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在地震模型实验中,需要指向性均匀、脉冲持续时间短的低频压电换能器。实验发现,具有匹配背衬的换能器发射脉冲的视周期总是比无背衬的长;向水中辐射的脉冲波形比向细棒中辐射的复杂。但没见过对这些现象的详细解释。 本文仅从基本压电万程和梅森等效电路出发,计算了长度模压电换能器的传递函数,并用数值方法计算了机电耦合系数k_(33)和复阻抗对长度模压电换能器脉冲波形的影响。结果表明具有匹配背衬的换能器k_(33)越大,其“单极”脉宽越宽;且复阻抗使脉冲波形变复杂。我们进行了复阻抗对脉冲波形影响的实验,计算和实验基本符合。在一定的近似条件下,可作为设计和使用脉冲压电换能器的参考。
In seismic model experiments, low-frequency piezoelectric transducers with uniform directivity and short pulse duration are needed. Experiments have shown that transducers with a matching backing always have a longer apparent period than a non-backed shot; the pulse shape radiated into the water is more complex than the radiation into the thin rod. But I have not seen a detailed explanation of these phenomena. In this paper, the transfer function of the length molded electric transducer is calculated based on the basic piezoelectric Wan Cheng and Mason equivalent circuits. The numerical simulation of the electromechanical coupling coefficient k_ (33) Effect of pulse waveform. The results show that the larger the k_ (33) of the transducer with the matched backing is, the wider the “unipolar” pulse width is; and the complex impedance makes the pulse waveform complex. We conducted a complex impedance experiment on the impact of the pulse waveform, calculated and experiment basically in line. Under certain approximate conditions, it can be used as reference for designing and using pulse piezoelectric transducers.