Experimental validation of a modal transducer for an orthotropic rectangular plate

Abstract

A general Selective Modal Transducer (SMT) design methodology previously derived by the authors for piezolaminated anisotropic plate systems is validated through experimental test on a cantilevered orthotropic composite piezolaminated plate. Fundamental aspects of the SMT theory are first reviewed. The SMT theory is then extended to provide the means to predict the modal character of multilayered piezolaminated transducers embedded in an anisotropic plate in which the active subelements are both bi-directional and spatially varying. An experimental procedure is described involving a ten-layered orthotropic plate constructed from four graphite-epoxy layers sandwiched between six piezoelectrically active PVDF sublaminae. Three PVDF sublaminae stacked on one face are combined electrically to provide a single sensed measurement, while the three remaining PVDF sublaminae stacked on the opposing face are combined to provide single channel actuation. Lead compensation is employed to provide active control. Open and closed loop frequency and transient response data are then analyzed in order to determine both the natural frequencies and damping coefficients of the first four vibrational modes. Significant active vibration attenuation is observed. A numerical simulation directly based on an SMT-derived transducer model is developed, and simulation results are then compared to the actual system behavior. The theoretically based numerical results are seen to closely resemble the measured response to within an expected range of accuracy, thus validating the transducer theoretical model predicted by the SMT theory.