Modal validation of a cantilever-plate bimorph actuator illustrating sensitivity to 3D characterisation

A dynamic finite element (FE) model of a small piezoelectric plate actuator with cantilever boundary conditions is validated experimentally using operating modes, as the scale of the device prevents conventional modal excitation. A general methodology is presented for assembly of 3D modal response of the plate surface from single-point laser vibrometer data, which is an economical alternative to the automated process provided by scanning vibrometers. 1D blocked force and 2D beam assumptions prove insufficient for validation due to modes both in the length and width of the device in operation. The model is validated in the audible frequency range encompassing 12 experimental operating modes. It is shown that when conducting validation using operating modes, the experimental results, simulated frequency response and FE eigenmodes must all be compared. Discrepancies between FE and experiment are identified and attributed to manufacturing imperfections above modelling errors.