Piezoelectric Fiber Composites with Interdigitated Electrodes

Piezoelectric Fiber Composites were previously introduced as an alternative to monolithic piezoceramic wafers for structural actuation applications. This manuscript was an investigation into the improvement of piezoelectric fiber composite performance through a nonconventional electroding scheme. Two microelectromechanical models were developed that predict the composite properties. These models were used to examine the trends of composite properties versus fiber volume fraction for various constituent materials. Several etched electrode PZT fiber composites, with fiber volume fractions ranging from 7% to 58%, were manufactured and tested. Experimental measurements showed excellent agreement with both the trends and magnitude of model predicted values. The maximum fiber volume fraction composites demonstrated a capacitance (E3 /Eo) of 550, piezoelectric free strain constants (d33 and d31) of 150 pm/V and-70 pm/V, and piezoelectric clamped stress (e33) of 5 C/m2, showing a substantial improvement over previous piezoelectric fiber composites with uniform electrodes. Maximum strain values of 1700 ppm were measured, indicating higher in-plane actuation than monolithic piezoceramics.