CN104914158A - High-frequency electromagnetic eddy current detection system used for carbon fiber composite material damage detection - Google Patents
High-frequency electromagnetic eddy current detection system used for carbon fiber composite material damage detection Download PDFInfo
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Abstract
The invention discloses a high-frequency electromagnetic eddy current detection system used for carbon fiber composite material damage detection. The high-frequency electromagnetic eddy current detection system is characterized in that the system comprises an upper computer, a displacement platform, an eddy current probe, an analog signal processing unit and a digital signal processing unit. The analog signal processing unit comprises a high-frequency sinusoidal signal generator, a power amplifier, a signal conditioning circuit, an automatic balancing circuit and an orthogonal lock-in amplifier. The digital signal processing unit comprises an ARM microcontroller, an analog-to-digital converter, an SD card storage and USB transmission interface. The system can carry out real-time detection of damage of a carbon fiber composite material. The whole detection system works in a high frequency which can be as high as 10MHz. The detection sensitivity is high, and damage positioning of minimal damage in a carbon fiber composite material can be carried out. The whole detection system has high integration degree and has a small size.
Description
Technical field
The present invention relates to a kind of detection system for detecting carbon fibre composite damage, particularly relating to and a kind ofly based on high-frequency electromagnetic eddy current, carbon fibre composite being damaged to the system detected, belonging to the field of non destructive testing of compound substance.
Background technology
Carbon fibre composite is as a kind of high-performance fiber, have that specific strength is high, specific modulus be large, resist chemical, radiation hardness, endurance, high temperature resistant, creep resistant, conduction, heat transfer and a series of excellence such as thermal expansivity is little performance, therefore the every field of military affairs and civilian industry is widely used in, especially at aerospace field.But the security in a lot of field to structure has very high requirement, especially safety of structure is required very serious in Aero-Space, therefore the damage check of carbon fibre composite is just seemed particular importance.
In the damage check field of carbon fibre composite, most widely used lossless detection method has the detection of eddy current detection, Ultrasonic Detection, scanning acoustic microscope, X ray and thermal imaging method etc.Eddy current detection is as a kind of common lossless detection method, because its detect time untouchable, any impact can not be produced on structure and be used widely, it mainly detects based on electromagnetic induction principle, the distribution of vortex field can be affected when there being damage in conductor, around this principle just can detect the damage in conductor, eddy current detection technology is fine for the detection Detection results of conductor, but eddy current detection method also can be used for detecting compound substance.Current vortex utilize eddy current detection technology can realize as fibre breakage in carbon fibre composite, the detection of machine direction etc., even if can be utilized in the machine-shaping process of carbon fibre composite equally to detect it.Utilize eddy current detection technology can also detect the structural damage that little impact energy (0.5J) is brought, and its Detection results is than effective as ultrasonic, infrared thermography etc. of other some detection methods.
Large quantifier elimination is carried out to the eddy current detection technology of carbon fibre composite abroad, and successfully utilize eddy current detection technology to detect damage such as fibre breakage, the layering etc. that carbon fibre composite is common, and research finds, when high frequency, Detection results is better, can to the inside of carbon fibre composite observe trickleer.Moreover, external relevant unit further developed high-frequency electromagnetic eddy detection system, it detects frequency can to tens MHz MHz even up to a hundred, be successfully applied in the damage check of carbon fibre composite, at home, the high-frequency electromagnetic EDDY CURRENT research for carbon fibre composite is less, and detection system frequency of operation is general all lower, therefore, the development carrying out the high-frequency electromagnetic EDDY CURRENT of carbon fibre composite is necessary.
Summary of the invention
technical matters
The technical problem to be solved in the present invention is to provide a kind of high-frequency electromagnetic eddy detection system for carbon fibre composite damage check, for detecting the damage of carbon fibre composite, it is high that it detects frequency, can detect damage small in carbon fibre composite.
technical scheme
In order to solve above-mentioned technical matters, high-frequency electromagnetic eddy detection system for carbon fibre composite damage check of the present invention comprises host computer, displacement platform, eddy current probe, analogy signal processing unit and digital signal processing unit, wherein, analogy signal processing unit comprises high frequency sinusoidal signal generator, power amplifier, signal conditioning circuit, automatic balancing circuit and orthogonal lock-in-amplifier device, digital signal processing unit comprises ARM microcontroller, analog to digital converter, the storage of SD card and USB transmission interface, wherein
Described host computer is connected by serial ports with displacement platform, and host computer sends the motion of instruction command displacement platform to displacement platform.
Described eddy current probe is made up of drive coil and receiving coil.
In described high frequency sinusoidal signal generator, ARM microcontroller controls direct digital synthesizers chip (DDS chip) writes corresponding frequency control word and phase control words generation assigned frequency and phase place sinusoidal signal to it; The highest sinusoidal signal producing 200MHz of DDS chip, the present invention utilizes DDS chip to produce two-way sinusoidal quadrature signals, one tunnel is used for providing pumping signal to drive coil after power amplification, and detecting of feeble signal is then carried out as being supplied to lock-in amplifier with reference to signal in an other road.
Described power amplifier carries out power amplification to the high frequency sinusoidal signal that high frequency sinusoidal signal generator produces, the high frequency sinusoidal signal input stimulus coil after amplification; In sample to be tested, produce current vortex under the excitation of the high frequency sinusoidal signal that drive coil produces at high frequency sinusoidal signal generator, the change of receiving coil induced voltage or impedance reflects the position damaged in tested sample; The marking current that DDS chip produces only has 10mA, drive coil cannot be driven in tested sample to produce current vortex, need to carry out power amplification through power amplifier.
Described signal conditioning circuit carries out filtering and enlarge leadingly to the output signal of receiving coil, then inputs the process of orthogonal lock-in-amplifier device; The two-way orthogonal sine signal that the signal that receiving coil exports produces with signal generating circuit after programming amplifying sends into phase-sensitive detector (PSD) jointly, then by obtaining amplitude and phase information after low-pass filter filtering high-frequency signal; The signal of receiving coil contains some low-frequency noise signal and signal amplitude is very little, need after filtration except and amplify after could to lock-in amplifier process.
Described orthogonal lock-in-amplifier device is used for carrying out phase sensitive detection to the output signal of receiving coil, from the output signal of receiving coil, extract amplitude and the phase information of faint damage signal, and the signal of extraction is inputted ARM microcontroller after AD conversion unit process.
Described automatic balancing circuit is used for carrying out automatic zero set (AZS) to system; Before system normally detects, it is not 0 that receiving coil exports, and is a fixed signal, and much larger than damage signal, if do not suppressed, can affects the judgement of damage signal; By automatic balancing circuit, detection system output is returned to zero like this, unbalanced signal can be avoided the impact of testing result, automatic balancing circuit by binary channels DA conversion chip and sinusoidal signal produce two-way orthogonal signal that circuit produces carry out being multiplied be added after synthesis amplitude equal and phase place is contrary signal offsets unbalanced signal.
Described ARM microcontroller and host computer carry out communication and data are transmitted, and controls the data storage that direct digital synthesizers chip produces high frequency sinusoidal signal, domination number mode convertion and SD card.
Described analog to digital converter carries out data acquisition to the output signal of lock-in amplifier under the effect of ARM microcontroller, and the signal collected carries out storing and transmitting by ARM microcontroller again.
Described SD card is connected with ARM microcontroller, the result data of AD conversion unit is stored, facilitate follow-up data process under the control of ARM microcontroller.
Described ARM microcontroller is by USB transmission interface and host computer, transfer instruction and the data collected.
Described displacement platform is connected by serial ports RS232 with host computer, and host computer sends the motion of instruction command displacement platform to displacement platform.
In technical scheme of the present invention, whole system is made up of host computer and slave computer, host computer adopts graphical programming language LabVIEW to carry out writing of program, the motion of command displacement platform on the one hand, on the other hand and slave computer carries out communicating and the transmission of data, the result of detection is carried out real-time display simultaneously; Slave computer uses ARM microcontroller as key control unit, carries out detecting the adjustment of frequency and the collection of data and storage and transmission after the instruction receiving host computer.
beneficial effect
High-frequency electromagnetic eddy detection system of the present invention can detect in real time to the damage of carbon fibre composite, whole detection system is operated in high frequency, can up to 10MHz, its detection sensitivity is high, damage reason location can be carried out to the microlesion in carbon fibre composite, whole detection system degree of integration is high, and volume is little.
Accompanying drawing explanation
Fig. 1 is the high-frequency electromagnetic eddy detection system schematic diagram of one embodiment of the invention;
Fig. 2 is the high frequency sinusoidal signal generator electrical connection diagram of one embodiment of the invention;
Fig. 3 is the electrical connection diagram of the automatic balancing circuit of one embodiment of the invention;
Fig. 4 is the electrical connection diagram of the programmable amplifier of one embodiment of the invention;
Fig. 5 is the electrical connection diagram of the lock-in amplifier of one embodiment of the invention.
Embodiment
Below in conjunction with accompanying drawing, technical scheme of the present invention is further described.
As shown in Figure 1, the high-frequency electromagnetic eddy detection system for carbon fibre composite damage check of this example comprises host computer 101, ARM microcontroller 102, high frequency sinusoidal signal generator 103, signal amplification circuit 104, power amplifier 105, displacement platform 106, sample to be tested 107, automatic balancing circuit 108, drive coil and receiving coil 109, filtering and programmable amplifier 110, binary channels DAC module 111, lock-in amplifier 112 and analog to digital conversion ADC module 113.
Described host computer 101 adopts graphical programming language LabVIEW to write, one side and displacement platform 106 pass through serial communication, thus command displacement Platform movement, on the other hand to ARM microcontroller 102 send instruction control to detect before system self-poise, gather start and terminate, excitation frequency arranges and the isoparametric setting of programming amplifying multiple, also the graphical data of collection to be shown in real time simultaneously; Described ARM microcontroller 102 1 aspect and host computer are undertaken communicating by USB port and the transmission of data, by data stored in SD card, beginning and the end of analog to digital conversion ADC module 113 is controlled on the other hand by GPIO general serial mouth, produce high frequency sinusoidal pumping signal by SPI1 Interface Controller high frequency sinusoidal signal generator simultaneously, driving source is provided to drive coil, controlled the work of automatic balancing circuit 108 by SPI2 Interface Controller binary channels DAC module 111 simultaneously, before detection system work, allow system reach equilibrium state, output is 0; Signal amplification circuit 104 couples of DDS export the amplitude that sinusoidal signal is amplified to 5V; Power amplifier 105 carries out power amplification to the sinusoidal signal after amplification; Some low-frequency noise signal of output signal filtering of filtering and programmable amplifying circuit 110 pairs of receiving coils, carry out programming amplifying to the faint output signal of receiving coil simultaneously and give lock-in amplifier 112, analog-to-digital conversion ADC module 113 pairs of lock-in amplifier output signals are carried out collection and are given ARM microcontroller.
Described ARM microcontroller 102 adopts STM32F407VG chip, and it has 100 pins, and frequency of operation can reach 168MHz.
Described high frequency sinusoidal signal generator 103 adopts DDS chip AD9958 to produce, and connected by serial peripheral equipment interface SPI 1 between ARM microcontroller 102, its electrical connection diagram as shown in Figure 2, AD9958 can produce two-way orthogonal sine signal, corresponding frequency control word is write and phase control words can realize by program, in 25MHz crystal oscillator source, when inner frequency multiplication 20 times, the maximum sinusoidal signal producing 200MHz exports, DDS output signal is both-end difference output, must be converted to after Single-end output through low-pass filter filter away high frequency noise through difference channel, what low-pass filter adopted is 7 rank elliptic filters.
Described signal amplification circuit 104 adopts AD8130 chip, and DDS outputs signal amplitude and only has 1V, adopts AD8130 chip that DDS is outputed signal amplitude and is amplified to 5V.
Described power amplifier 105 adopts chip LM6321 to realize, its electric current of output that high frequency sinusoidal signal generator produces is greatly about about 10mA, drive coil cannot be driven in sample to be tested to produce current vortex, have to pass through power amplification, LM6321 chip is the power amplifier chip that a bandwidth can reach 50MHz, and its peak value output circuit can reach ± 300mA.
Described automatic balancing circuit 108 as shown in Figure 3, reaches equilibrium state before being used for making systems axiol-ogy, and namely system exports is 0.DAC8563 is two-way DA conversion chip, carry out the unbalanced signal of additive operation synthesis receiving coil output again through totalizer chip AD9361 after the two-way orthogonal sine signal that two-way exports and high frequency sinusoidal signal generator produces carries out multiplying by multiplier chip AD834, lock-in amplifier is given after the unbalanced signal that adder output signal and receiving coil export is carried out calculus of differences, the conversion of ARM microcontroller control DAC is until lock-in amplifier exports close to 0, proof system balances, and balance terminates.
As shown in Figure 4, described programmable amplifier 110 adopts AD603 chip, and receiving coil output signal is very faint, must send into lock-in amplifier and carry out analog to digital conversion again after amplifying.AD603 chip is that 0-40dB Time Bandwidth can reach 30MHz in gain-adjusted scope, and the size of gain is determined by GP and GN pin level difference, and GP pin is connected, by ARM microcontroller ride gain size with the inner DAC output pin of ARM microcontroller.
Described lock-in amplifier 112 as shown in Figure 5, comprises phase-sensitive detector (PSD) 601, and third-order low-pass filter 602; Phase-sensitive detector (PSD) adopts AD834 multiplier chip, and its bandwidth range is 0-500MHz, adopts two panels AD834 chip, respectively the two-way orthogonal signal that programmable amplifier output signal and high frequency sinusoidal signal generator produce is carried out multiplying; Phase-sensitive detector (PSD) output signal is containing direct current and frequency-doubled signal, and the cutoff frequency through being made up of AD8032 chip is only be left direct current signal after the third-order low-pass filter filtering radio-frequency component of 50Hz, and two-way direct current signal contains amplitude and the phase information of damage.
Described digital-to-analog conversion ADC module 113 is realized by AD conversion chip AD7606, and AD7606 can realize the digital-to-analog conversion of 8 passages, gathers under the control of ARM microcontroller to lock-in amplifier output signal.
Before the high-frequency electromagnetic eddy detection system of the present embodiment is started working, first host computer sends regulating parameter instruction, mainly comprise the output frequency of high frequency sinusoidal signal generator and the enlargement factor of programmable amplifier, be provided with rear host computer and send balancing instructions, ARM microcontroller reads the result of digital-to-analog conversion after receiving balancing instructions, if balance, recover master system and balance, if lack of equilibrium, then control automatic balancing circuit and perform equilibrium process, until reply host computer after system balancing; After system balancing, host computer starts command displacement Platform movement, sample to be tested is placed on displacement platform, move along with the motion of displacement platform, probe placement is above sample to be tested, current vortex is produced in sample to be tested, the distribution of current vortex can be affected when there is damage in sample to be tested, being reflected on receiving coil is exactly the change of receiving coil signal amplitude and phase information, the amplitude that different size, different depth and multi-form damage reflect and phase information also different, thus the object detecting damage can be reached.Displacement platform is often transported and is moved a step to ARM microcontroller transmission acquisition instructions, ARM microcontroller controls D/A converter module and carries out data acquisition and data are transferred to host computer by USB interface processing in real time and showing after receiving acquisition instructions, and the data collected to be saved in SD card and conveniently to check in the future.After detection completes, host computer sends END instruction, and whole system quits work.
Claims (1)
1. the high-frequency electromagnetic eddy detection system for carbon fibre composite damage check, it is characterized in that, it comprises host computer, displacement platform, eddy current probe, analogy signal processing unit and digital signal processing unit, wherein, analogy signal processing unit comprises high frequency sinusoidal signal generator, power amplifier, signal conditioning circuit, automatic balancing circuit and orthogonal lock-in-amplifier device, digital signal processing unit comprises ARM microcontroller, analog to digital converter, the storage of SD card and USB transmission interface, wherein
Described host computer is connected by serial ports with displacement platform, and host computer sends the motion of instruction command displacement platform to displacement platform;
Described eddy current probe is made up of drive coil and receiving coil;
Described high frequency sinusoidal signal generator realizes based on direct digital synthesizers chip,, the ARM microcontroller in digital signal processing unit controls direct digital synthesizers chip writes corresponding frequency control word and phase control words generation assigned frequency and phase place sinusoidal signal to it;
Described power amplifier carries out power amplification to the high frequency sinusoidal signal that high frequency sinusoidal signal generator produces, the high frequency sinusoidal signal input stimulus coil after amplification; Drive coil produces current vortex under the excitation of high frequency sinusoidal signal in sample to be tested, and the change of receiving coil induced voltage or impedance reflects the position damaged in tested sample;
Described signal conditioning circuit carries out filtering and enlarge leadingly to the output signal of receiving coil, then inputs the process of orthogonal lock-in-amplifier device;
Described orthogonal lock-in-amplifier device is used for carrying out phase sensitive detection to the output signal of receiving coil, from the output signal of receiving coil, extract amplitude and the phase information of faint damage signal, and the signal of extraction is inputted ARM microcontroller after AD conversion unit process;
Described automatic balancing circuit is used for carrying out automatic zero set (AZS) to system;
Described ARM microcontroller and host computer carry out communication and data are transmitted, and controls the data storage that direct digital synthesizers chip produces high frequency sinusoidal signal, domination number mode convertion and SD card;
Described analog to digital converter carries out data acquisition to the output signal of lock-in amplify circuit under the effect of ARM microcontroller, and the signal collected carries out storing and transmitting by ARM microcontroller again;
Described SD card is connected with ARM microcontroller, the result data of AD conversion unit is stored, facilitate follow-up data process under the control of ARM microcontroller;
Described ARM microcontroller is by USB transmission interface and host computer, transfer instruction and the data collected.
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Cited By (7)
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| CN106546657A (en) * | 2016-10-11 | 2017-03-29 | 南京航空航天大学 | A kind of eddy current probe annular array method for detecting carbon fibre composite laying direction |
| CN107819481A (en) * | 2017-10-19 | 2018-03-20 | 安徽工程大学 | A kind of microwave signal R-T unit being used in microwave communication |
| CN110514735A (en) * | 2019-09-03 | 2019-11-29 | 厦门大学 | A kind of eddy detection system of carbon fibre reinforced composite wrinkle defect |
| CN111351845A (en) * | 2020-03-18 | 2020-06-30 | 南京理工大学 | Intelligent detection device based on pulse eddy current |
| CN112629728A (en) * | 2020-12-21 | 2021-04-09 | 湖南航天天麓新材料检测有限责任公司智能检测装备分公司 | Aluminum alloy residual stress testing device and method based on eddy current |
| CN113418984A (en) * | 2021-08-05 | 2021-09-21 | 重庆大学 | Become oar bearing high strength steel crack detecting system |
| CN114812915A (en) * | 2022-06-24 | 2022-07-29 | 中国空气动力研究与发展中心低速空气动力研究所 | Pressure scanning valve circuit |
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106546657A (en) * | 2016-10-11 | 2017-03-29 | 南京航空航天大学 | A kind of eddy current probe annular array method for detecting carbon fibre composite laying direction |
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| CN112629728A (en) * | 2020-12-21 | 2021-04-09 | 湖南航天天麓新材料检测有限责任公司智能检测装备分公司 | Aluminum alloy residual stress testing device and method based on eddy current |
| CN113418984A (en) * | 2021-08-05 | 2021-09-21 | 重庆大学 | Become oar bearing high strength steel crack detecting system |
| CN114812915A (en) * | 2022-06-24 | 2022-07-29 | 中国空气动力研究与发展中心低速空气动力研究所 | Pressure scanning valve circuit |
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