Time Dependent and Cyclic Dependent Effect of Alumina Ceramics under Cyclic Fatigue Condition

The mechanical behavior of smooth specimens is different from that of notched ones and is very important for practical use. From this point of view, cyclic fatigue behavior of smooth specimens of alumina ceramics was investigated. We carried out the cyclic fatigue test ranging from 10-3Hz to 6×102Hz. We used the resonance vibration method for high frequencies. We estimated the cyclic-dependent region and time-dependent region of fatigue life for alumina ceramics under the cyclic fatigue conditions. This estimation will be practically useful for predicting the fatigue life. The cyclic fatigue life is controlled by the cyclic-dependent mechanism for higher frequency region and by the time-dependent mechanism for lower frequency region. However, the transition area from time-dependent to cyclic-dependent mechanisms is revealed. This transition area is affected by applied gross stress level.