Fatigue evaluation of TC17 titanium alloy shaft with surface scratch based on FEA and fracture mechanics

Abstract

With the development of advanced mechanical equipment, more attention should be paid to the fatigue evaluation of the critical components affect by surface scratch, like the TC17 titanium alloy shaft. The designed fatigue test is carried out to reveal the negative effect of surface scratch on fatigue failure, and the fatigue limit model for TC17 titanium alloy with surface scratch is proposed based on the Murakami equation. Then, FEA with different surface scratches for TC17 titanium alloy shaft is carried out, an empirical formula is proposed to express the relationship between the stress and surface scratch. In addition, the unknown parameter related to TC17 and the specific stress intensity factor model is identified, to estimate the critical surface scratch of TC17 titanium alloy shaft. With the comprehensive application of the classic theory and new proposed models, a new fatigue life evaluation model of TC17 titanium alloy shaft with surface scratch is developed and verified, whcih is novel and essential to the maintenance of the damaged TC17 titanium alloy shaft.