Slow crack growth of brittle materials with exponential crack-velocity formulation?static fatigue

Abstract

The life prediction analysis based on an exponential crack-velocity formulation was made and examined using a variety of experimental data on advanced structural ceramics in constant stress (‘static fatigue’ or ‘stress rupture’) testing at ambient and elevated temperatures. The data fit to the relation between ln (time to failure) versus applied stress was be very reasonable for most of the materials studied, resulting in a similar degree of accuracy as compared with the power-law crack-velocity formulation. The major limitation in the exponential crack-velocity formulation, however, was that the inert strength of a material must be known priori to evaluate the important slow-crack-growth (SCG) parameter n, a drawback as compared with the conventional power-law crack-velocity formulation.