STATISTICAL-ANALYSIS OF THE FATIGUE LIFE DISTRIBUTION OF MONOLITHIC SILICON-NITRIDE

Cyclic fatigue testing of silicon nitride ceramics was performed at a frequency of f = 150 Hz and a stress ratio of R = 0.1 using a piezoele ctric bimorph fatigue device. Based on the method proposed by Fett and Munz, a fatigue crack growth diagram (K1-V diagram) was estimated fro m fatigue lifetime distribution data. A change in the slope of the K1- V diagram was observed. A statistical analysis for predicting the life time of ceramics exhibiting a transition in a K1-V diagram was devised on the basis of this observation. Analytical results obtained with th is method showed good agreement with experimental data.