| Popis: |
The dynamic strain amplitude of sapphire whisker reinforced and nonwhisker reinforced types I, II, and III piezoelectric ceramics was measured as a function of increasing electric field until fracture occurred. The 1‐in.‐diam by 0.2‐in.‐thick disk specimens were poled in their [33] direction and excited at their planar resonance. The direct measurement of radial displacement amplitude allows accurate assessment of the nonlinear behavior of piezoelectric and elastic constants from low to very high excitation fields. Test results show that previous determinations of peak dynamic tensile strengths, based on calculations which assume linear d constants, can result in large error. In addition, the investigations show the whisker‐reinforced ceramics exhibit linearity and excellent performance to excitation levels unattainable by their nonwhisker‐reinforced counterparts. [This work sponsored in part by ONR Code 468.] |
