SU1753626A1 - Method of nondestructive testing of piezoceramic converter - Google Patents

Abstract

The invention relates to instrumentation and can be used to control piezoceramic transducers during their design, manufacture and operation. The purpose of the invention is to improve the accuracy of control of piezo transducers with acoustic isolation from the housing. The measured values of the oscillatory velocity and the electrical voltage at the resonance frequency under mechanical excitation of the body of the piezotransducer make it possible to evaluate simultaneously the mechanical and electrical properties and make a decision about the suitability of the piezotransducer according to the ratio, Ul, 2Vl.2fl, 2 resonant frequency of isolation at the outputs of the reference and controlled transducers, respectively. 2 Il.

Description

The invention relates to instrument-making, in particular, to methods of non-destructive testing of electroacoustic transducers, and can be used to control piezo-ceramic transducers during their design, manufacture and operation.

The aim of the invention is to increase the reliability of monitoring piezo transducers with acoustic isolation from the housing.

Figure 1 shows the structural diagram of the device that implements the method; 2 shows the normalized relationship of relationship A

vp up

f / fn in the analyzed frequency range, where fn is the normalizing frequency; Vp and UP are the values of the amplitudes of the oscillatory velocity at

/ on frequency

the working surface of the transducer; and the electric voltage at its output at the frequency of the decoupling resonance.

The method of non-destructive testing of piezoceramic transducers is carried out as follows.

Using an electric signal generator 1, the vibration table 2 mechanically excites the body of the reference and controlled piezoelectric transducers 3 by harmonic influence of a constant amplitude in the frequency range from 0.05fo to 0.3f0, where f0 is the frequency of the fundamental resonance of the converter. Using the shaker 4, mounted on the working surface of the transducer, and the vibration measurement unit 5, measure the amplitude of the vibrational velocity V of the working surface of the piezo transducers in the indicated frequency diao

with

Vj

sl with about

pazone. The maximum value of this amplitude determines the resonance of the acoustic separation, the frequency fp of which is measured using a frequency meter b. At the same time, on the electrical side of the piezotransducer, with the aid of a voltmeter 7, the magnitude of the electrical voltage, which is the electrical response of the piezoelectric transducer to the mechanical effects of its body, is measured. These measurements are measured as reference and monitored transducers. According to the measurement results, the ratio is

UiV2fi-UaVif2,

where Ui, Da are the values of the electrical voltage at the output, respectively, of the reference and controlled converters;

Vi, Va are the values of the amplitudes of the oscillatory velocity, respectively, for the reference and controlled transducers;

fi, h — values of the resonant — acoustic frequency of the acoustic isolation for the g-talon and controlled transducers.

On the basis of experimental studies, it has been established that, when performing this equality with an accuracy of ± 5%, the controlled transducer qualifies as defect-free with a probability of a correct estimate of 0.95. This accuracy is due to the statistical scatter of experimental data.

Fig. 2 shows the characteristic (curve 8) normalized frequency response in the specified frequency range for the reference and defective (curve 9) transducers. In addition, in a transducer with a poor acoustic, the decoupling resonance frequency is higher.

The main advantage of the method is that it allows to increase the accuracy of the control. This is due to the fact that, by controlling the mechanical and electrophysical parameters of the oscillating system of the converter, it also allows you to control the quality of the acoustic isolation of the oscillatory system and the housing of the converter.

In addition, in the method there is no need in the monitoring process to bring the controlled transducer into subcritical regimes, in which fatigue phenomena intensively develop and defects develop.

Claims (1)

Invention Formula A method of non-destructive testing of a piezo-ceramic transducer, including excitation of controlled and reference transducers, measurement of the oscillatory velocity on a mechanical the side of the transducers and the verification of the condition of faultlessness, which means that, in order to increase the reliability when monitoring transducers with acoustic isolation from the housing, prior to the excitation of the controlled and reference transducers, their resonant frequencies are determined, and the excitation is carried out by harmonic mechanical action of constant amplitude in the frequency range of 0.05-0.3 of the corresponding resonant frequency, the frequencies at which the maximum values of the electrical voltage at the outputs of the transducers are measured, the amplitude of the oscillatory velocity on the mechanical side of the transducers V at these frequencies is measured, and the verification of the condition of the defect-free are based on the ratio UiV2fi U2Vif2, where Ui and U2 are the values of the electrical voltage at the output, respectively, of the reference and controlled converters; Vi and V2 are the values of the amplitudes of the oscillatory velocity, respectively, for the reference and controlled transducers; fi and h are the values of the resonant frequency of the acoustic isolation for the reference and controlled converters; indices 1, 2 correspond to the reference and controlled converters, respectively. one one L, W 09- Q & (C 05 № OD 02 W 1 8 x x 3