be much lower than that of smooth ones mainly due to stress concentration effects. The role of stress concentrators in premature cracking is confirmed by the observation of the fracture surfaces of the tested specimens. The Goodman failure criterion is used to describe the observed fatigue behavior. The discrepancies found between the experimental results and those obtained using the Goodman criterion can be considered acceptable. This work contributes to a better understanding of the failure behavior of Ti6Al4V under fatigue, which is essential for the design of reliable components subjected to dynamic loading.