Analysis and Experimental Evaluation of a New Planar Piezoelectric Accelerometer

In this paper, the behavior of a new planar piezoelectric accelerometer is investigated, both theoretically and experimentally. The proposed accelerometer is composed of a piezoceramic ring filled, in its inner space, with a seismic mass. The theoretical analysis has been carried out by using a matrix model of the radial symmetric modes of the thin piezoceramic ring, recently proposed by the authors. The numerical results obtained for the empty ring show that, the response being constant, the bandwidth increases when the annulus radius increases. On the contrary, by inserting a high-density and stiffness seismic mass, both the response and the bandwidth increase by increasing the percent quantity of the seismic mass. The measurements of admittance and sensitivity, carried out on a test specimen, validate the computed results and demonstrate that the accelerometer is planar, i.e., it is able to detect the mechanical excitation from any radial direction, independently of the azimuthal angle. Finally, an accelerometer composed by two of such elements, stacked and connected in parallel, has been realized. It has shown a sensitivity quite flat and of appreciable value in a very wide frequency range.