CN102818686B - Grid-control TWT metal grid mesh Modal Experimental Method - Google Patents
Grid-control TWT metal grid mesh Modal Experimental Method Download PDFInfo
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Abstract
The invention discloses a kind of grid-control TWT metal grid mesh Modal Experimental Method, the method for employing pointwise excitation that it comprises the steps: (1), single-point pick-up, measuring point arranged by aperture plate test specimen; (2) with hammering method to wire-grid structure with exciting, measure simultaneously its response; (3) signal obtained is inputted computing machine after A/D converter is sampled, calculate the transport function of point of excitation and response point, obtain the frequency of aperture plate; (4) by the method for acoustic wave excitation, entirety excitation is carried out to wire-grid structure, measure the response of each point with laser vibration measurer, and the matching carrying out transfer curve in real time in computing machine obtains the Mode Shape of aperture plate.
Description
Technical field
The present invention relates to travelling-wave tube, particularly relate to a kind of grid-control TWT metal grid mesh Modal Experimental Method.
Background technology
Travelling-wave tube is one of widely used most important electron device.Some environment for use very severes of travelling-wave tube, need to have very strong anti-vibration, impact property.In order to verify the resistance to shock of travelling-wave tube, need to carry out vibration test to travelling-wave tube, and modal test is the basis of other vibration testing analysis, in modal test, detect that the modal parameter (eigenfrequncies and vibration models) of product bears the important parameter in dynamic load structural design.
Modal test domestic is at present only for some Large Scale Mechanical Structures, as aircraft, automobile, boats and ships, bridge and building etc., the structure of travelling-wave tube is generally the microstructure of more complicated, and its sealing characteristics also makes inner modal parameter cannot by finished product direct-detection.More domestic units also obtain the modal parameter of travelling-wave tube microstructure inside by means of only the method for computer simulation emulation at present, and the mode verification system of complete set does not verify the accuracy of its analog result.
Travelling-wave tube internal part structure is more very complicated and small, and if spoke-like aperture plate is the weak element lost efficacy because of vibration in travelling-wave tube, the dynamics of this light and soft microstructure has become the important directions of travelling-wave tube stability and reliability consideration.With regard to kinetic theory research, mainly also depend on numerical simulation at present, also there is no the test method analyzed for kinetic theory characteristic parameter of set of system so far.
Summary of the invention
For the shortcoming of prior art, the object of this invention is to provide a kind of grid-control TWT metal grid mesh Modal Experimental Method, for detecting the modal parameter of microstructure electronic product, grasp the kinematic behavior of its structure, check its resistance to shock, solve the microstructure of this kind of vacuum electron device of travelling-wave tube---a mode checking difficult problem for spoke-like metal grid mesh.
To achieve these goals, technical scheme of the present invention is: a kind of grid-control TWT metal grid mesh Modal Experimental Method, and the method for employing pointwise excitation that it comprises the steps: (1), single-point pick-up, measuring point arranged by aperture plate test specimen; (2) with hammering method to wire-grid structure with exciting, measure simultaneously its response; (3) signal obtained is inputted computing machine after A/D converter is sampled, calculate the transport function of point of excitation and response point, obtain the frequency of aperture plate; (4) by the method for acoustic wave excitation, entirety excitation is carried out to wire-grid structure, measure the response of each point with laser vibration measurer, and the matching carrying out transfer curve in real time in computing machine obtains the Mode Shape of aperture plate.
Further, in step (1), the shell of aperture plate is arranged 68 measuring points altogether, form the network of aperture plate.
Further, aperture plate is fixed on the fixture of boring, consistent with physical constraint.
Preferably, described fixture adopt good rigidly, weight low, there is higher rigid mass ratio and the aluminum alloy materials of high damping characteristic, fixture whole block material processes, the center of gravity of fixture and test product with test table top center superposition.
Compared with prior art, the present invention adopts hammering determination natural frequency, and the motivational techniques of the acoustically-driven determination vibration shape solve the microstructure problem that exciting does not get up because frequency is too high; Aperture plate is adopted to be fixed on the fixture of boring, the structure support method consistent with physical constraint.Solve microstructure---the installation of travelling-wave tube aperture plate and the problem of location; Adopt laser beam to replace traditional sensor, method, gather vibration response signal on aperture plate, solve size because of microstructure too little, cannot Surface Mount sensor and the difficult problem of settling signal detection cannot be obtained.
Accompanying drawing explanation
Below in conjunction with accompanying drawing, the present invention is described in further detail.
Fig. 1 is pilot system schematic diagram.
Fig. 2 is travelling-wave tube aperture plate test specimen figure.
Fig. 3 is aperture plate modal test installation drawing.
Fig. 4 is wire-grid structure modal test system diagram.
Fig. 5 is aperture plate model vibration point layout figure.
Fig. 6 is oscillating curve and the spectrogram of aperture plate.
Fig. 7 is the spectrogram of aperture plate under single-frequency sound wave excitation.
Fig. 8 is the modal test bending vibation mode picture of aperture plate.
Fig. 9 is aperture plate simulation result figure.
Embodiment
The present invention adopts frequency domain identification method to carry out the test modal analysis of the shell structure to aperture plate.Employing pointwise encourages, the method of single-point pick-up, aperture plate test specimen arranges 68 measuring points, with hammering method to wire-grid structure with exciting, measure its response, then signal is inputted computing machine after A/D converter is sampled, these data convert through quick Fourier (FFT) simultaneously, then calculate the transport function of point of excitation and response point, obtain the frequency of aperture plate.Then by the method for acoustic wave excitation, entirety excitation is carried out to wire-grid structure, measure the response of each point with laser vibration measurer, and the matching carrying out transfer curve in real time in computing machine obtains the Mode Shape of aperture plate.Modal Test method is a kind of test method of direct measuring system eigenfrequncies and vibration models, it passes through input signal and the output signal of measuring system simultaneously, according to testing the transfer curve recorded, carry out curve fitting, thus calculate natural frequency, modal stiffness, modal mass etc.In practical structures or shaking table test, show that the natural frequency of vibration of structure is the object of many tests, the natural frequency of vibration measuring structure with hammering method is a kind of both economical, desirable vibration measuring method, this method can realize multi-point exciting (firmly hammer knocks multiple spot) and single-point response, show hammering frequency response curve in real time on computers, go out the transport function of each hammering vibration measuring point, auto-power spectrum, cross-power spectrum, coherence function and fourier spectra by multiple stacking average computation.In travelling-wave tube spoke-like aperture plate microstructure modal test verification technique, for this special construction of aperture plate---arch engraved structure, quality are light and soft, cannot sensor be mounted, its vibration experiment build key issues such as mainly solving motivational techniques, signals collecting and structure support.
Refer to Fig. 1 and Fig. 4, the test macro of vibration test is made up of three parts: (1) excitation system.Excitation system mainly comprises vibrator, completes the excitation to test specimen by it.Typical exciting bank has exciter system, ram hammer, step excitation device.Energisation mode has single-point-excitation, excitation and single-point partition excitation.The power hammer adopted in test and acoustic wave excitation two kinds of energisation modes.(2) measure portion.Measure portion is data acquisition mainly, comprises sensor, charge amplifier and relevant coupling part.Its function is that measured (power and response acceleration) is become electric signal by sensor transformation, and then after charge amplifier or decay, entering signal analysis software disposal system processes.Due to the special construction of aperture plate, replace acceleration transducer by laser beam, gather vibration response signal on aperture plate, measure the deformation quantity of aperture plate reference point.PSV-300 laser scanning system is adopted to carry out structure modal test to aperture plate in test.First after being made a video recording by aperture plate by the minisize pick-up head of laser head inside, figure reached computing machine and carry out layouting before scanning test, after starting collector, laser by the automatic data acquisition carrying out scan test and measuring point by scanning sequency, and carries out frequency response function analyzing and processing in real time in computing machine.Test obtains first three rank natural frequency of structure and calculated value closely, and maximum measurement relative error is 3.5%.(3) signal processing system.Analysis part mainly comprises the peripherals such as analyser and microcomputer (software package), printer.The effect of analyser is measured and analyzes the signal produced by sensor or laser instrument, until obtain transfer function data, it take fast fourier transform (FFT) technology as the Digital Signal Analysis system of core.
Refer to Fig. 3, the fixture of test is one is the custom-designed test fixture of aperture plate microstructure modal test, and its supporting way is consistent with the actual welding situation of aperture plate in travelling-wave tube rifle body.Its adopt good rigidly, weight low, there is higher rigid mass ratio and the aluminum alloy materials of high damping characteristic; Fixture whole block material processes, and eliminates the self-sustained oscillation of fixture; All surface of contact reach required flatness to ensure good Mechanical Contact, and ensure the center of gravity of fixture and test product and test table top center superposition.
Refer to Fig. 5, in order to reflect the dynamic perfromance of aperture plate comprehensively, consider the feature of its structure simultaneously, 68 measuring points are arranged altogether at the hole Nodes of aperture plate shell, to be formed in the network test of aperture plate first by laser head inside minisize pick-up head will aperture plate make a video recording after figure reached computing machine and the test carrying out scanning test is layouted, after starting collector, laser will carry out scan test and data acquisition by scanning sequency automatically, and in computing machine, carries out frequency response function analyzing and processing in real time.
Refer to Fig. 2 and Fig. 3, in order to obtain the vibration parameters of the weak part of travelling-wave tube vibration sparking, aperture plate sample is controlled to grid-control TWT and has carried out modal test, modal parameter is obtained through parameter identification by the constrained input signal of the structure gathered test, obtain Modal frequency, damping ratio and mode are shaken shape, make the characteristic of structure each rank primary modal in a certain interested frequency range clear, the distortion of aperture plate can be observed out clearly by the shape animation that shakes, correct amendment can be made accurately like this to structural design, reduce the irrationality of structure, improve the rigidity of aperture plate.
Test result:
1, aperture plate vibration natural frequency.Refer to Fig. 6, be fixed on fixture by aperture plate, and firmly hammer knocks aperture plate, measure the vibration of aperture plate simultaneously with laser vibration measurer, do spectrum analysis by measuring the aperture plate oscillating curve obtained, obtain the natural frequency of aperture plate, its spectrum peak data are in table 1.
Table 1 spectrum peak list (engineering unit: mm/s)
| Sequence number | Frequency | Amplitude spectrum Peak | Damping ratio |
| 01 | 14235.9 | 11.4748 | 0.063％ |
| 02 | 18331.1 | 5.71416 | 0.142％ |
| 03 | 22538.6 | 1.61977 | 0.120％ |
2, the vibration shape obtains.Refer to Fig. 7 and Fig. 8, with single-frequency sound wave excitation aperture plate, the vibration information of each point is measured with laser vibration measurer, and the treated vibration shape obtaining first three rank of aperture plate.The model frequency of wire-grid structure self is very high as can be seen from Figure 8, cloudy grid spacing will be caused too small because large deformation occurs in aperture plate resonance in travelling-wave tube vibration environment certification test.Aperture plate in homogeneous tube with other structure generation translations of travelling-wave tube.
Refer to Fig. 9, the analog result of aperture plate and test findings are closely.Do that the modal test of the such engraved structure model of aperture plate is more difficult to be done, the metal spokes shape aperture plate modal test verification method of this patent introduction solves this difficult problem, actual modal test obtains desirable data result, and analog computation result can be made to be verified preferably.
Claims (2)
1. a grid-control TWT metal grid mesh Modal Experimental Method, is characterized in that, it comprises the steps:
(1) adopt the method for pointwise excitation, single-point pick-up, measuring point arranged by aperture plate test specimen; Aperture plate is fixed on the fixture of boring, consistent with physical constraint, described fixture adopt good rigidly, weight low, there is higher rigid mass ratio and the aluminum alloy materials of high damping characteristic, fixture whole block material processes, the center of gravity of fixture and test product with test table top center superposition;
(2) with hammering method to wire-grid structure with exciting, measure simultaneously its response;
(3) signal obtained is inputted computing machine after A/D converter is sampled, calculate the transport function of point of excitation and response point, obtain the frequency of aperture plate;
(4) by the method for acoustic wave excitation, entirety excitation is carried out to wire-grid structure, measure the response of each point with laser vibration measurer, and the matching carrying out transfer curve in real time in computing machine obtains the Mode Shape of aperture plate.
2. grid-control TWT metal grid mesh Modal Experimental Method according to claim 1, is characterized in that, in step (1), the shell of aperture plate is arranged 68 measuring points altogether, forms the network of aperture plate.
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| CN104239645B (en) * | 2014-09-23 | 2017-05-10 | 工业和信息化部电子第五研究所 | Design method and system for anti-vibration reliability of micro assembly component |
| CN104776963A (en) * | 2015-04-14 | 2015-07-15 | 北京强度环境研究所 | Acoustic excitation non-contact modal testing system and method |
| CN108920752B (en) * | 2018-05-25 | 2022-05-03 | 电子科技大学 | Method for synchronously updating and iteratively designing size of traveling wave tube structure |
| CN111474241A (en) * | 2020-06-10 | 2020-07-31 | 国网山西省电力公司电力科学研究院 | Method for evaluating latent fault factors existing in GIS structural state |
| CN114312906B (en) * | 2021-12-29 | 2023-06-16 | 中铁第四勘察设计院集团有限公司 | Floating slab track bed, self-vibration frequency detection method thereof and health monitoring method of vibration reduction track |
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Address after: No. 78, Zhucun Avenue West, Zhucun street, Zengcheng District, Guangzhou, Guangdong 511300 Patentee after: CHINA ELECTRONIC PRODUCT RELIABILITY AND ENVIRONMENTAL TESTING Research Institute (THE FIFTH ELECTRONIC Research Institute OF MIIT)(CEPREI LABORATORY)) Address before: 510610 No. 110 Zhuang Road, Tianhe District, Guangdong, Guangzhou, Dongguan Patentee before: Fifth Electronics Research Institute of Ministry of Industry and Information Technology |
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