Systematic Design of Piezoelectric Modal Sensors/actuators

Piezoelectricity is the ability of some materials (notably crystals and certain ceramics) to generate an electric potential in response to applied mechanical stress and vice versa. Whenever this kind of materials produce an electric signal proportional to their deformation, it is said that they work as sensors, and conversely, when they convert electrical energy into mechanical one, as actuators. We are interested on understanding how a distributed transducer works ([4]), let us consider for instance a plate type-structure with two piezoelectric layers bonded to both top and bottom surfaces, respectively. When an electric field is applied to the piezoelectric lamina that is working as actuator, only the part of the lamina that is covered by electrode will be affected by the electric field, and consequently, only that region will undergo mechanical stresses. A similar effect can be found in the piezoelectric sensor. Rather than discrete transducers, distributed transducers are designed by shaping the surface electrode (sometimes also the polarization profile) of the piezoelectric layers, which let us determine both location and gain at the same time, reducing in that way the signal processing requirements.