MODELING OF PIEZOELECTRIC SENSOR FIDELITY

Ideal piezoelectric sensors should measure the response of a structure in a nonintrusive manner. The size of the sensor should be relatively small and its properties well matched to the structure. The voltage r esponse of a piezoelectric sensor embedded in a fluid loaded plate str ucture is modeled using a hybrid finite element approach. The structur e is excited by an obliquely incident acoustic signal. Finite element modeling is used far the structure and the fluid surrounding the trans ducer region, and a plane wave representation is invoked to match the displacement field on a mathematical boundary. On this boundary, conti nuity of field derivatives is enforced by using a penalty factor and t o further achieve transparency at the mathematical boundary, drilling degrees of freedom (d.o.f.) are introduced in the finite element repre sentation. Another novel feature in the FEM is the use of solid elemen ts for the acoustic fluid augmented by an irrotational constraint to r ender the fluid inviscid. Numerical results are presented for the sens or response on an immersed plate structure. The voltage excited in the piezoelectric sensor is studied as a function of sensor and host mate rial properties, size of sensor, and poling direction of the sensor wi th respect to the structure. The effect of multiple sensors on one ano ther is also studied. It is found that piezoelectric sensors can be no nintrusive and sensitive to the characteristics of the structure.