Theoretical and Experimental Studies to Develop a Piezoelectric Shear Stress Interface Gage

Theoretical developments to analyze the impact response of rotated-cut piezoelectric gages are presented. Requirements for an ideal shear gage are outlined, and a theoretical framework to incorporate more realistic response is developed. Impact experiments to determine the current output from 163 deg - and 165.5 deg-rotated Y-cut shorted LiNb03 gages have been performed. The experimental results show that the 163 Y-cut orientation is more sensitive to shear than compression and has no cross-axis shear sensitivity. As expected, the compression response is higher for the 165.5 Y-cut orientation. Experimental results suggest the importance of accounting for the effects of anisotropy, impact tilt, and minor variations in the orientations of the crystals. In detailed comparisons of theory and experiment, these effects were included. These comparisons showed that for shear loading the agreement between theory and experiment is good (within 3 percent); for compression loading the agreement is only to within 10 to 15 percent. An accurate determination of the piezoelectric constant e sub 22 and the elastic constant c sub 12 superscript D, with precise measurements of the orientation of crystals to be used in the experiments, is needed before drawing further conclusions about the causes for the disagreement between theory and experiment. Specific recommendations for future theoretical and experimental efforts are suggested.