CYCLIC FATIGUE OF A MODEL FELDSPATHIC PORCELAIN

Objectives. This study was conducted to evaluate the fatigue parameter s of a model porcelain based on the Weinstein patent using cyclic fati gue and to compare the parametric values obtained from cyclic fatigue tests with those from dynamic fatigue tests previously reported by Fai rhurst et al. (1993). Methods. Cyclical biaxial flexure of 1 mm thick and 12 mm diameter disks was performed at 37 degrees C in distilled wa ter at a frequency of 4 Hz with constant stressing rates between a min imum and maximum stress. Three groups of samples (50, 40, 40) were tes ted with a maximum stress of 51, 47, and 43 MPa, respectively. The cra ck growth exponent, n, and the scaling constant sigma(fo) were derived from the regression constants obtained from a linear regression of th e logarithm of the median time to failure with the logarithm of the ma ximum stress. Results. No significant differences were found between t he cyclic fatigue parameters, n and sigma(fo) derived from the median time to failure and those obtained from dynamic fatigue data. Signific ance. Within the limits of error in this determination, the median cyc lic fatigue life can be estimated by the use of fatigue parameters obt ained from dynamic-fatigue testing.