CN104374468B - A kind of slender body intrinsic frequency measuring method - Google Patents

A kind of slender body intrinsic frequency measuring method Download PDF

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CN104374468B
CN104374468B CN201410577405.1A CN201410577405A CN104374468B CN 104374468 B CN104374468 B CN 104374468B CN 201410577405 A CN201410577405 A CN 201410577405A CN 104374468 B CN104374468 B CN 104374468B
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signal
intrinsic frequency
frequency
measurement
mrow
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CN201410577405.1A
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CN104374468A (en
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张东来
周智慧
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哈尔滨工业大学深圳研究生院
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Abstract

The present invention proposes a kind of method of intrinsic frequency measurement, can be widely applied to the intrinsic frequency detection for the structure that the magnetic conductions such as pipeline, anchor pole, steel wire rope, suspension cable, sheet material, tank body or non-magnetic material are formed.The present invention realizes contact or contactless excitation and the detection of vibration signal using sensor according to magnetostrictive effect with counter magnetostriction effect, obtains system frequency response functionH a,b (f) corresponding to Fourier spectrum distribution curve, wherein,aFor measurement point,bTo encourage point, it is determined thatH a,b (f) corresponding to peak point in Fourier spectrum distribution curve, so as to obtain the intrinsic frequency of system.The method of the present invention not only allows for contact type measurement, also allows the lift-off distance between larger sensor and measured object, also detectable fainter vibration signal, has broad application prospects in intrinsic frequency measurement.

Description

A kind of slender body intrinsic frequency measuring method
Technical field
The invention belongs to field of non destructive testing, more particularly to a kind of method for measuring intrinsic frequency.
Background technology
Pipeline, tank body etc. are important fluid transport media, have been widely used in the transport of oil, natural gas and water etc. In;Steel wire rope, anchor pole, suspension cable etc. are important load bearing components, in the cable-stayed bridge that has been widely used, drilling platforms.However, work as The components such as pipeline, steel wire rope by outside wind load, be transported outside fluid oscillation etc. continue exciting force effect when, once exciting force frequency Rate is close with its intrinsic frequency, can cause fluid that coupled resonance occurs with structure, and the stress of material internal easily reaches strength degree, So as to cause the destruction of material, its service life is reduced.Therefore, to improve the security of structure operation, extraneous exciting force is avoided Destruction, the measurement of the resonance characteristics of structure just seems extremely important.
To obtain its resonance characteristics, its intrinsic frequency need to be measured.Traditional intrinsic frequency measuring method is general to use hammer Hit, air bubble, laser ablation or piezoelectric transducer exciting, and leading of being propagated in structure is detected using piezoelectric acceleration sensor Ripple signal;But these methods are contact encourages and detection method, do not allow to have between sensor and measured object it is larger between Away from, this for the pipeline with external coating, outer surface out-of-flatness the measured object such as steel wire rope for, above-mentioned contact excitation and inspection Survey method does not apply to.Meanwhile above-mentioned contaction measurement method also has one disadvantage in that, i.e., included simultaneously in the vibration signal because caused by Compressional wave and shear wave, causes the intrinsic frequency that corresponding compressional wave or shear wave are difficult to differentiate between out according to detection signal.
The content of the invention
In order to solve problem in the prior art, it is intrinsic that the present invention proposes a kind of measurement structure for sampling magnetostriction principle The method of frequency, method of the invention not only allow for contact type measurement, also allow carrying between larger sensor and measured object Separation is from application scenario of the invention is not limited to the pipeline of circular cylindrical shell structure, can also be applied to bar, steel wire rope, oblique pull The intrinsic frequency detection of the structure of the magnetic conductions such as rope, sheet material, tank body or non-magnet material.
The present invention is achieved through the following technical solutions:
A kind of method of measurement structure intrinsic frequency, applied to intrinsic frequency measuring apparatus, the measuring apparatus includes letter Number module, power amplifier, current detection module, signal conditioning circuit, signal acquisition module, data analysis module and biography occurs Sensor;Methods described allows sensor and measured object surface to have a certain distance, the sensor according to magnetostrictive effect with Counter magnetostriction effect realizes the excitation and detection of vibration signal, the described method comprises the following steps:
Step 1:The sensor is set in measurand to produce the bias magnetic field H needed for vibration;
Step 2:The model of measurand and sensor is established, excitation is calculated and is shaken with detecting compressional wave, bending wave or torsional wave etc. DC bias magnetic field H under dynamic form needed for corresponding sensor and its magnetic line of force distribution in measurand, according to biasing Magnetic field H distribution, it is determined that being detected using intrinsic frequency corresponding to the progress of the vibration modes such as compressional wave, bending wave, shearing wave or torsional wave When required magnet exciting coil and detection coil winding method and the correct position in bias magnetic field;
Step 3:Row energization is entered to magnet exciting coil with exciting current i (t), to produce the more single guided wave of vibration mode;
Step 4:The voltage signal V (t) that guided wave is corresponded under corresponding vibration mode is obtained by detection coil;
Step 5:Exciting current signal i (t) is gathered by current detection module, by the number together with detection signal V (t) Analyzed according to analysis module, to obtain system frequency response function Ha,b(f) Fourier spectrum distribution curve corresponding to, wherein, a is Measurement point, b are excitation point;
Step 6:Determine Ha,b(f) peak point in Fourier spectrum distribution curve corresponding to, so as to obtain the intrinsic of system Frequency.
Further, the measuring apparatus specifically includes:
Signal generating module:Using microcontroller mode, generation trigger signal collection mould are combined with signal generating circuit The pulse signal of block and export wide spectrum pulse excitation signal to power amplifier;
Power amplifier:It is made up of operational amplifier and power device, to generate exciting current i (t);
Sensor:Including stimulus sensor and detection sensor, it is made up of respectively bias magnetic field and coil, wherein biasing magnetic By yoke, set of permanent magnets into magnetizer produce, the polarity of the magnetic field of permanent magnet is according to required excitation and the vibration mode detected Guided wave selection;Several required magnetizers can be used to produce the bias magnetic field of needs on one detected object.
Signal conditioning circuit:The voltage signal V of detection coil sensor output1(t), this voltage signal circuit after filtering Afterwards, amplify by differential amplifier circuit, then put by the linear amplifier circuit of a low maladjustment voltage, low excursion with temperature and low noise Greatly, so as to obtaining the final output voltage signal V of signal conditioning circuit2(t);
Signal acquisition module:Signal acquisition module gathers the voltage signal V of signal conditioning circuit with higher sample frequency2 (t) it is final to obtain repeated detection and make the detectable voltage signals V (t) after multiple averaging and i (t) with exciting current i (t);
Data analysis module:According to detectable voltage signals V (t) and i (t), the frequency response function H of calculating acquisition systema,b (f) the curve after Fourier transformation, and then according to Peak Intensity Method, intrinsic frequency corresponding to acquisition.
Further, according to bias magnetic field H distribution, determine that magnet exciting coil and detection coil are suitable in bias magnetic field Position is specially:Establish the model comprising sensor and measurand, according to model parameter, it is calculated needed for excitation with The magnetic line of force distribution of the bias magnetic field needed under the vibration mode of detection, then magnetic line of force distribution is calculated according to magnetic line of force distribution Change curve, and the demand according to the single vibration that need to be encouraged and detect to bias magnetic field further determines that coil can be placed More accurate suitable position.
The beneficial effects of the invention are as follows:The method of measurement structure intrinsic frequency provided by the invention can not only realize contact Measurement, the non-contact measurement of system frequency can be also carried out, measuring method is better than traditional contact measurement method, can be right The magnetic conductions such as band external anti-corrosion layer pipeline, bar structure, shell structure or non-magnet material realize natural frequency measurement,.To non-magnet material Structure measurement when, be adhered to the tested of sensor position using the material tight with high-magnetostriction coefficient of magnetic conduction On object, the coupling transmission of corresponding vibration mode guided wave is realized by high-magnetostriction coefficient material, so as to be imitated according to magnetostriction This technology should can be used to realize that tested non-magnet material intrinsic frequency measures with magnetostrictive reaction.Measurement result is accurate, Can solve traditional contact inherent frequency detection method to be difficult in the pipeline with external anti-corrosion layer, outer surface out-of-flatness steel wire rope etc. The problem of being applied in measured object, it can be widely applied to the magnetic conductions such as common pipe, the pipeline with anticorrosive coat, steel wire rope, sheet metal Or the intrinsic frequency detection of the structure of non-magnet material.
Brief description of the drawings
Fig. 1 is a tested pipeline Natural Frequency of Longitudinal Vibration measuring apparatus connection diagram;
Fig. 2 is sensor two dimensional model figure;
Fig. 3 is the two-dimentional distribution diagram of magnetic line of force of the bias magnetic field of magnetizer generation;
Fig. 4 is the transverse direction magnetic induction density B in some positions yyRelation schematic diagram between x;
Fig. 5 is the axial direction magnetic induction density B in some positions xxRelation schematic diagram between y;
Fig. 6 is a kind of division schematic diagram of intrinsic frequency test point of a tested pipeline;
Fig. 7 is an exciting current oscillogram with broad spectrum;
Fig. 8 is one, and there is the exciting current waveform of broad spectrum to detect obtained multiple averaging at 3 points after 8 points of excitations Voltage signal V (t) schematic diagrames afterwards;
Fig. 9 is that the amplitude versus frequency characte after the Fourier transformation for the system frequency response function that sensor forms with tested pipeline is exhausted To being worth curve map;
Figure 10 is amplitude versus frequency characte absolute value curve after the Fourier transformation of system frequency response function in 0~10kHz Enlarged drawing.
Embodiment
The present invention is further described for explanation and embodiment below in conjunction with the accompanying drawings.
As shown in Figure 1 be tested pipeline Natural Frequency of Longitudinal Vibration measuring apparatus of the present invention, its Middle N and S represents the two poles of the earth of bias magnetic field respectively, and N is N poles, and S is S poles;The equipment is included with lower module:
Signal generating module:Using microcontroller mode, generation trigger signal collection mould are combined with signal generating circuit The pulse signal of block and export wide spectrum pulse excitation signal to power amplifier;
Power amplifier:It is made up of operational amplifier and power device, to generate exciting current i (t);
Sensor:Including stimulus sensor and detection sensor, it is made up of respectively bias magnetic field and coil, wherein biasing magnetic By yoke, set of permanent magnets into magnetizer produce, the polarity of the magnetic field of permanent magnet is according to required excitation and the vibration mode detected Guided wave selection;Several required magnetizers can be used to produce the bias magnetic field of needs on one detected object.
Current detection module:Exciting current is gathered, obtains exciting current signal i (t).
Signal conditioning circuit:The voltage signal V of detection coil sensor output1(t), this voltage signal circuit after filtering Afterwards, amplify by differential amplifier circuit, then put by the linear amplifier circuit of a low maladjustment voltage, low excursion with temperature and low noise Greatly, so as to obtaining the final output voltage signal V of signal conditioning circuit2(t);
Signal acquisition module:Signal acquisition module gathers the voltage signal V of signal conditioning circuit with higher sample frequency2 (t) it is final to obtain repeated detection and make the detectable voltage signals V (t) after multiple averaging and i (t) with exciting current i (t);
Data analysis module:According to detectable voltage signals V (t) and i (t), the frequency response function H of calculating acquisition systema,b (f) the curve after Fourier transformation, and then according to Peak Intensity Method, intrinsic frequency corresponding to acquisition.
Magnetostriction realizes that the non-contact excitation of the intrinsic frequency of pipeline and detection basic procedure are:Produced when by signal generator After a raw excitation pulse signal, excitation pulse signal is exported to power amplifier, so as to which power amplifier is according to excitation arteries and veins One wide spectrum drive pulse current i (t) of signal output is rushed to the coil in sensor.Pulse current i (t) acts on coil simultaneously Excitation field H (t) is produced on pipeline is detected, excitation field H (t) will be with DC bias magnetic field H0Collective effect is in measured tube On road, so as to which vibration will be produced in tested pipeline based on magnetostrictive effect.Caused vibration signal can be recognized in tested pipeline To be the guided wave propagated in tested pipeline.When guided wave is along pipe transmmision, based on counter magnetostriction effect, magnetostriction passes Sensor will detect voltage signal V (t).Because bias magnetic field size is typically designed as on measured material magnetization curve BH curve Corresponding moderate magnetic field, then in the range of linear magnetostriction, according to magnetostrictive effect and the general principle of converse magnetostriction, Magnetostriction deformation ε is regarded as being proportional to exciting current i (t), and detectable voltage signals V (t) is it is believed that be proportional to magnetostriction The rate of change of deformationHerein it is assumed that the system of stimulus sensor, detection sensor, pipeline composition is a linear system System.When detecting extensional vibration, according to the exciting current i (t) detected and extensional vibration voltage signal V (t), can be calculated The frequency response function of system is:
Wherein I (f) |aFor the exciting current i (t) of a points Fourier transformation, V (f) |bFor the voltage signal V detected in b points (t) Fourier transformation, ω g are angular frequency, and k is coefficient, and hereinFinally, tested according to intrinsic frequency Peak Intensity Method, the intrinsic frequency point of corresponding pipeline configuration can be obtained.To obtain higher Signal-to-Noise and intrinsic frequency point Resolution, here, using higher signal sampling frequencies, and using repeatedly excitation and detection mode.And signal is repeatedly put down , to improve signal to noise ratio.
Method effect to illustrate the invention, the present invention select a specific embodiment in its application scenario to come to this hair Bright method illustrates.
To a length 3000mm, density 7850kg/m3, Young's modulus 210Gpa, there are two that plastic bushing surrounds outside The pipeline of free support is held to carry out the non-cpntact measurement of Natural Frequency of Longitudinal Vibration.To realize the excitation of single longitudinal vibrations form With detection, the position of coil needs to be carefully selected according to the distribution of bias magnetic field.
Under longitudinal vibrations form, because steel pipe is axisymmetric structure, to obtain the magnetic line of force after bias magnetic field excitation Distribution, by known pipe parameter and sensor parameters, build herein by steel pipe, air, sensor group into two dimensional model, such as Shown in accompanying drawing 2.And the rectangular coordinate system using sensor center position as the origin of coordinates is established, magnetic line of force distribution is carried out to it and is carried out Calculate, and the magnetic line of force distribution curve obtained is as shown in Figure 3.
To determine the position suitably placed of coil, with reference to the accompanying drawings 3, the magnetic induction density B along Y direction is calculatedyIt is right Should be in the curve at different x positions, as shown in Figure 4;With reference to the accompanying drawings 3, the magnetic induction density B along X-direction is calculatedxIt is right Should be in the curve at different y locations, as shown in Figure 5.
4 understood with reference to the accompanying drawings with accompanying drawing 5, when coil is enclosed in the outer surface of plastic conduit, by x=x0To x=x1With line Y=y0To line y=y1Magnetic induction density B in the closed area of compositionyValue hardly produces shadow to encouraging and detecting compressional wave Ring, this closed area is simultaneously shown in Figure 2;Meanwhile the magnetic induction density B of these opening positions verticallyxDirection is constant, Same direction axially, so as to only be contributed to excitation and detection compressional wave.Therefore, can with reference to the accompanying drawings 4 with the magnetic of accompanying drawing 5 The analysis result of field intensity distribution, determines that the position of coil can be placed in the range of this, within this range, X-direction vertically Axial magnetic induction density BxMagnetic direction is consistent and distribution is more uniform, while along the magnetic field intensity B of Y directionyIt is small, so as to Encourage and detect the guided wave of the more single extensional vibration of mode.
To test the intrinsic frequency of pipeline, pipeline is evenly dividing test point, a kind of signal of the dividing mode of test point Figure is as shown in Figure 6.Because of the symmetry of pipeline geometry, frequency response function Ha,b(f)=Hb,a(f), it is meant that excitation point It can be exchanged with test point, to facilitate test.Because the guided wave that gone directly at 7 points, caused by excitation easily draws electricity with exciting current Magnetic induction signal overlap, so, while encouraging for 8 points, detected in 1 to 6 point, i.e. a=8, b=1,2,3 ..., 6.Survey Pilot schematic diagram is as shown in Figure 6.
Exciting current waveform i (t) examples are as shown in Figure 7 used by this specific embodiment.The exciting current is wideband The drive pulse current exciting current of spectrum, amplitude and narrow spaces.The exciting current at interval of export for a period of time to excitation pass Coil in sensor, guided wave is generated, and sample the voltage signal received in one section of long period that sensor detects.Receive and pass The voltage signal detected of sensor is by low-pass filter circuit, differential linearity voltage amplifier circuit and with extremely low noise, low Offset voltage, low excursion with temperature characteristic linear voltage amplifying circuit after by data collecting module collected, then in data acquisition In module collection to multiple repairing weld to voltage signal carry out summation and average, so as to obtain the detection voltage of high s/n ratio letter Number V (t), here, providing the voltage signal V (t) of a detection at 3 points, as shown in Figure 8.
The amplitude spectrum after Fourier transformation of the exciting current with detecting voltage is calculated successively, according to formula (1), can obtain Amplitude versus frequency characte absolute value curve after the Fourier transformation of system frequency response function is as shown in Figure 9.To the 0 of accompanying drawing 9~ Amplitude versus frequency characte absolute value curve magnification figure after the Fourier transformation of 10kHz system frequency response function is such as the institute of accompanying drawing 10 Show.
Peak Intensity Method (being mark referring to the circle added in accompanying drawing 10) is used to the waveform of accompanying drawing 10, pipeline configuration can be obtained Intrinsic frequency it is as shown in table 1.
The intrinsic frequency measured value f that will be measured according to Peak Intensity Methodmea, with the value according to Euler-Bernoulli theoretical calculations fcalBetween difference be defined as absolute error, fmeaWith fcalRatio be defined as:
K=fmea/fcal (2)
K is the ratio between the intrinsic frequency measured value and theoretical value obtained according to Peak Intensity Method in formula (2).
Table 1 gives the natural frequency value and calculated value in the 10kHz of the actual measurement at 3 points, and provides measured value and reason By the error and ratio between calculated value.
The intrinsic frequency measured value of extensional vibration in the 10kHz of table 1 is compared with theoretical value
As a result show, the non-contact measurement of system frequency is carried out better than tradition using this intrinsic frequency measuring method Contact measurement method, can be to realizing the non-cpntact measurement of intrinsic frequency with external anti-corrosion layer pipeline, measurement result is accurate, can solve Certainly traditional contact inherent frequency detection method is difficult to tested in the pipeline with external anti-corrosion layer, outer surface out-of-flatness steel wire rope etc. The problem of being applied in thing.
Intrinsic frequency detection to pipeline is only the particular application of the present invention, when to pipeline compressional wave, bending wave When intrinsic frequency detects, coil can bypass the outer peripheral face of pipeline configuration;But corresponding under other vibration modes such as pipeline torsional wave When intrinsic frequency detects, coil is the coil of planarized structure, it is not necessary to which pipeline is surrounded;And these three vibration modes Bias magnetic field it is also different.In addition, when for the isostructural detection of plate, tank body, coil is the coil of planarized structure, Also structure need not be surrounded.
Above content is to combine specific preferred embodiment further description made for the present invention, it is impossible to is assert The specific implementation of the present invention is confined to these explanations.For general technical staff of the technical field of the invention, On the premise of not departing from present inventive concept, some simple deduction or replace can also be made, should all be considered as belonging to the present invention's Protection domain.

Claims (11)

1. a kind of method for measuring slender body intrinsic frequency, methods described is applied to be set by what the intrinsic frequency of geodesic structure measured Standby, the measuring apparatus includes signal generating module, power amplifier, current detection module, signal conditioning circuit, signal acquisition Module, data analysis module and sensor;The sensor is realized according to magnetostrictive effect with counter magnetostriction effect to be vibrated The contact of signal or contactless excitation and detection, it is characterised in that:It the described method comprises the following steps:
Step 1:The sensor is set in measurand to produce the bias magnetic field H needed for vibration;
Step 2:The model of measurand and sensor is established, calculating needs to encourage and corresponding sensing under the vibration mode detected DC bias magnetic field H needed for device and its magnetic line of force distribution in measurand, according to bias magnetic field H distribution, it is determined that adopting Corresponding to corresponding vibration mode is carried out intrinsic frequency detect when required magnet exciting coil and detection coil winding method with And the correct position in bias magnetic field;
Step 3:Row energization is entered to magnet exciting coil with exciting current signal i (t), to produce the more single guided wave of vibration mode;
Step 4:The voltage signal V (t) that guided wave is corresponded under corresponding vibration mode is obtained by detection coil;
Step 5:Exciting current signal i (t) is gathered by current detection module, by the data point together with voltage signal V (t) Module analysis is analysed, to obtain system frequency response function Ha,b(f) Fourier spectrum distribution curve corresponding to, wherein, a is excitation Point, b are measurement point;
Step 6:Determine Ha,b(f) peak point in Fourier spectrum distribution curve corresponding to, so as to obtain the intrinsic frequency of system Rate.
2. the method for measurement slender body intrinsic frequency according to claim 1, it is characterised in that:The measuring apparatus tool Body includes:
Signal generating module:Mode is combined with signal generating circuit using microcontroller, generation trigger signal acquisition module Pulse signal and export wide spectrum pulse excitation signal to power amplifier;
Power amplifier:It is made up of operational amplifier and power device, to generate exciting current signal i (t);
Sensor:Including stimulus sensor and detection sensor, be made up of respectively bias magnetic field and coil, wherein bias magnetic field by Yoke, set of permanent magnets into magnetizer produce, the polarity of the magnetic field of permanent magnet being led according to required excitation and the vibration mode detected Ripple selects;Several required magnetizers can be used to produce the bias magnetic field of needs on one detected object;
Current detection module:Exciting current is gathered, obtains exciting current signal i (t);
Signal conditioning circuit:Detect the voltage signal V of the sensor output1(t), this voltage signal is after filtering after circuit, warp Differential amplifier circuit amplification is crossed, then is amplified by the linear amplifier circuit of a low maladjustment voltage, low excursion with temperature and low noise, from And obtain the final output voltage signal V of signal conditioning circuit2(t);
Signal acquisition module:Signal acquisition module gathers the voltage signal V of signal conditioning circuit with higher sample frequency2(t) with Exciting current signal i (t), it is final to obtain repeated detection and make the voltage signal V (t) after multiple averaging and i (t);
Data analysis module:According to voltage signal V (t) and i (t), the frequency response function H of calculating acquisition systema,b(f) Fu In curve after leaf transformation, and then according to Peak Intensity Method, intrinsic frequency corresponding to acquisition.
3. the method for measurement slender body intrinsic frequency according to claim 1, it is characterised in that:The vibration mode bag Include compressional wave, bending wave, shearing wave or torsional wave.
4. the method for measurement slender body intrinsic frequency according to claim 1, it is characterised in that:According to bias magnetic field H Distribution, determine that the correct position of magnet exciting coil and detection coil in bias magnetic field is specially:Foundation includes sensor and quilt The model of object is surveyed, according to model parameter, it is calculated required excitation and the biasing magnetic needed under the vibration mode of detection Magnetic line of force distribution, then the change curve of magnetic line of force distribution is calculated according to magnetic line of force distribution, and according to need to encourage and examine The single vibration of survey further determines that the more accurate suitable position that coil can be placed to the demand of bias magnetic field.
5. the method for measurement slender body intrinsic frequency according to claim 4, it is characterised in that:The coil is placed on Near measurand, the position that coil can be placed is to calculate encouraging and examining for determination according to sensor and the model of measurand The region of the single vibration form of survey.
6. the method for measurement slender body intrinsic frequency according to claim 1, it is characterised in that:The exciting current letter Number i (t) is the exciting current of wide spectrum, amplitude and narrow spaces.
7. the method for measurement slender body intrinsic frequency according to claim 1, it is characterised in that:The system frequency is rung Answer function Ha,b(f) according to the amplitude spectrum after the Fourier transformation of the voltage signal V (t) after multiple averaging and exciting current signal i (t) Fourier transformation amplitude spectrum, which calculates, to be obtained;The system frequency response function Ha,b(f) it is:
<mrow> <msub> <mi>H</mi> <mrow> <mi>a</mi> <mo>,</mo> <mi>b</mi> </mrow> </msub> <mrow> <mo>(</mo> <mi>f</mi> <mo>)</mo> </mrow> <mo>=</mo> <mfrac> <mrow> <mi>V</mi> <mrow> <mo>(</mo> <mi>f</mi> <mo>)</mo> </mrow> <msub> <mo>|</mo> <mi>b</mi> </msub> </mrow> <mrow> <msub> <mi>jk&amp;omega;</mi> <mi>g</mi> </msub> <mo>&amp;CenterDot;</mo> <mi>I</mi> <mrow> <mo>(</mo> <mi>f</mi> <mo>)</mo> </mrow> <msub> <mo>|</mo> <mi>a</mi> </msub> </mrow> </mfrac> <mo>,</mo> </mrow>
Wherein, I (f) |aFor the exciting current signal i (t) of a points Fourier transformation, V (f) |bFor the voltage signal detected in b points V (t) Fourier transformation, ωgFor angular frequency, k is coefficient, and herein
8. the method for measurement slender body intrinsic frequency according to claim 1, it is characterised in that:The bias magnetic field H Produced by permanent magnet or the coil of energization.
9. the method for measurement slender body intrinsic frequency according to claim 1, it is characterised in that:The intrinsic frequency of measurement The method of rate can be applied to the intrinsic frequency detection of magnetic conduction or non-magnetic material.
10. the method for measurement slender body intrinsic frequency according to claim 1, it is characterised in that:The measurement is intrinsic The method of frequency can be applied to the intrinsic frequency detection of shell structure, suspension cable, plate construction, tank structure.
11. the method for measurement slender body intrinsic frequency according to claim 1, it is characterised in that:The measurement is intrinsic The method of frequency can be applied to pipe, bar structure, the intrinsic frequency of steel wire rope detect.
CN201410577405.1A 2014-10-24 2014-10-24 A kind of slender body intrinsic frequency measuring method CN104374468B (en)

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CN104792404B (en) * 2015-04-22 2018-09-25 华中科技大学 A kind of pipeline natural frequency measurement, method and measuring system
CN104849147A (en) * 2015-05-26 2015-08-19 山东交通学院 Modal natural frequency-based metal material Young modulus measurement device and method
CN105583203B (en) * 2016-01-21 2018-12-28 燕山大学 The magneto vibration descaling and antiscaling device and driving frequency calculation method of magnetic conduction pipe conveying fluid
CN107860465B (en) * 2017-10-12 2021-03-16 哈尔滨工业大学(深圳) Method for detecting inherent frequency of magnetostrictive guided wave longitudinal wave pipeline
CN109187752A (en) * 2018-10-11 2019-01-11 哈尔滨工业大学(深圳) Detect the magnetostrictive guided-wave sensor and its detection method of elevator traction steel band
CN110146249A (en) * 2019-04-26 2019-08-20 河海大学 A kind of pressure-measuring pipe road optimum design method for wind tunnel test

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CN1183142A (en) * 1995-03-09 1998-05-27 西南研究院 Non-destructive evaluaion of pipes and tubes using magnetostrictive sensors
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