CN105403748A - Measurement apparatus and method for generating pulse voltages on the basis of flexoelectric dynamic effect - Google Patents

Abstract

The invention discloses a measurement apparatus and method for generating pulse voltages on the basis of a flexoelectric dynamic effect. The apparatus comprises a left metal electrode and a right meal electrode which are respectively arranged at the left surface and the right surface of a test piece; the left metal electrode and the right metal electrode are connected with a lead wire of an external resistor, and the resistor is connected in parallel with a display storage device measuring pulse voltage signals through a ground wire. The invention also provides a measurement method. Output voltages of the test piece are measured through a high-speed oscilloscope, and the pulse voltages generated through the flexoelectric dynamic effect can be directly measured in a convenient and simple manner.

Description

A kind of measurement mechanism and method producing pulse voltage based on flexure electro dynamic effect

Technical field

The present invention relates to pulse voltage field of measuring technique, be specifically related to a kind of based on flexure electro dynamic effect produce measurement mechanism and the method for pulse voltage.

Background technology

Stress-electric coupling phenomenon is extensively present in various artificial and natural material.Piezoelectric is a kind of important intellectual material, can produce electric polarization, otherwise can produce mechanically deform in the electric field time this material is subject to mechanical stress effect.When piezoelectric effect refers to and applies external force (pressure or pulling force) effect and be out of shape on dielectric certain orientation, produce electric charge in its surface, and only have asymmetric crystal to produce piezoelectric effect.Flexoelectric effect refers to and produces polarization by heterogeneous strain field or strain gradient, with piezoelectric effect unlike, even if for centrosymmetrical crystal, flexoelectric effect can make material produce electric polarization equally.In solid atomic crystal, strain gradient makes atom have relative displacement heterogeneous, thus the inverting destroying crystal is symmetrical, in crystal, produce polarization.Because piezoelectric effect is produced by homogeneous strain, flexoelectric effect is produced by strain heterogeneous, difference in this mechanism result in flexoelectric effect under macro-scale and often can ignore, and under micro-scale, the strain gradient that size is relevant is very large, and flexoelectric effect can not be left in the basket.Due to the requirement to crystal structure symmetry relative loose, flexoelectric effect is prevalent in various material, comprises non-piezoelectric material and isotropic material.

When high speed impact ripple is by test specimen, there is high strain-rate distortion, produce the strain gradient of the time that depends on, and strain gradient can produce the polarization displacement of ion; For shock compressive wave, the acceleration of atom is proportional to strain gradient, and the acceleration of the ion of different quality produces extra polarization displacement, thus produces flexure electro dynamic effect, produces polarization charge, and flexure electro dynamic effect is normally defined:

$P={\mathrm{\μ}}_d\frac{\∂\mathrm{\ϵ}}{\∂x}$

Wherein μ _d=-χ cM/ ρ is Dynamic flexural electrostrictive coefficient.M is the coefficient calculated by lattice dynamics.ε is the elastic strain of material, and x is the direction of gradient, and P is the polarization that the strain gradient caused by flexoelectric effect produces, and ρ is density, and c is elastic constant.Under International System of Units, the unit of flexoelectric coefficient is C/m.

Flexure electric-type material selection range is wider, and environment and mankind's friendly material can be used to the function elements such as preparation flexure electric-type sensor, driver.Such correlation theory of research flexure electro dynamic effect and the measuring method of generation voltage signal just have very important scientific research engineering significance.Up to now, under shock wave, the measurement mechanism and the method that produce pulse voltage due to flexure electro dynamic effect are still blank, a kind of measurement mechanism and method producing pulse voltage based on flexure electro dynamic effect of present design, directly output charge is measured, experimental technique simple possible by high-speed oscilloscope.

Summary of the invention

In order to overcome above-mentioned prior art Problems existing, the object of the present invention is to provide a kind of measurement mechanism and the method that produce pulse voltage based on flexure electro dynamic effect, by high speed impact ripple compression test specimen, strain gradient is produced in test specimen, thus measure the voltage that produces of flexoelectric effect occurs, also can be used to detect institute and to measure and monitor the growth of standing timber the flexure electro dynamic effect of expecting.

In order to reach above object, the present invention adopts following technical scheme:

Produce a measurement mechanism for pulse voltage based on flexure electro dynamic effect, comprise the left metal electrode 1 and right metal electrode 3 that are separately positioned on test specimen 2 left surface and right surface; Described test specimen 2 and left metal electrode 1 and right metal electrode 3 are encapsulated in epoxy resin 4; Described left metal electrode 1 is connected in series respectively by lead-in wire 5 and resistance 8 with right metal electrode 3; Described resistance 8 is connected in parallel by the display memory storage 7 of ground wire 6 with ranging pulse voltage signal.

Described left metal electrode 1 and right metal electrode 3 form electrode by the method for evaporation in test specimen left and right surface gold-plating.

Described ground wire 6 is connected by the mode of wire bonding with lead-in wire 5 and resistance 8.

The display memory storage 7 of described ranging pulse voltage signal is high-speed oscilloscope.

Measurement mechanism recited above and method, the film flying high velocity impact test specimen 2 of one-stage light-gas gun 9 produces shock wave, there is high strain-rate distortion in test specimen 2, produce strain gradient, polarization charge is produced on test specimen about 2 surface again by flexoelectric effect, test specimen about 2 surface charge to be connected with resistance 8 via lead-in wire 5 by left metal electrode 1 and right metal electrode 3 and is formed closed circuit, and the high-speed oscilloscope 7 in parallel with resistance 8 gathers and show pulse voltage signal;

When high speed impact ripple is by test specimen 2, there is high strain-rate distortion, produce the strain gradient of the time that depends on, and strain gradient can produce the polarization displacement of ion; For shock compressive wave, the acceleration of atom is proportional to strain gradient, and the acceleration of the ion of different quality produces extra polarization displacement, thus produces flexure electro dynamic effect, and produce polarization charge, its expression formula is:

$P=(\mathrm{\μ}+{\mathrm{\μ}}_d)\frac{\∂\mathrm{\ϵ}}{\∂x}=\frac{Q}{H^2}$

U＝kQ

Wherein μ _d=-χ cM/ ρ is Dynamic flexural electrostrictive coefficient, and M is the coefficient calculated by lattice dynamics, and ρ is density, and c is elastic constant; μ is static flexoelectric coefficient, ε is the elastic strain of material, x is the direction of gradient, P is the polarization that the strain gradient caused by flexoelectric effect produces, Q is the output charge of two sides, left and right metal electrode, k is electric charges amplify coefficient, and U is the output quantity of magnitude of voltage, and H is the surperficial length of side about material test specimen; The pulse voltage produced directly can be obtained by formula.

The present invention has the following advantages:

1) up to now, under shock wave, the measurement mechanism of pulse voltage is produced based on flexure electro dynamic effect institute and method is still blank.The present invention has filled up the blank of this respect, for more deep research provides experimental technique and thinking.

2) the external 50 Ω resistance of circuit connected in series of the present invention, are delayed the burst length, to measure more accurately.

3) adopt direct measuring voltage, high-speed oscilloscope directly can measure the change of voltage in tiny time, tests simple and reliable.

4) required excitation instrument is gas-gun, and compared with the quick-fried device of change, the advantage of gas big gun is that velocity of shot is easy to adjustment, film flying stable movement, and experimental data is reproducible, signal testing interference is little, shock wave that is that produce has larger planar range etc.

Accompanying drawing explanation

Accompanying drawing is the structural representation of measurement mechanism of the present invention.

Embodiment

Below in conjunction with the drawings and specific embodiments, the present invention is described in further details.

As shown in drawings, the present invention a kind of based on flexure electro dynamic effect produce the measurement mechanism of pulse voltage, comprise the left metal electrode 1 and right metal electrode 3 that are separately positioned on test specimen 2 left surface and right surface, described left metal electrode 1 contacts with the left surface of test specimen 2; Described right metal electrode 3 contacts with the right surface of test specimen 2; In epoxy resin 4 is encapsulated in test specimen 2 and left metal electrode 1 and right metal electrode 3; The left metal electrode 1 of institute is connected in series respectively by lead-in wire 5 and resistance 8 with right metal electrode 3; The display memory storage 7 of measurement voltage signal is connected in parallel by ground wire 6 and resistance 8.

As the preferred embodiment of the present invention, described left metal electrode 1 and right metal electrode 3 form electrode by the method for evaporation in test specimen left and right surface gold-plating.

As the preferred embodiment of the present invention, described ground wire 6 is connected by the mode of wire bonding with lead-in wire 5 and resistance 8.

As the preferred embodiment of the present invention, described display memory storage 7 is high-speed oscilloscope.

As shown in drawings, the measuring method of measurement mechanism of the present invention, the film flying high velocity impact test specimen 2 of one-stage light-gas gun 9 produces shock compressive wave, there is high strain-rate distortion in test specimen 2, produce strain gradient, produce polarization charge by flexoelectric effect on test specimen about 2 surface again, test specimen about 2 surface charge to be connected with resistance 8 via lead-in wire 5 by left metal electrode 1 and right metal electrode 3 and is formed closed circuit, and the high-speed oscilloscope 7 in parallel with resistance 8 gathers and show pulse voltage signal;

When high speed impact ripple is by test specimen 2, there is high strain-rate distortion, produce the strain gradient of the time that depends on, and strain gradient can produce the polarization displacement of ion; For shock compressive wave, the acceleration of atom is proportional to strain gradient, and the acceleration of the ion of different quality produces extra polarization displacement, thus produces flexure electro dynamic effect, and produce polarization charge, its expression formula is:

$P=(\mathrm{\μ}+{\mathrm{\μ}}_d)\frac{\∂\mathrm{\ϵ}}{\∂x}=\frac{Q}{H^2}$

U＝kQ

Wherein μ _d=-χ cM/ ρ is Dynamic flexural electrostrictive coefficient, and M is the coefficient calculated by lattice dynamics, and ρ is density, and c is elastic constant; μ is static flexoelectric coefficient, ε is the elastic strain of material, x is the direction of gradient, P is the polarization that the strain gradient caused by flexoelectric effect produces, Q is the output charge of two sides, left and right metal electrode, k is electric charges amplify coefficient, and U is the output quantity of magnitude of voltage, and H is the surperficial length of side about material test specimen.Can be found out by formula, directly can measure the pulse voltage of generation.

Claims (5)

1. produce a measurement mechanism for pulse voltage based on flexure electro dynamic effect, it is characterized in that: comprise the left metal electrode (1) and right metal electrode (3) that are separately positioned on test specimen (2) left surface and right surface; Described test specimen (2) and left metal electrode (1) and right metal electrode (3) are encapsulated in epoxy resin (4); Described left metal electrode (1) is connected in series with resistance (8) respectively by go between (5) with right metal electrode (3); Described resistance (8) is connected in parallel by the display memory storage (7) of ground wire (6) with ranging pulse voltage signal.

2. a kind of measurement mechanism producing pulse voltage based on flexure electro dynamic effect according to claim 1, is characterized in that: described left metal electrode (1) and right metal electrode (3) form electrode by the method for evaporation in test specimen left and right surface gold-plating.

3. a kind of measurement mechanism producing pulse voltage based on flexure electro dynamic effect according to claim 1, is characterized in that: described ground wire (6) is connected by the mode of wire bonding with lead-in wire (5) and resistance (8).

4. a kind of measurement mechanism producing pulse voltage based on flexure electro dynamic effect according to claim 1, is characterized in that: the display memory storage (7) of ranging pulse voltage signal is high-speed oscilloscope.

5. the measuring method of the measurement mechanism described in any one of Claims 1-4, it is characterized in that: the film flying high velocity impact test specimen (2) of one-stage light-gas gun (9) produces shock compressive wave, there is high strain-rate distortion in test specimen (2), produce strain gradient, polarization charge is produced on surface, test specimen (2) left and right again by flexoelectric effect, test specimen (2) left and right surface charge to be connected with resistance (8) via go between (5) by left metal electrode (1) and right metal electrode (3) and is formed closed circuit, the high-speed oscilloscope (7) in parallel with resistance (8) gathers and shows pulse voltage signal,

When high speed impact ripple is by test specimen (2), there is high strain-rate distortion, produce the strain gradient of the time that depends on, and strain gradient can produce the polarization displacement of ion; For shock compressive wave, the acceleration of atom is proportional to strain gradient, and the acceleration of the ion of different quality produces extra polarization displacement, thus produces flexure electro dynamic effect, and produce polarization charge, its expression formula is:

$P=(\mathrm{\μ}+{\mathrm{\μ}}_d)\frac{\∂\mathrm{\ϵ}}{\∂x}=\frac{Q}{H^2}$

U＝kQ

Wherein μ _d=-χ cM/ ρ is Dynamic flexural electrostrictive coefficient, and M is the coefficient calculated by lattice dynamics, and ρ is density, and c is elastic constant; μ is static flexoelectric coefficient, ε is the elastic strain of material, x is the direction of gradient, P is the polarization that the strain gradient caused by flexoelectric effect produces, Q is the output charge of two sides, left and right metal electrode, k is electric charges amplify coefficient, and U is the output quantity of magnitude of voltage, and H is the surperficial length of side about material test specimen; The pulse voltage produced directly can be obtained by formula.