Fatigue of Alumina Under Cyclic Torsion Loading

A study was conducted to investigate fatigue of alumina under cyclic torsion loading. Cylic torsion loading demonstrated that a biaxial stress state occurred under it, while the maximum shear stress remained the same as the maximum principal stress. All tests were carried out at room temperature and in ambient air using a torsional fatigue testing machine based on a commercial AC servo-actuator. An edge stress rate drmax/dt300MPa s-1 was used to determine the inert strength for the monotonic tests. The cyclic tests were carried out with a test frequency of 50 Hz under torsional torque control, while the final number of load cycle was selected as 107. Inert strength was evaluated using the Weibull theory, while the Weibull parameters were calculated using the maximum likelihood method.