压电换能器的声非线性

通过对输入回路中的电流进行谐波分析，得到了在不同输入信号电压下的非线性信号强度，并以此来表征压电换能器本身振动非线性的大小。

ACOUSTIC NONLINEARITY IN PIEZOELECTRIC TRANSDUCERS

In an acoustic nonlinearity measurement system, the measurement results may be seriously effected by the nonlinearity originated from piezoelectric transducer itself, therefore it is obviously important to evaluate the nonlinearity of the transducer under resonance condition. This paper investigates the vibration nonlinearity of LiNbO 3 crystal wafer which is commonly used as ultrasonic transducer. The nonlinear signal excited by transducer itself at different input voltage was characterized using the measurement of the input circuit current and the analysis of its second harmonic at the resonance frequency. In experiment, the nonlinearity of LiNbO 3 crystal wafer working in the cases of free resonator and with acoustic load was investigated and compared with Langevin transducer. The results show that the vibration nonlinearity of LiNbO 3 transducer is much smaller than that of Langevin transducer, and could be ignored in the normal measurement system. The theoretical analysis of LiNbO 3 free resonator is also shown in this paper, which is in good agreement with the experimental results.