Piezoelectric Crystal vs Point Force Excitation of Beams and Plates

A point force equivalent to a pair of piezo actuators on a beam or plate has been ex pressed in terms of the ratio of applied moment to applied force which has been called an "equiva lence ratio". This ratio may be calculated on the basis of equal induced r.m.s. beam or plate displace ment amplitude or on the basis of equal power transmission at some axial location x downstream of the actuators. Over a large range of actuator sizes, locations and excitation frequencies, it has been shown that the power transmission equivalence ratio is a constant for any x, and the displacement equivalence ratio is independent of location x if x is in the far field of the source. Therefore, it is pos sible to simulate the far field vibration produced by a pair of piezoelectric crystals, attached in the same location on opposite surfaces of a rectangular section beam or plate, with a single applied force.