R-curve for a lead zirconate titanate ceramic obtained from tensile strength tests with Knoop-damaged specimens

A procedure was used that made it possible to determine the R-curve for piezoelectric ceramics from tensile strength tests conducted with Knoop-damaged specimens. The resulting crack-tip toughness K-10 was 0.6 MPa .m(1/2), and the R-curve starting from this value increased to 1.4 MPa .m(1/2) within a 0.7 mm crack extension.