Flexible PZT-Polymer Laminated Composite Electromechanical Sensors and Actuators

摘要

Piezoelectric multilayer composite is widely used in piezoelectric devices which can offer a lot of benefits for applications of sensors and actuators. This kind of composite consists of several piezoelectric layers and several polymer layers connected in laminated composite structure in which both the piezoelectric and the polymer layers are continuous in two dimensions. In this thesis, lead zirconium titanate (PZT) film with thickness under 100um is chosen as the piezoelectric layers due to its relatively high piezoelectric charge constant, high electromechanical coupling effect and good mechanical flexibility. Five layers composite with two layers of PZT and three layers of polymer have been analyzed and developed for applications of two different structures of sensors and actuators including cantilever beam and doubly clamped beam. The static constitutive equations in matrix form for each structure under different excitations have been established analytically for theoretical analysis and characterization of the devices. Several dimensions of the polarizations of PZT element in doubly clamped beam are discussed for optimizing the electromechanical coupling performance. The dynamic admittance matrix which relates harmonic external excitations to their response parameters is also derived for cantilever beam. Several experiments have been conducted to partially verify the theoretical model. A cantilever beam actuator is fabricated and studied experimentally to verify the electromechanical coupling properties under harmonic external voltage under different frequencies. Two vibration sensors with proof masses with different structures are designed and tested as accelerometers.