A NEW APPROACH FOR SLOW CRACK-GROWTH MEASUREMENT

A new approach for the analysis of sub-critical crack growth measured by static and dynamic fatigues is proposed. This approach is based on the knowledge of the initial defect size distribution, which is mathem atically related to time to failure probability in the case of static fatigue or to the fracture stress probability in the case of dynamic f atigue. This method, which allows the determination of the sub-critica l crack growth parameters with a good accuracy with a minimum number o f specimens and under a single applied load, has been applied to mulli te and zirconia. In the case of the dynamic fatigue test, the sub-crit ical crack growth parameters can be obtained with a single loading rat e or with two close rates for more precision. Under these conditions, the parameters corresponding to the Wrst stage of the standard propaga tion law can be inferred, making the results relevant for lifetime pre diction.