Piezoelectric generation of extensional waves in an elastic bar by use of a power amplifier with constrained output current

Generation of extensional waves in a linearly elastic bar by means of a pair of attached piezoelectric actuators driven by a power amplifier with output current constraints is studied theoretically and experimentally. In addition to its current constraints, the amplifier is characterized by its DC voltage gain and 3 dB cut-off frequency. On the basis of 1D wave propagation, time-domain relations are established for the nonlinear dependence of the output voltage and current of the amplifier, and of the strain associated with the waves generated, on the input voltage. It is found that the amplifier model used allows prediction of the main features of this dependence. Nonlinear operation due to constrained output current may occur even at a low input voltage if the rate of change of this voltage is excessive. Consideration of this phenomenon is important in, e.g., control applications.