FRETTING FATIGUE-STRENGTH ANALYSIS OF TI-6AL-4V IN AIR

Axial fatigue loading was applied at frequencies of 20 Hz and 0.5 Hz in a laboratory environment. The reduction in fatigue strength due to the fretting damage depended on the contact pressure, p. When the value of p is about 20 MPa, the fatigue life exhibited a minimum. The fretting fatigue crack initiated at the center of the fretted surface. Many microcracks existed prior to the main crack initiation. However, when the value of p is more than 30 MPa, the fretting fatigue crack initiated at the edge of the fretted surface. Few microcracks existed prior to main crack initiation. Fretting fatigue cycles of more than 90% of the total life in the interrupted fretting fatigue test are required in order to continue crack propagation after the removal of the fretting pad used in the tests.