Fig. 5.
Number of cycles nF to contact-induced veneer failure from O and I cone cracks for epoxy-bonded glass/ceramic/polycarbonate trilayers, as a function of maximum contact load Pm, WC sphere r = 5. 0 mm. Failure data are shown for glass, alumina and zirconia cores. The lines through the O crack data are in accordance with Eq. (4), using N values from Table 1 and adjusting PO for each core material to give best fits. The lines through the I crack data are empirical fits to data. The dashed lines at the left are corresponding (material-independent) crack initiation functions (from [35]).