CN100439929C - Transverse piezoelectric strain constant measuring method by piezoelectric material quasistatic method and system thereof - Google Patents

Abstract

The invention relates to a measuring method and system for d31 piezoelectric constant that adopts quasi-static method to testing d21 piezoelectric. The system is made up of energizing equipment and circuit equipment. The energizing equipment supplies acting force to testing sample by special stressing accessory. Circuit equipment supplies electric driving signal and taking amplifying and processing to low frequency alternating voltage signal, and display d31 piezoelectric constant. It has the advantages of easy to operate, rapid and accurate.

Description

Horizontal piezoelectric strain constant measuring method of piezoelectric quasi-static method and system

Technical field

The present invention relates to a kind of measuring method of piezoelectric piezoelectric constant, particularly relate to the horizontal piezoelectric strain constant of piezoelectric and (be called for short d ₃₁Piezoelectric constant) a kind of measuring method and measuring system.

Technical background

Piezoelectric constant is the important parameter that characterizes the piezoelectric piezoelectric property, mainly includes vertical piezoelectric strain constant d ₃₃But (patent that measuring method REFERENCE TO RELATED people was authorized on February 6th, 99 " the vertical piezoelectric strain constant measuring instrument of quasi-static method, the patent No. is: ZL97231420.2), horizontal piezoelectric strain constant d ₃₁, tangential piezoelectric strain constant d ₁₅And etc. static pressure piezoelectric constant d _hDeng.For horizontal piezoelectric strain constant d ₃₁Measurement, adopted dynamic method and static method to carry out in the past, dynamic method is measured horizontal piezoelectric strain constant d ₃₁, be to obtain through calculating after resonance by measuring tested sample and the anti-resonance frequency, be the higher a kind of d of measuring accuracy that generally acknowledges in the world at present ₃₁The piezoelectric constant measuring method, but the dynamic method test process is loaded down with trivial details, requires in the measurement to satisfy certain boundary condition and shielding requirements, and limitation is big, can only measure the standard sample (for example: approach rectangular or thin discs) that satisfies given shape, specification and dimensional requirement, poor practicability.Static method is measured d ₃₁Piezoelectric constant is to utilize direct piezo electric effect that piezoelectric has to measure its piezoelectric voltage value obtain d behind acting force by tested sample being applied a folk prescription ₃₁Value, but bigger for guaranteeing to measure the static action power that sensitivity applied in measurement, because the non-linear and pyroelectricity drift phenomenon that piezoelectric had has caused the big and poor repeatability of measuring error.

Summary of the invention

The objective of the invention is to solve the piezoelectric of dynamic method measurement in the past d ₃₁The piezoelectric constant test process is loaded down with trivial details, the defective of poor practicability, and solve static method measurement d ₃₁The problem of the big and poor repeatability of piezoelectric constant error, thus provide a kind of be suitable for that can measure, simple and practical and can satisfy the d of measuring accuracy requirement to the piezoelectric of different shape ₃₁Piezoelectric constant quasistatic measuring method and system.

According to d ₃₁The piezoelectric constant definition:

${\mathrm{<figure-callout\; id="31"\; label="d"\; filenames="C20051012622500132.png,C20051012622500141.png"\; state="\{\{state\}\}">d</figure-callout>}}_{31}={\left(\frac{D_3}{T_1}\right)}^E={\left(\frac{S_1}{E_3}\right)}^T---\left(1\right)$

Herein, D ₃, E ₃Be respectively electric displacement and electric field intensity, T ₁, S ₁For with the perpendicular stress and strain of polarised direction, when the acting force that tested sample is provided is a low-frequency sine alternating force, its frequency is during far below the natural resonance frequency of this sample, stress and strain in the sample is evenly distributed basically, thereby be counted as quasistatic, formula (1) but abbreviation be:

${\mathrm{<figure-callout\; id="31"\; label="d"\; filenames="C20051012622500132.png,C20051012622500141.png"\; state="\{\{state\}\}">d</figure-callout>}}_{31}=\frac{Q/B}{F/A}=\frac{\mathrm{QA}}{\mathrm{FB}}=\frac{\mathrm{CVA}}{\mathrm{FB}}---\left(2\right)$

Here, A is the area of stress application, and B is for producing the area of charge Q, and F is the low-frequency alternating power that is applied, and C is the big electric capacity in parallel with sample, measures d to satisfy ₃₁The time the steady electric field boundary condition, its C value is by the decision of the size of sample; The piezoelectric voltage of V for being produced at big capacitor C two ends owing to piezoelectric effect.

According to d ₃₃Piezoelectric constant is defined as:

${\mathrm{<figure-callout\; id="33"\; label="d"\; filenames="C20051012622500132.png,C20051012622500141.png"\; state="\{\{state\}\}">d</figure-callout>}}_{33}={\left(\frac{D_3}{T_3}\right)}^E={\left(\frac{S_3}{E_3}\right)}^T---\left(3\right)$

Herein, D ₃, E ₃Be respectively electric displacement and electric field intensity, T ₃, S ₃Be the stress and strain consistent with polarised direction, in like manner under the quasistatic measuring condition, formula (3) can be reduced to:

${\mathrm{<figure-callout\; id="33"\; label="d"\; filenames="C20051012622500132.png,C20051012622500141.png"\; state="\{\{state\}\}">d</figure-callout>}}_{33}=\frac{Q/A}{F/A}=\frac{Q}{F}=\frac{\mathrm{CV}}{F}---\left(4\right)$

Herein, A is stress application and the area that produces charge Q (because stress and strain is consistent with polarised direction), and F is the low-frequency alternating power that is applied, and C is the big electric capacity in parallel with sample, equally in order to provide one to satisfy measurement d ₃₃The time the steady electric field boundary condition, its C value is by the decision of the size of sample; The piezoelectric voltage of V for being produced at big capacitor C two ends owing to piezoelectric effect.

The object of the present invention is achieved like this, according to d ₃₁The definition of piezoelectric constant is adopted by tested sample directly being applied low-frequency alternating power and measuring tested sample because the quasistatic method of the low frequency piezoelectric voltage that direct piezo electric effect produces obtains the d of tested sample ₃₁Piezoelectric constant is introduced inner comparative sample for making the measurement simple possible, with vertical piezoelectric constant d of inner comparative sample ₃₃Value is as benchmark, adopts relative method and obtains the d of tested sample ₃₁Piezoelectric constant.

The horizontal piezoelectric strain constant measuring method of piezoelectric quasi-static method provided by the invention (employing relative method) may further comprise the steps:

1) with tested sample and inner comparative sample (vertical piezoelectric constant d ₃₃Value is for known) connect on the mechanics, make the size of both suffered acting forces consistent, simultaneously, inner comparative sample be subjected to force direction consistent with its polarised direction, to satisfy its vertical piezoelectric constant d ₃₃Afterburning requirement; Tested sample be subjected to force direction vertical with polarised direction, to satisfy its horizontal piezoelectric constant d ₃₁Afterburning requirement;

2) the big electric capacity of tested sample and inner comparative sample two ends same capability in parallel is to satisfy d ₃₁And d ₃₃Needed steady electric field condition during measurement;

3) tested sample and inner comparative sample are applied same low-frequency alternating acting force, because direct piezo electric effect produces horizontal piezoelectric charge on the polarized electrode face of tested sample, produce vertical piezoelectric charge on the polarized electrode face of inner comparative sample, the two-way piezoelectric charge converts two-way piezoelectric voltage signal to by electric capacity in parallel separately;

4) utilize the known vertical piezoelectric constant d of inner comparative sample ₃₃Value and by apply that same low-frequency alternating power obtains tested and the physical dimension (area of polarized electrode and lifting surface area) of two-way piezoelectric voltage value and tested sample relatively, according to following formula:

${\mathrm{<figure-callout\; id="31"\; label="d"\; filenames="C20051012622500132.png,C20051012622500141.png"\; state="\{\{state\}\}">d</figure-callout>}}_{31}=d_{33}\frac{A}{B}\frac{V_1}{V_2}---\left(5\right)$

Calculate the d of tested sample ₃₁Piezoelectric constant.

The principle of work of the horizontal piezoelectric strain constant measuring method of quasi-static method provided by the invention is: for tested sample, establishing suffered acting force is F ₁, lifting surface area is A, the area of polarized electrode is B, the tested sample two ends big electric capacity in parallel be C ₁, because the piezoelectric charge that piezoelectric effect produces on electrode surface B is Q ₁, by and the United Nations General Assembly's capacitor C ₁The piezoelectric voltage of last generation is V ₁, according to the d of formula (2) ₃₁The piezoelectric constant definition can get:

${\mathrm{<figure-callout\; id="31"\; label="d"\; filenames="C20051012622500132.png,C20051012622500141.png"\; state="\{\{state\}\}">d</figure-callout>}}_{31}=\frac{Q_1/B}{F_1/A}=\frac{Q_{1}A}{F_{1}B}=\frac{C_1{V}_{1}A}{F_{1}B}---\left(6\right)$

For inner comparative sample, establishing suffered acting force is F ₂, the area of lifting surface area and polarized electrode is A (because sample be subjected to the force direction identical with self polarised direction), two ends big electric capacity in parallel be C ₂, because the piezoelectric charge that piezoelectric effect produces on electrode surface A is Q ₂, in institute and the United Nations General Assembly's capacitor C ₂The piezoelectric voltage of last generation is V ₂, according to the d of formula (4) ₃₃The piezoelectric constant definition can get:

${\mathrm{<figure-callout\; id="33"\; label="d"\; filenames="C20051012622500132.png,C20051012622500141.png"\; state="\{\{state\}\}">d</figure-callout>}}_{33}=\frac{Q_2/A}{F_2/A}=\frac{Q_2}{F_2}=\frac{C_2{V}_2}{F_2}---\left(7\right)$

Because tested sample is identical with the electric capacity of inner comparative sample two ends difference parallel connection, that is: C ₁=C ₂Because tested sample is connected on mechanics with inner comparative sample, both are stressed identical, then: F again ₁=F ₂The d of tested sample ₃₁The d of piezoelectric constant and inner comparative sample ₃₃The ratio of piezoelectric constant is seen following formula:

$\frac{d_{31}}{{\mathrm{<figure-callout\; id="33"\; label="d"\; filenames="C20051012622500132.png,C20051012622500141.png"\; state="\{\{state\}\}">d</figure-callout>}}_{33}}=\frac{\frac{C_1{V}_{1}A}{F_{1}B}}{\frac{C_2{V}_2}{F_2}}=\frac{V_{1}A}{V_{2}B}=\frac{A}{B}\frac{V_1}{V_2}---\left(8\right)$

Because inner comparative sample is constant in measurement, then its d ₃₃The piezoelectric constant value is known, can directly measure by enough slide calliper rule because of the lifting surface area of tested sample and the area of generation electric charge again, therefore can pass through to measure the piezoelectric voltage value V on tested sample and the inner comparative sample two ends shunt capacitance ₁And V ₂And obtain the d of tested sample ₃₁Piezoelectric constant, formula (or the formula in formula 5 and the claim 1) as follows.

${\mathrm{<figure-callout\; id="31"\; label="d"\; filenames="C20051012622500132.png,C20051012622500141.png"\; state="\{\{state\}\}">d</figure-callout>}}_{31}=d_{33}\frac{A}{B}\frac{V_1}{V_2}$

In technique scheme, the frequency of described low-frequency alternating acting force is about 110 hertz, and the amplitude of low-frequency alternating power is 0.2 newton, and tested sample and inner comparative sample two ends big electric capacity in parallel respectively is 1 microfarad.

The horizontal piezoelectric strain constant measuring system of piezoelectric quasi-static method provided by the invention (see figure 2) comprises force application apparatus and circuit arrangement, and wherein force application apparatus includes: electromagnetic driver, special-purpose afterburning annex (see figure 3) and inner comparative sample;

Described electromagnetic driver is made of magnet steel 33, yoke core 36, outer yoke 34, yoke base 35, coil 32, piston 31 and centring disk 30, wherein the upper end of coil 32 links to each other with the lower end of piston 31, be fixed on by centring disk 30 on the end face of outer yoke 34, the live part of coil 32 (winding portion) is outstanding to be placed in the gap, magnetic field that is made of magnet steel 33, yoke core 36 and outer yoke 34, when coil 32 inserted the low-frequency sine drive signal, can doing up and down in above-mentioned magnetic field, rectilinear motion also passed through the low-frequency sine alternating force that piston 31 produces vertical direction;

Last afterburning disk 1 and following afterburning disk 3, positioning link 16, static probe 17, mobile probe 18, mobile probe gib screw 19, base 20 and base gib screw 21 that the afterburning annex of described special use is made by insulating material are formed, wherein go up afterburning disk 1 and be fixed on the crossbeam extended tip place of positioning sliding block 25 in the force application apparatus, the center that following afterburning disk 3 passes round positioning film 28 links to each other with insulation joint pin 4; Positioning link 16 assigns into down on the pilot hole of afterburning disk 3, and the screw that screwed static probe 17 passes positioning link 16 can be rotated the location; Base 20 is stuck on main casing 22 and the set collar 29, and is fixing by base gib screw 21, and the circular hole that mobile probe 18 passes on the base 20 passes through mobile probe gib screw 19 location and fixing; The last afterburning disk 1 of special-purpose afterburning annex and following afterburning disk 3 are used for tested sample 2 is applied vertical vertical, the position of rotation static probe 17 and adjusting mobile probe 18 can make two electrode surfaces (the B direction among Fig. 3 and Fig. 4) of two probes and tested sample 2 closely contact, draw tested sample owing to the piezoelectric electro signal that piezoelectric effect produced, special-purpose afterburning annex can provide longitudinal force and obtain piezoelectric electro signal (see figure 3) from horizontal (or radially) the piece type or the tubular type tested sample of certain specification size;

Described inner comparative sample adopts piezoceramic material to make (also can make of other piezoelectric), has stable piezoelectric property, its d ₃₃It is very little that piezoelectric constant in time, temperature, humidity change the influence that is produced, and it is as tested sample d ₃₁The benchmark that piezoelectric constant is measured is installed in force application apparatus inside, connects both stressed unanimities on mechanics with tested sample.

Described circuit arrangement is made up of two-way prime amplifier 9 and 10, oscillator 11, power amplifier 12, data input unit 13, data processing section 14 and demonstration output 15, and wherein the output of oscillator 11 links to each other with the input of power amplifier 12; Prime amplifier 9 links to each other with the big electric capacity of tested sample 2 with comparative sample 6 two ends parallel connections respectively with 10 input, all insert data processing sections 14 prime amplifier 9 and 10 output and data input unit 13, the output of data processing section 14 with show that output 15 links to each other.

11, one sine voltage signal generators of described oscillator, oscillation frequency is about 110Hz;

Described power amplifier 12, its output power only are 5 watts and adjustable continuously, and the output signal of sine wave signal generator inserts the electromagnetic driver coil after power amplifier amplifies, and can make maximum 1 newton's of generation of electromagnetic driver low-frequency sine alternating force;

Described two-way prime amplifier 9 and 10 is respectively applied for tested and comparison two-way piezoelectric voltage signal V ₁With V ₂Amplify, its input impedance is about 200K Ω, gain margin 60-80db;

Described data input 13, be used to import the lifting surface area and the polarization area (A and B) of tested sample, be the inputs of three decimal numbers, the lifting surface area that its input content is a tested sample and polarization area are than (lifting surface area can measure with slide calliper rule easily with the polarization area);

Described data processing 14 is made up of synchronous linear detector, analog divider and A/D conversion portion, is used for the V after amplifying ₁With V ₂And other data existing or input handle and calculate, to obtain tested sample d ₃₁Piezoelectric constant.Two-way low-frequency alternating voltage V after amplifying ₁With V ₂At first be converted to the two-way d. c. voltage signal, then with the tested sample lifting surface area A of input, the d of polarization area B and inner comparative sample by synchronous linear detector ₃₃The piezoelectric constant value is sent into simulation multiplier-divider (5) calculating d by formula ₃₁The analog value of piezoelectric constant is changed the tested sample d that calculates by A/D then ₃₁The piezoelectric constant analog value is converted into digital quantity value;

Described demonstration output 15 is made up of 4 LED charactrons position of putting in marks, can be with the tested sample d that measures ₃₁Piezoelectric constant value and polarity show output.

The groundwork process of the horizontal piezoelectric strain constant measuring system of piezoelectric quasi-static method provided by the present invention is as follows: at first provide the signal of the low-frequency sine about 110 hertz by oscillator in the circuit arrangement, after amplifying, power amplifier send the low-frequency sine alternating force that electromagnetic driver produces about 0.2 newton in the force application apparatus to be applied on tested sample (it is vertical to add force direction and sample self polarised direction) and the inner comparative sample (it is consistent to add force direction and sample self polarised direction), because piezoelectric effect is carried out data processing, the tested sample d that at last obtain with the tested sample size of input at the two-way piezoelectric voltage signal that produces on tested sample and the inner comparative sample again after prime amplifier amplifies ₃₁Piezoelectric constant value and polarity directly show output.

The invention has the advantages that: the frequency of the sinusoidal wave low-frequency alternating power of selecting for use in the measurement is about 110 hertz, natural resonance frequency far below general tested sample, so the stress and strain in the tested sample is evenly distributed basically, measures required boundary condition and is guaranteed; Because the low-frequency alternating power amplitude that is applied on the sample when measuring only is about 0.2 newton, acting force far below dozens of newton in the static method measurement, effectively avoid the generation of piezoelectric unintentional nonlinearity and pyroelectricity drift phenomenon, reduced measuring error, guaranteed measuring accuracy; Owing to adopt relative method in measuring, tested sample is connected on mechanics with inner comparative sample, calculates d in the data handling procedure again ₃₁The sinusoidal wave low-frequency alternating acting force that is applied during piezoelectric constant not only can divide out (seeing formula 8 and formula 5), and in afterburner process, regulate force application apparatus and also can offset the static pressure deviation that the tested sample tightness is caused, simultaneously owing to tested sample d in measuring ₃₁Piezoelectric constant is with inner comparative sample d ₃₃Piezoelectric constant is a benchmark, therefore, measures the d that not only can obtain tested sample ₃₁The piezoelectric constant value can also obtain tested sample d ₃₁The polarity of piezoelectric constant makes the measurement result practicability and effectiveness.

Description of drawings

Fig. 1 is d of the present invention ₃₁The schematic diagram of piezoelectric constant quasistatic measuring method

Fig. 2 is d of the present invention ₃₁Piezoelectric constant quasistatic measuring system structural representation

Fig. 3 is d of the present invention ₃₁The piezoelectric constant quasistatic is measured special-purpose afterburning accessory structure synoptic diagram

Fig. 4 is d of the present invention ₃₁The piezoelectric constant quasistatic is measured the force application apparatus structural representation

Fig. 5 is d of the present invention ₃₁The piezoelectric constant quasistatic is measured the example structure synoptic diagram

The drawing explanation

Afterburning disk under the last afterburning disk 2-tested sample 3-of 1-

4-insulation joint pin 5-relatively goes up probe 6-comparative sample

7-is probe 8-electromagnetic driver B-tested sample electrode surface relatively down

The 9-first prime amplifier 10-second prime amplifier 11-oscillator

12-power amplifier 13-data input 14-data processing

15-shows output 16-static probe positioning link 17-static probe

18-mobile probe 19-mobile probe gib screw 20-base

21-base gib screw 22-main casing 23-positioning guide rail

24-guide-track groove lid 25-positioning sliding block 26-adjuster bar

The round positioning film 29-of 27-control hand wheel 28-set collar

30-centring disk 31-piston 32-coil

The outer yoke 35-yoke base of 33-magnet steel 34-

36-yoke core 37-signal input gang socket

Embodiment

Further describe measuring method of the present invention and system in conjunction with above-mentioned drawings and Examples now.

With reference to figure 2 and 5, make the horizontal piezoelectric strain constant measuring system of piezoelectric quasi-static method that a present embodiment is made up of force application apparatus and circuit arrangement.

Electromagnetic driver in the present embodiment force application apparatus is with reference to figure 4, by magnet steel 33, yoke core 36, outer yoke 34, yoke base 35, coil 32, piston 31 and centring disk 30 constitute, its China and foreign countries' yoke 34 is fixed on the yoke base 35, the upper end of coil 32 links to each other with the lower end of piston 31, be fixed on by centring disk 30 on the end face of outer yoke 34, the winding portion of coil 32 is outstanding to be placed on by magnet steel 33, in the gap, magnetic field that yoke core 36 and outer yoke 34 constitute, when inserting the low-frequency sine drive signal, can doing up and down in above-mentioned magnetic field, rectilinear motion also passes through the low-frequency alternating power that piston 31 produces vertical direction.

With reference to figure 3, last afterburning disk 1 and following afterburning disk 3 that the special-purpose afterburning annex of present embodiment is made by epoxy plate, static probe 17 that stainless steel material is made and its positioning link 16, mobile probe 18 and its gib screw 19, base 20 and base gib screw 21 are formed, upward afterburning disk 1 is fixed on the crossbeam extended tip place of positioning sliding block 25 in the force application apparatus, and the center that following afterburning disk 3 passes round positioning film 28 links to each other with insulation joint pin 4; Positioning link 16 assigns into down on the pilot hole of afterburning disk 3, and the screw that screwed static probe 17 passes positioning link 16 can be rotated the location; Base 20 is stuck on main casing 22 and the set collar 29, and is fixing by base gib screw 21, and the circular hole that mobile probe 18 passes on the base 20 can move horizontally and fix by gib screw 19.Signal input gang socket 37 is installed on the outer wall of main casing 22.Going up afterburning disk 1 is used for tested sample 2 is applied vertical vertical with following afterburning disk 3, the position of rotation static probe 17 and adjusting mobile probe 18 can make two electrode surfaces (the B direction among Fig. 3 and Fig. 4) of two probes and tested sample 2 closely contact, draw tested sample owing to the piezoelectric electro signal that piezoelectric effect produced, special-purpose afterburning annex can provide longitudinal force and obtain piezoelectric electro signal (see figure 3) from horizontal (or radially) the piece type or the tubular type tested sample of certain specification size

Inner comparative sample 6 is to be born by the column type piezo ceramic element that PZT-5 type piezoceramic material is made, and its diameter is 6 millimeters, highly is 5 millimeters, through after the sufficient digestion time, and its d ₃₃Piezoelectric constant is stable, is 400pC/N, and the polarized electrode face is the upper and lower end face of cylinder, and the positive pole of upper surface during for polarization and relatively gone up probe 5 and be connected; Negative pole when the lower surface is polarization is connected with relatively more following probe 7.

Be connected to prime amplifier 9 and 10 (with reference to figure 1) in the circuit arrangement by cable behind the electric capacity of the two ends of static probe 17 and mobile probe 18 and each one 1 microfarad in parallel of 5 and 7 two ends of popping one's head in more up and down, the input impedance of two-way prime amplifier is 200K Ω, it is also identical to gain, and is 80db.

With reference to figure 2, the circuit arrangement of present embodiment also comprises oscillator 11, power amplifier 12, data input unit 13, data processing section 14 and shows output 15 except the identical prime amplifier 9 of two-way performance and 10.

Here the square type sample that a PZT-5 type piezoceramic material is made (length is 15 millimeters) carries out d ₃₁The process of the measurement of piezoelectric constant is as follows:

With reference to figure 5, at first the force application apparatus in the horizontal piezoelectric strain constant measuring system of piezoelectric quasi-static method is connected with circuit arrangement (can with reference to the relevant explanation among the embodiment 1), then square type tested sample (2) is placed on down the centre above the afterburning disk (3), positive electrode one end and static probe (17) during the sample polarization join, and negative electrode one end and mobile probe (18) join, regulating mobile probe (18) makes two electrode surfaces of square type tested sample (2) closely contact with static probe (17) mobile probe (18), and utilize mobile probe gib screw (19) to be fixed, then, the control hand wheel (27) of rotation force application apparatus makes positioning sliding block (25) move up and down and drive afterburning disk (1) and moves up and down square type tested sample (2) is pushed down, open the switch of circuit arrangement in the system, oscillator (11) work, the generation oscillation frequency is that the sine-wave oscillation signal of 110Hz send electromagnetic driver in the force application apparatus after power amplifier (12) amplifies, the alternating force that is converted to same frequency acts on inner comparative sample (6) of column type and the square type tested sample (2), because the two-way low-frequency alternating voltage that piezoelectric effect is produced on the shunt capacitance of the inner comparative sample (6) of square tested sample (2) and column type two ends is sent into the synchronous linear detector detection in the data processing section (13) after through the prime amplifier (9) that is connected separately and (10) amplification respectively, obtained the corresponding DC voltage V1 of low-frequency alternating voltage with square tested sample (2), its polarity is for negative, the corresponding DC voltage V2 of low-frequency alternating voltage with the inner comparative sample of column type (6), its polarity is for just, (15mm * 15mm) ratio is 1, by the dial input " 1.00 " of data inputs (13) and the d of the inner comparative sample of column type (6) because square tested sample (2) lifting surface area is identical with the polarization area ₃₃Piezoelectric constant " 400pC/N " is sent the d of simulation multiplier-divider by relative method in the quasi-static method measurement together ₃₁Computing formula, the d of calculating square tested sample (2) ₃₁Piezoelectric constant is also carried out the A/D conversion, and the measurement result that obtains at last is " 212pC/N ".More than be to adopt the horizontal piezoelectric strain constant measuring system of embodiments of the invention 1 piezoelectric quasi-static method to square tested sample d ₃₁The complete procedure that piezoelectric constant is measured, from the square tested sample put on request the special-purpose afterburning annex of measuring system force application apparatus fixing after, circuit arrangement starts in the measuring system, finish by vibration drive that output, signal input are amplified, data processing shows the overall process work of output to final measurement, only need several seconds, maximum tens seconds time.

Claims (3)

1. the horizontal piezoelectric strain constant measuring method of the quasi-static method of a piezoelectric may further comprise the steps:

1) connect on tested sample and the inner comparative sample mechanics, make the size of both suffered acting forces consistent, simultaneously, inner comparative sample be subjected to force direction consistent with its polarised direction, to satisfy its vertical piezoelectric strain constant d ₃₃Afterburning requirement; Tested sample be subjected to force direction vertical with polarised direction, to satisfy its horizontal piezoelectric strain constant d ₃₁Afterburning requirement;

2) the big electric capacity of tested sample and inner comparative sample two ends same capability in parallel is to satisfy d ₃₁And d ₃₃Needed steady electric field condition during measurement;

3) tested sample and inner comparative sample are applied same low-frequency alternating acting force, the frequency of described low-frequency alternating acting force is 110Hz; The amplitude of low-frequency alternating acting force is 0.2 newton; Because direct piezo electric effect produces horizontal piezoelectric charge on the polarized electrode face of tested sample, produce vertical piezoelectric charge on the polarized electrode face of inner comparative sample, the two-way piezoelectric charge converts two-way piezoelectric voltage signal to by electric capacity in parallel separately;

4) utilize the known vertical piezoelectric strain constant d of inner comparative sample ₃₃Value and by apply that the low-frequency alternating acting force obtains tested and two-way piezoelectric voltage value relatively, and the area of the polarized electrode of tested sample and lifting surface area, according to following formula:

$d_{31}=d_{33}\frac{A}{B}\frac{V_1}{V_2}$

Calculate the horizontal piezoelectric strain constant d of tested sample ₃₁

Wherein, A is the area of stress application, and B is for producing the area of charge Q;

V ₁Piezoelectric voltage for the tested sample generation; V ₂Piezoelectric voltage for inner comparative sample generation.

2. by the horizontal piezoelectric strain constant measuring method of quasi-static method of the described piezoelectric of claim 1, it is characterized in that described inner comparative sample is the column type piezoelectric element that piezoceramic material is made.

3. the horizontal piezoelectric strain constant measuring system of the quasi-static method of a piezoelectric comprises force application apparatus and circuit arrangement; Described circuit arrangement is by two-way prime amplifier (9,10), oscillator (11), power amplifier (12), data input unit (13), data processing section (14) and show output (15) composition; Wherein two-way prime amplifier (9,10) input impedance is 200 kilo-ohms, and gain margin is 60-80db, is used for tested and comparison two-way piezoelectric voltage signal are amplified; Data input unit (13) is three decimal numbers input, is used to import the ratio of tested sample lifting surface area and polarization area; Data processing section (14) is electrically connected by synchronous linear detector, analog divider and A/D conversion portion to be formed, be used for according to measuring obtain tested and two-way piezoelectric voltage signal relatively, and other correlation parameter calculates the horizontal piezoelectric strain constant d of tested sample ₃₁Value; Show that output (15) is made up of four LED charactrons position of putting in marks, be used to show the net result of measurement; Oscillator (11) and power amplifier (12) are used to the electromagnetic driver in the force application apparatus that drive signal is provided;

Described force application apparatus by be used for producing the electromagnetic driver of low-frequency alternating acting force, as a comparison the method measuring basis the inside comparative sample and be used for providing the afterburning annex of measuring required acting force and acquisition piezoelectric electro signal to form to tested sample; Described electromagnetic driver is made of magnet steel (33), yoke core (36), outer yoke (34), yoke base (35), coil (32), piston (31) and centring disk (30), wherein the upper end of coil (32) links to each other with the lower end of piston (31), be fixed on the end face of outer yoke (34) by centring disk (30), the winding portion of coil (32) is outstanding to be placed in the gap, magnetic field that is made of magnet steel (33), yoke core (36) and outer yoke (34); It is characterized in that,

Last afterburning disk (1) and following afterburning disk (3), static probe (17), positioning link (16), mobile probe (18), mobile probe gib screw (19), base (20) and base gib screw (21) that described afterburning annex is made by insulating material are formed; Described afterburning disk (1) is fixed on the crossbeam extended tip place of positioning sliding block in the force application apparatus (25), and the center that following afterburning disk (3) passes round positioning film (28) links to each other with insulation joint pin (4); Positioning link (16) assigns into down on the pilot hole of afterburning disk (3), and screwed static probe (17) passes the screw of positioning link (16) and fixes; Base (20) is stuck on main casing (22) and the set collar (29), fixes by base gib screw (21), and mobile probe (18) can move horizontally in the circular hole on the base (20), and by its gib screw (19) location and fixing.

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