PIEZOELECTRIC FIBER COMPOSITES WITH INTERDIGITATED ELECTRODES

Piezoelectric Fiber Composites were previously introduced as an altern ative to monolithic piezoceramic wafers for structural actuation appli cations. This manuscript. was an investigation into the improvement of piezoelectric fiber composite performance through a nonconventional e lectroding scheme. Two microelectromechanical models were developed th at predict the composite properties. These models were used to examine the trends of composite properties versus fiber volume fraction for v arious constituent materials. Several etched electrode PZT fiber compo sites, with fiber volume fractions ranging from 7% to 58%, were manufa ctured and tested. Experimental measurements showed excellent agreemen t with both the trends and magnitude of model predicted values. The ma ximum fiber volume fraction composites demonstrated a capacitance (eps ilon(33)(T)/epsilon(0)) Of 550, piezoelectric free strain constants (d (33) and d(31)) Of 150 pm/V and -70 pm/V, and piezoelectric clamped st ress (e(33)) of 5 C/m(2), showing a substantial improvement over previ ous piezoelectric fiber composites with uniform electrodes. Maximum st rain values of 1700 ppm were measured, indicating higher in-plane actu ation than monolithic piezoceramics.