压电瞬态响应在换能器声功率测量中的应用

Application of piezoelectric transient response in transducer acoustic power measurement

探索一种简便的聚焦超声功率测量方法,利用压电陶瓷片直接接收超声信号,通过机电类比得到压电瞬态响应由压电片在声波作用力下引起受迫振动产生的电压响应与固有振动产生的高频衰减响应叠加而成,分析输出压电信号与换能器声功率之间的换算关系。对输出压电信号进行二次包络提取,获得表征声功率变化的电压幅度曲线,分别找出不同换能器驱动电压下包络曲线的最大峰值电压,将其平方值与声功率计所测声功率进行线性拟合,并对理论关系式中的比例系数进行标定。实验结果所得线性拟合度较高,且标定后所得声功率与声功率计所测值相对误差低于8.7%,证明了通过压电瞬态响应测量换能器声功率具有可行性。

To explore a more convenient measurement of focused ultrasound power, piezoelectric ceramic plate was used to receive ultrasonic signal directly. Due to an acoustic force acting on the surface of piezoelectric ceramic plate,by means of electromechanical analogy, the transient response was obtained, which was composed of voltage response caused by forced vibration and high frequency attenuation response caused by natural vibration,then the conversion relationship between output signal of piezoelectric ceramic plate and transducer sound power was analyzed. The envelope of output piezoelectric signal was extracted in twice, a voltage amplitude curve with a sinusoidal distribution was obtained, which could describe the change of acoustic power. Under different drive voltage of the transducer, the maximum peak voltage of envelope curve was found respectively, their squared values were made a linear fit with acoustic power measured by sound power meter, then the proportional coefficient of theoretical relational expression was calibrated. The experimental results presented a good linear correlation, and the relative error between calibrated theoretical sound power and thatmeasured by sound power meter was less than 8.7%, which proved the feasibility of measuring acoustic power of transducer by piezoelectric transient response.