CN1015660B - Chock-exciting method of electric eddy-magnetic push-pull and shock exciter - Google Patents

Abstract

The present invention provides a current vortex magnetic push-pull excitation method and a vibration exciter, which is novel no-contact type excitation. The present invention utilizes an alternating magnetic field to induce a test piece to generate inductive current vortex so as to form an induced magnetic field or simultaneously magnetize a magnetic conductive test piece according to electromagnetic induction theory. Therefore, current vortex magnetic push-pull excitation force and electromagnetic push-pull excitation force are formed so as to vibrate the test piece. The vibration exciter has no direct-current magnetic circuit, and is only composed of a vortex inductive head and an excitation coil used for generating the alternating magnetic field. The vibration exciter is not limited by the size and the shape of the test piece in the direction parallel to the end surface of the vortex inductive head. The vibration exciter can be arranged at any position of the test piece, such as the center, edges, etc., and therefore, the vibration exciter is suitable for the excitation of test pieces in the class of infinite wide plates or peripheral fixed plates.

Description

Chock-exciting method of electric eddy-magnetic push-pull and shock exciter

The invention belongs to non-contact electric eddy magnetic and recommend excitation method and vibrator.

Introduce according to " vibrator " joint in " engine strength vibration test technology " (volume such as the Song Zhao of Beijing Aeronaution College is deep, National Defense Industry Press publishes), existing contactless exciting has three kinds of sound wave exciting, electromagnetic exciting and vortex-excited oscillations.The energy of sound wave exciting is little, noise is big; Electromagnetic exciting is only applicable to permeability magnetic material, and frequency response is narrow; Though vortex-excited oscillation has overcome above-mentioned deficiency, it requires test specimen must be finite boundary, or vibrator can only be placed on the edge of test specimen, can not be applied to infinitely wide plate (as aircraft wing, boats and ships housing) or peripheral holding board (as the loudspeaker diaphragm) class test specimen.

The object of the present invention is to provide a kind ofly to be applicable to infinitely wide plate or peripheral holding board class test specimen, and noise is low, frequency response is wide, novel non-contact electric eddy magnetic simple in structure, that can be used for all conductive materials is recommended excitation method and vibrator.

Chock-exciting method of electric eddy-magnetic push-pull involved in the present invention, be to utilize alternating magnetic field to bring out test specimen generation induced electricity eddy current also therefore to form induced field or make the test specimen magnetization simultaneously, electric eddy-magnetic is recommended exciting force and electromagnetism is recommended exciting force thereby form, and makes test specimen vibrate.

If the magnetic induction density of alternating magnetic field is B ₁=B _M1Cos ω t, according to electromagnetic coupling theory, the conduction test specimen can form the induced electricity eddy current under the effect of this alternating flux, and the induced electricity eddy current produces induced field simultaneously.Because of the magnetic flux of induced field is always revolted the flux change (90 ° of its phase lags) of former alternating magnetic field, so the magnetic induction density of induced field is B ₂=B _M2Sin ω t.To produce interaction between alternating magnetic field and induced field, form electric eddy-magnetic and recommend exciting force:

${\mathrm{<figure-callout\; id="1"\; label="F"\; filenames="89105366\_DRIMG1.png"\; state="\{\{state\}\}">F</figure-callout>}}_1=\frac{B_1{B}_2\mathrm{<figure-callout\; id="2"\; label="S"\; filenames="89105366\_DRIMG1.png"\; state="\{\{state\}\}">S</figure-callout>}}{\mathrm{2\; \mu }}\mathrm{=\; Asin2\; \omega \; t\; (N)}$

Wherein: μ _o=4 π * 10 ^-7(H/m)

The face area (m) of S-vortex induction head

The angular frequency of ω-exciting curent (l/S)

Test specimen produces under the effect of this exciting force and is forced to resonance, and vibration frequency is two times of exciting curent frequency.

If test specimen is a permeability magnetic material, then it is also magnetized by alternating magnetic field simultaneously.According to Theory of Electromagnetic Field, the interaction between alternating magnetic field and the test specimen that magnetized forms electromagnetism and recommends exciting force:

${\mathrm{<figure-callout\; id="2"\; label="F"\; filenames="89105366\_DRIMG1.png"\; state="\{\{state\}\}">F</figure-callout>}}_2=\frac{{\mathrm{<figure-callout\; id="1"\; label="B"\; filenames="89105366\_DRIMG1.png"\; state="\{\{state\}\}">B</figure-callout>}}_1{}^2\mathrm{<figure-callout\; id="2"\; label="S"\; filenames="89105366\_DRIMG1.png"\; state="\{\{state\}\}">S</figure-callout>}}{{\mathrm{2\; \mu }}_o}{\mathrm{=\; <figure-callout\; id="2"\; label="Bcos"\; filenames="89105366\_DRIMG1.png"\; state="\{\{state\}\}">Bcos</figure-callout>}}^2\mathrm{\omega \; t\; (N)}$

Therefore effect simultaneously has two exciting forces on the permeability magnetic material test specimen.With F ₂Represent with another kind of form,

That is: F ₂=B(1+cos2 ω t) (N)

Then, according to vector synthesis then, the synthetic result of the harmonic excitation power of two same frequencys is still a harmonic excitation power:

F＝F ₁+F ₂

＝B+C sin（2ωt+φ） （N）

Wherein:

$\mathrm{C\; =}\sqrt{A{}^2\mathrm{+\; <figure-callout\; id="2"\; label="B"\; filenames="89105366\_DRIMG1.png"\; state="\{\{state\}\}">B</figure-callout>}{}^2}$

φ＝tg ^-1（B/A）

Test specimen produces under this force action and is forced to resonance, and vibration frequency also is two times of exciting curent frequency.

Recommend vibrator for realizing the non-contact electric eddy magnetic that above-mentioned excitation method designs, critical piece is the iron-core coil group, only constituted, and need do not contained any in order to produce the member of D.C. magnetic field by vortex induction head and magnetizing coil in order to the generation alternating magnetic field.

Below in conjunction with drawings and Examples the present invention is described in detail.

Accompanying drawing 1. electric eddy-magnetics are recommended the vibrator synoptic diagram.

Wind with magnetizing coil (3) on the vortex induction head (2) (being iron core), be fixed in base (1) then, covering upward again, shell (4) promptly constitutes vibrator of the present invention.It does not have dc circuit magnetic loop, does not have moving component.Base (1) and shell (4) should be insulating material, as textolite, plastics etc.Vortex induction head (2) generally adopts C sections core, and the gap between two magnetic poles is A.Two end faces of vortex induction head should be in the same plane, and concordant with shell (4), like this vibrator to the size of test specimen and shape on the direction parallel with the vortex induction end surface just without limits.Magnetizing coil (3) around opposite to the polarity that should make vortex induction head two magnetic poles.The number of turn of magnetizing coil (3) should be selected on the impedance matching equilibrium running line of vibrator and power amplifier accordingly according to by the vibration measuring frequency range of exciting test specimen.For the benefit of mate, magnetizing coil (3) can adopt a plurality of taps, to realize the Hz-KHz of broad.The placement of test specimen (5) should be parallel with the end face of vortex induction head, promptly when vibrator when placing shown in the accompanying drawing 1, test specimen (5) should flatly place the top of vibrator, is positioned as close to the vortex induction head under the not contacted condition simultaneously when guaranteeing exciting.Vibrator can place any positions such as the center of test specimen or edge.

Feed the simple harmonic quantity exciting curent of frequency adjustable in the magnetizing coil (3), promptly form alternating magnetic field.The magnetic flux of alternation passes test specimen (5), brings out the induced electricity eddy current and therefore produce induced field in test specimen, perhaps makes the magnetization of magnetic conduction test specimen simultaneously, and electric eddy-magnetic is recommended exciting force and electromagnetism is recommended exciting force thereby form.The direction of exciting force is perpendicular to test specimen plate face.Test specimen produces under the effect of exciting force and is forced to resonance.

The effect that electric eddy-magnetic is recommended exciting depends primarily on the impedance matching of distribution, vibrator and power amplifier of current vortex field and physical parameter of test specimen etc.Gap size A between vortex induction head two magnetic poles is the key of textural association, and its best clearance should be between 8～40mm.

The present invention has possessed the following advantage simultaneously:

Vibrator to the size and shape of test specimen on the direction parallel with the vortex induction end surface without limits, vibrator can place any positions such as the center of test specimen or edge, thereby is best suited for the exciting to infinitely wide plate or peripheral holding board class test specimen;

2. can be used for all conduction test specimens (magnetic or nonmagnetic substance all can);

3. low (the own noise of vibrator＜70dB) of noise;

4. Hz-KHz is wide by (10～10000Hz);

5. exciter structure simple (not having dc circuit magnetic loop), thus cost is low, volume is little, in light weight, working service convenient.

Claims (3)

1, a kind of non-contact electric eddy magnetic is recommended excitation method, utilize vibrator to make the test specimen vibration, vibrator does not contact with test specimen, produce exciting force by electromagnetic action, exciting force directly acts on test specimen, the direction of exciting force is perpendicular to test specimen plate face, test specimen produces under the effect of exciting force and is forced to resonance, it is characterized in that vibrator and the parallel placement of test specimen plate face, the end face that is vortex induction head in the vibrator is parallel to test specimen plate face, the simple harmonic current of giving logical adjustable frequency in the magnetizing coil of vibrator is to form alternating magnetic field, this alternating flux is brought out the induced electricity eddy current and is therefore formed induced field in test specimen, perhaps make the magnetization of magnetic conduction test specimen simultaneously, electric eddy-magnetic is recommended exciting force and electromagnetism is recommended exciting force thereby form.

2, a kind of non-contact electric eddy magnetic is recommended vibrator, constitute by the iron-core coil group, it is characterized in that iron core is a C sections core, opening is fixed in base up, the both ends of the surface of iron core are in the same plane, and the magnetizing coil of the simple harmonic quantity exciting curent of logical adjustable frequency is in the opposite direction around the both sides of iron core.

3, vibrator as claimed in claim 2 is characterized in that the gap A between two magnetic poles of iron core has an optimum range, is 8～40mm.

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