Acoustics-Characteristics and measurements of ultrasonic piezoelectric transducers up to 100 kHz
Some standard content:
GH/T 17252—1998
This standard is formulated with reference to the International Electrotechnical Commission Technical Report IEC1088:1991 "Characteristics and Measurement of Ultrasonic Piezoelectric Ceramic Transducers". The writing rules comply with the provisions of GB/T1.1—199.3. This standard is basically the same as the technical report IEC1088 in terms of technical content. There are only the following differences: 1. The name of IFC1088 is "Performance and Measurement of Ultrasonic Piezoelectric Ceramic Transducers". It is applicable to all piezoelectric types. Therefore, the limited range of "ceramic" is removed. On the other hand, in order to avoid confusion, the frequency range applicable to the standard is placed in the name to provide convenience for users. Therefore, we changed the name of this standard to the current "Characteristics and Measurement of Ultrasonic Piezoelectric Transducers Below 100kH2". 2. The content of Chapter 1 "Classification of Transducers" is used in the definition of Chapter 3 of [IEC1088. When formulating this standard, the classification of "P-type transducers" and "A-type transducers" in Chapter + was placed in the definition of Chapter 3. We think this arrangement is more reasonable. 3. Formula (3.7) of IEC 1088 Vv =sm*/2
We believe that it is incorrect and should be Vev=
Appendix A, Appendix B and Appendix C of this standard are indicative. This standard is proposed and approved by the National Technical Committee for Acoustics Standardization. The drafting units of this standard are: Institute of Acoustics, Chinese Academy of Sciences, 715 Institute of China State Shipbuilding Corporation, and the main drafters of this standard are: Zhu Houlang, Xing Yanhong, Shuai Wenjun, Jian Yaoquan. 1 Scope
National Standard of the People's Republic of China
Acoustics-Characteristics and measurements ofultrasonicpiezoeectric transducerg upto 100kHzGB/T 17252--1998
This standard specifies the basic electroacoustic characteristics and measurement methods of piezoelectric transducers for industrial applications of ultrasonic energy. This standard applies to piezoelectric longitudinal vibration transducers with a single resonant frequency below 100 kHz. 2 Referenced standards
The clauses contained in the following standards constitute the clauses of this standard through reference in this standard. When the standard is published, the versions shown are valid. All standards will be revised. Parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T3947—1996 Acoustic Terminology
3 Definitions
This standard adopts the following definitions.
3.↑ Input electrical power P. At a given frequency, the effective AC power absorbed by the transducer from the power generator, in watts, W. Note: Input electrical power can be expressed as:
P,- Vr - Ireost
Where: V---the root mean square value of the transducer input voltage, V: It---the root mean square value of the current passing through the transducer, AI--the phase difference between Vr and II, (\), 3.1.1 Frequency response curve for input electrical power P. (f) The relationship between P. and frequency when the input voltage of the transducer is constant. 3.1.2 Input electriral power P. at resonance The maximum value of the input electrical power frequency response curve. 3.2 Output acoustic power P, output acoustic power The acoustic power radiated into the medium by the transducer, in watts, R. 3.3 P-type transducers transducers for radiating acoustic power into air or liquid. Note: To improve the matching between the transducer and the medium, an impedance matcher connected to the radiating surface of the transducer can be added, which is also an important part of the transducer.
3.4 Category A transducers
ftransducers af category A
Transducers for various solid processing. Note: The mechanical horn connected to the temporary radiating surface of the transducer should be regarded as a component of the transducer. National Technical Supervision High Approved on March 18, 1948. 10-01 Implementation
GB/T17252—1998
3.5 Vibrational displacement amplitude vibrational displacement amplitude The axial component of the vibration displacement amplitude at the center of the processing head or horn of the category A transducer, in micrometers, μm. The vibration displacement amplitude of the P-type transducer is the amplitude of the longitudinal vibration displacement at a given point on the radiating surface. 3.5.1 Frequency response curve of vibration displacement amplitude (f) frequency response curve [or vibrational displacement amplitude]
The relationship curve between the vibration displacement amplitude and frequency when the input voltage of the transducer is constant. 3.5.2 Vibration displacement amplitude at resonance The maximum value of the vibration displacement amplitude when the input voltage of the transducer is constant and the frequency changes: 3.6 Resonance frequency fIrequency of resonance The frequency corresponding to the maximum value of the input power frequency response curve (P-type transducer) or the vibration displacement amplitude frequency response curve (A-type transducer), in kHz.
3.7 Bandwidth fbandwidth
The width between the frequencies on both sides of the f on the transducer frequency response curve corresponding to the value of 0.5P (P-type transducer) or the frequency corresponding to the maximum value of 0.707 (A-type transducer), in kHz. 3.7.1 Mechanical quality factor of the transducer Q The ratio of the resonant frequency to the bandwidth.
3.8 Electrical impedance of the transducer2
At a given frequency, when the transducer is excited as a simple harmonic wave (sinusoidal periodic vibration), the electrical impedance of the transducer at this frequency is the complex ratio of the input voltage of the transducer to the current passing through the transducer, in ohms. Z=R+x
Where R and X are the real and imaginary parts of the impedance, respectively. Note
1 The resistance can also be expressed as:
2= izI(cag +ysing)
IZI= VR*+ Xrtanp
Where: 2|V+/-—absolute value of impedance, effective value is equal to the ratio of the root mean square of the transducer input voltage to the root mean square of the current; 2—phase difference between current and voltage. 2 For high-power operation, when the input impedance is related to the excitation voltage, the excitation voltage should be indicated. 3.8.1 Electrical impedance at resonance Zelectricalimpedanceatresonance The electrical impedance value at the resonance frequency.
Note! The corresponding components of the electrical impedance are expressed as: Rx, 2| and, 3.9 The electrical admittance of the transducer Y is the reciprocal of the electrical impedance, expressed in the following complex form: -G+B
wherein G and B are the real and imaginary parts of the admittance, respectively, in Siemens, S. The relationship between the real and imaginary parts of the admittance and the components of the electrical impedance is: R
G=RiB=R
3.9.1 Electrical admittance of the clamped transducer Y is the electrical admittance of the clamped transducer when the transducer has no mechanical vibration, in Siemens, S. Note: The real and imaginary parts of the electrical admittance are represented by G1.B. respectively. (3)
GB/T17252—1998
Ca -- B./2nf
3.10 Sensitivity of the transducer 3.10.1 “Displacement-voltage” sensitivity Mry “displacement-voltage” sensitivity 6)
The ratio of the vibration displacement amplitude at the resonant frequency to the transducer input voltage amplitude, in micrometers per volt, m/V. It can be expressed as: Meu =
Where: —Amplitude of vibration displacement;
V-.The root mean square value of voltage at the resonant frequency. VTrs
3.10.2* “Displacement-squared-power” sensitivity M “squareddisplacement-pawer” sensitivity The ratio of the vibration displacement amplitude at the resonant frequency to the input electrical power, in micrometers squared per watt (um)\/W. Mn=
Note: “Displacement-squared-power\sensitivity is the electrical degree of efficiency of a class A transducer, 3.11 electroacoustical efficiency nelectroacoustical efficiency The ratio of the acoustic power radiated to the medium by a class P transducer to the input electrical power. =
4 Measurement conditions
4.1 Overview
(8))
Measurements of transducer characteristics should be made as far as possible under the actual working conditions of the transducer, taking due account of important factors such as ambient temperature, cooling, transducer support and type of acoustic load. 4.1.1 Acoustic load
If there are no special requirements for the type of acoustic load, the measurements of type A transducers should be made in air and type P transducers in the working medium. In the case of liquid acoustic loads, the height of the liquid level in the measuring tank and the change in the acoustic power due to cavitation in the medium should be taken into account (see Appendix B).
4.2 Measurement preparation
4.2.1 Transducer preparation
Before immersion in water, all contaminants and oil stains on the transducer and its accessories should be carefully cleaned. If there are no special requirements for the position of the transducer during the measurement, the transducer should be placed in a way that avoids air bubbles on the surface area. 4.2.2 Preparation of water
The water should be heated to above 70℃ to remove gas, then treated with ultrasound with sufficient ultrasonic intensity to produce cavitation for 2h, no additional heating is required, then cooled to the operating temperature, or degassed water at 25℃±5℃ is used. The simplest way to prepare degassed water is to boil the water and keep it for 15min, then cool it to 54℃, fill the bottle, and plug it with a rubber stopper with a glass tube. The glass tube is equipped with a hose, which is clamped after being filled with water: cool and store, and maintain partial vacuum.
Release the clamp when using it and pour it into the water tank to prevent air from entering. 4.3 Measurement conditions
When measuring, the rated value of the AC excitation voltage should be used. It is not allowed to use the parameter values measured under low power conditions to infer the corresponding values under high power conditions:
The excitation voltage value, input power and parameters that affect the measurement results should be recorded together with the measurement results. It should be noted that the input power and vibration extremes should not exceed the frequency specified by the manufacturer. 4.4
GB/T17252-1998
The rated frequency and dynamic range of the excitation power generator and the measuring equipment should meet the requirements of the transducer under test. 5 Measurement of electrical parameters
5.1 Measurement of transducer input voltage
The input voltage of the transducer is directly measured by a voltmeter connected to the input terminal of the transducer. The input impedance of the voltmeter is at least 100 times greater than the impedance of the transducer. The measurement error should not exceed ±1%. 5.2 Measurement of transducer input current
The current at the input terminal of the transducer can be measured directly by connecting a high-voltage ammeter in series with the transducer or by using a current transformer. The measurement error should not exceed ±1.5%.
Note that the transducer input current can be obtained by V./r, where V is the voltage across the small non-reactive resistor rs connected to the transducer. During the measurement, the resistance value should not be less than 0.5% or higher accuracy, and the error of the measured voltage should not exceed ±1%. 5.3 Measurement of the current-voltage phase difference at the transducer input The phase difference can be measured directly using an electronic phase meter. The measurement error should not exceed ±2%. 5.4 Measurement of input electrical power
The input electrical power is measured directly using an electronic wattmeter connected to the input end. The measurement error should not exceed ±5%. Note that the input electrical power can be calculated using formula (1). Vt, I- and can be obtained by actual measurement according to 5.1 to 5.3. 5.5 Measurement of transducer impedance (admittance>
The transducer impedance or admittance can be directly measured using an impedance bridge or an admittance bridge. The measurement error should not exceed ±5%. Note: The impedance value can be calculated using formula (3), and the admittance can be calculated using the following relationship: Y-
(cosgjgin
Where Vt, I and are also based on the measured values of Articles 5.1 to 5.3. 6 Measurement of vibration displacement amplitude
.*+-..-[ 10 3
The vibration displacement amplitude is measured with a reading microscope, which can be adjusted to focus on a point on the special light-illuminating surface of the transducer or the horn. When the transducer is vibrated at a certain ultrasonic frequency, if the vibration is purely axial along the intermediate coordinate, the bright spot becomes a straight line. If the vibration has a lateral component, the straight line has a certain angle. If there is a phase shift between the axial and lateral vibrations, the bright spot forms an ellipse. The projection size of the straight line segment or circle on its central coordinate axis is twice the vibration displacement amplitude. The magnification of the microscope should be in the range of 100 to 500. Amplitudes of not less than 2 can be measured in this way. Note: The vibration displacement amplitude can also be measured directly using a velocimeter or various types of vibration meters. The measurement error should not exceed 2.5%. 7 Characteristics of the transducer 7.1 The resonant frequency and input power of the transducer at resonance The resonant frequency and input power of the transducer at resonance are determined by the frequency response curve of the input power. The power at a given excitation frequency can be measured according to 5.4, and the frequency is measured by an electronic frequency meter. When measuring the frequency response curve, the input voltage of the transducer should be guaranteed to be at the rated value. The type of acoustic load should also be recorded. The input power P of the transducer at resonance is equal to the maximum value of P). The excitation frequency at which the maximum value occurs is equal to the resonant frequency of the transducer. 7.2 Bandwidth and quality factor The bandwidth of the transducer is equal to the difference between the two rated frequencies when P is 0.5P:r on both sides of the frequency response curve of the input power (see 7.1) (see 3.7). The quality factor of the transducer is determined by formula (2). The measurement conditions should meet the rated values of the parameters, and the type of acoustic load should also be recorded. 7.3 Vibration displacement amplitude at resonance GB/T 17252-1998
should be recorded, the difference between the excitation frequency and the resonant frequency should not exceed 0.16f/Q(Hz). 7.4 The "displacement-voltage" sensitivity of the transducer The "displacement-voltage" sensitivity of the transducer can be calculated using formula (7). The vibration displacement amplitude of the transducer and the input effective electric power are determined at the resonant frequency,
7.5 The output sound power of the transducer
The sound power radiated by the transducer to the medium is determined by the frequency response curve of the input electric power: The input electric power is measured under the conditions of specified load and no load of the transducer (see Figure 1). When measuring the frequency response curve of the loaded transducer, the input voltage should be kept at the rated value (see 7.1): For the no-sound load pair, the input voltage should be reduced so that the vibration displacement amplitude is equal to the rated value under normal load conditions: The output sound power of the transducer is calculated by formula (I1); P, = Per Pnu Pel + PtbZxz.net
Where: P: center - input power of the loaded transducer at the resonant frequency (line segment AB in Figure 1); P1 - power loss of the transducer at the resonant frequency (line segment BC in Figure 1); Pi - input power of the unloaded transducer at the resonant frequency "n" (AB in Figure 1); P1 - power loss of the unloaded transducer at the resonant frequency (line segment B center in Figure 1). +--(11)
At the resonant frequency, the input power values of the loaded and unloaded transducers can be calculated according to 7.1 respectively. Corresponding to the resonant frequencies f. and fm, the values of P and P can be calculated by equations (12) and (13): P., - af..
...(12)
The coefficient a can be obtained by the average value of 5 ratios P, (1)//1 in the range of +1 less than f(1-2/Q) and greater than m(1+2/Q). Wherein, is the quality factor of the loaded transducer. The coefficient a can be obtained by the average value of 5 ratios P(:)/f in the range of f1 less than r(1→2/Q) and greater than m(1+2/Q). Q is the quality factor of the unloaded transducer, 7.6 The electroacoustic efficiency of the transducer
The electroacoustic efficiency of the P type transducer is calculated by equation (9). The output sound power P at resonance is obtained according to 7.5; the input electrical power P at resonance is obtained according to 7.1. The type of acoustic load and operating conditions should also be recorded (see 4.3). 7.7 The "displacement square-power\sensitivity" of the transducer The "displacement square-power\sensitivity" of a class A loaded transducer is calculated using formula (8). Input electromotive force P at resonance: obtained according to 7.1; the vibration displacement amplitude at resonance is obtained according to 7.3; the type of acoustic load and measurement conditions should also be recorded. 7.8 Electrical impedance at resonance
The electrical impedance is measured using the method described in 5.5. The input voltage of the transducer should be maintained at the rated value. When measuring the electrical impedance, the difference between the excitation frequency and the resonance frequency should not exceed 0. 01frQ. 7.9 Admittance of clamped transducer
The capacitance and dielectric loss tangent of the clamped transducer (see 3.9.1) can be obtained from the frequency response curve of the transducer electrical impedance (admittance). The components of the electrical impedance (admittance) are obtained at 5 frequency points in the non-resonant region between less than (1-2/Q) and greater than f (1→2/Q) when the excitation voltage is the rated value (according to 5.5). The capacitance of the clamped transducer should be calculated using the average value of the following formula: 1X,
2filR2 + X!
or the mean value of B/2, where R1 and X1 are the real and leg parts of the impedance at a given frequency (B, is the imaginary part of the admittance). The dielectric loss tangent is obtained by the ratio G7B. (G, is the real part of the admittance when suspended at the same frequency). P
GB/T17252—1998
MCN and M,C,N1 are the frequency characteristics of the motor power consumption under load (1) and no load (2) respectively. Figure 1
Frequency characteristics of the input power of the transducer
GB/T 17252—1998
Appendix A
(Suggestive Appendix)
Nonlinear characteristics of transducers
The power and voltage of the invitation signal used in the measurement are determined by the working conditions. The dielectric loss tangent depends on the excitation voltage, the electromechanical loss factor is determined by the vibration displacement amplitude; the electromechanical coupling coefficient is also related to the excitation voltage. Therefore, the bandwidth, quality factor, efficiency and sensitivity of the transducer are also related to the excitation voltage.
Appendix B
(Suggestive Appendix)
Relationship between load impedance and vibration displacement amplitude The sensitivity and efficiency of a typical linear transducer are related to the impedance of the mechanical load. At low vibration displacement amplitudes (non-cavitation region), the negative impedance (In the case of water load without reflection) It is only determined by the medium characteristics and the radiation area. If cavitation occurs, the load impedance will decrease. As shown in Figure B1, in water that is not completely degassed, at a frequency of 28kHz, the load impedance is a nonlinear function of the vibration velocity (proportional to the vibration displacement amplitude) and there is a hysteresis effect.
Increase the vibration velocity amplitude
Reduce the vibration intensity
Zhen Jingms-
Figure B1 Load characteristic impedance Z./S curve as a function of the vibration velocity size 0.25
GB/T17252—1998
Appendix C
(Suggested Appendix)
References
E1] Kolesnikoy AE Acousttcal mezsurements,Leningrad,Sidostroene. 1s83Gin Russian).[2] Physzcat Acoustes, ed., by WP Mason.Vol. l.\Methods and Devices\,Part A.l96t,Academ-Le Press.New Yark and landon.[3] Uitrasonir Transducers+ed,by Y.Kikuchi,Corona Publishing Company,Ltd. .Tokyo,1969.[4J J, Warren Horton, Fundamentals of Somar, US Naval Institute Annapolis, Maryland, 1965.
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