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 response of a piezoelectric sensor embedded in a fluid loaded plate structure is modeled using a hybrid finite element approach. The structure is excited by an obliquely incident acoustic signal. Finite element modeling is used for the structure and the fluid surrounding the transducer region, and a plane wave representation is invoked to match the displacement field on a mathematical boundary. On this boundary, continuity of field derivatives is enforced by using a penalty factor and to further achieve transparency at the mathematical boundary, drilling degrees of freedom (d.o.f.) are introduced in the finite element representation. Another novel feature in the FEM is the use of solid elements for the acoustic fluid augmented by an irrotational constraint to render the fluid inviscid. Numerical results are presented for the sensor response on an immersed plate structure. The voltage excited in the piezoelectric sensor is studied as a function of sensor and host material properties, size of sensor, and poling direction of the sensor with respect to the structure. The effect of multiple sensors on one another is also studied. It is found that piezoelectric sensors can be nonintrusive and sensitive to the characteristics of the structure.