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Abstract
Second order nonlinear coefficients can be isolated by the measurement of second harmonic generation. A method is proposed to discriminate all four different coefficients: elastic, electroelastic, electrostrictive and dielectric. A Langevin tranducer, in which ceramic rings have been duplicated to behave as an electric biport, is used to measure them. The system is defined by two parameters: the electrical load connected to the second port, and the excitation frequency. The second harmonic generated current can be measured as a phasor at both ports, so at least two experiences must be done to determine all four coefficients. However, it is reasonable to do more than two experiences to minimize errors. The data treatment, deduced from a nonlinear equivalent circuit, and the measurement method are described.