Sensing translational impedance by a Bimorph Impedance Transducer

This paper investigates the capability of a novel Bimorph Impedance Transducer (BIT) for measuring translational impedance of structures. A BIT, when supplied with ac power, exerts an excitation force to the structure under testing without a grounded base. During actuation, the translational vibrations of the structure at the point of excitation affect the input electrical impedance of the BIT as a result of the electromechanical interaction. The translational impedance of the structure can be sensed through measuring the electrical impedance of the actuator through the use of a transduction matrix which describes the system behavior of the transducer. This method employs only a stand alone, integrated transducer in measuring point translational impedance without the requirement of a load cell and motion sensor as compared to conventional methods thus the measurement system is greatly simplified. In this paper, the BIT is experimentally calibrated and then used to measure point translational impedance of a one-dimensional beam. Through comparing the results obtained by the BIT with the results from verification experiments using a shaker and an impedance head, it is concluded that the BIT is suitable for measuring translational impedance of structures.