Numerical and experimental study of thinned-bulk piezoelectric harvesters
Résumé
Bulk piezoelectric cantilever beams are mostly assembled under serial bimorph topologies where the piezoelectric material is laminated around an inner shim material. The two PZT layers exhibit an individual thickness ranging from few tens to hundreds of micrometers according to the targeted application and its miniaturization requests. Designing such devices becomes a challenge and one needs FEM (finite element model) to properly define material thicknesses and overall piezoelectric energy harvester geometries. Unfortunately, bulk piezoelectric material are characterized using thicker samples which provide results slightly different from the actual characteristics of thinned-bulk piezoelectric materials. Previous works have addressed an approach to study the thin piezoelectric material layer relying on the electrical admittance analysis. Then, the effective coefficients of thinned-bulk piezoelectric material are identified and entered in a 3D FEM of the PZT layer. The electrical admittance is calculated, showing a good agreement with the experimental measurements.