CN211179651U - Novel ultrasonic detection system for metal internal defects - Google Patents
Novel ultrasonic detection system for metal internal defects Download PDFInfo
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- CN211179651U CN211179651U CN201921909728.0U CN201921909728U CN211179651U CN 211179651 U CN211179651 U CN 211179651U CN 201921909728 U CN201921909728 U CN 201921909728U CN 211179651 U CN211179651 U CN 211179651U
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Abstract
The utility model discloses a novel ultrasonic testing system of metal internal defect, the system includes that the circulator passes through the optic fibre Fizeau interferometer detecting system, fiber optic regulator, electronic accurate displacement platform, convex lens, spectroscope, space pulse laser instrument, photoelectric detector, oscilloscope and the signal analysis identification module that isolator and narrow linewidth laser instrument are connected and are constituteed, arouse the supersound at the metal surface with pulse laser, carry out non-contact detection to ultrasonic signal with optic fibre Fizeau interferometer detecting system, cooperate electronic accurate displacement platform, the metal sample that drives to be measured carries out two-dimensional optical scanning and detects, acquire the ultrasonic signal of metal surface; and processing the detection time domain signal by using a signal analysis and identification module to obtain the information of the position and the size of the defect in the metal. The system is simple to build, flexible to use, high in detection precision, nondestructive and non-contact to detect, achieves ultra-high precision photoacoustic detection of metal internal defects, and has important application prospects in the field of ultrasonic precision detection.
Description
Technical Field
The utility model belongs to laser supersound nondestructive test field, concretely relates to novel ultrasonic testing system of metal internal defect.
Background
The laser ultrasonic detection technology is used as a novel ultrasonic nondestructive detection means and is mainly used for detecting the defect conditions on the surface and inside of the material. The technology realizes the excitation and detection of ultrasound by using laser. Compared with the traditional piezoelectric ultrasonic technology, the laser ultrasonic detection technology has the advantages of non-contact, wide frequency band, high spatial resolution and the like, can normally work in special environments such as high temperature, high pressure, corrosion, radiation and the like, and has extremely strong environmental adaptability. Therefore, the laser ultrasonic detection technology is widely applied to the aspects of material characterization, defect detection, machining process monitoring and the like.
In 2017, Chuangning Wang et al published in Optics & L technology of "Width measuring of Surface slit using laser-generated radial waves", and used a laser interferometer to detect ultrasonic signals, thereby realizing quantitative measurement of rectangular defect Width and position information of aluminum plate Surface, in 2017, Zhong Yunjie et al published in Journal of nonlinear Evaluation of "vibration" of "silicon of L sensor ultrasonic Detection of Surface-defect Detection of Surface-crack-Detection" of micro laser beam used for detecting Rail crack.
This application has combined the discernment and the measurement of optic fibre sensing technique in order to realize ultrasonic signal on the basis of laser supersound, and this system has effectively reduced the purchase cost of equipment on keeping high spatial and temporal resolution, high SNR's basis to use nimble, the debugging is convenient, the precision can reach 0.01mm, all can carry out effectual detection to multiple type defects such as sample surface, inside, have certain application potentiality in laser supersound nondestructive test field.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to overcome prior art's not enough, and provide a novel ultrasonic testing system of metal internal defect, this system can carry out the ultrasonic scanning to metal internal defect and detect under the prerequisite of not damaged to carry out super high accuracy to defective position, horizontal and longitudinal dimension's information and detect.
Realize the utility model discloses the technical scheme of purpose is:
a novel ultrasonic detection system for metal internal defects comprises a narrow-line-width laser, an isolator, a circulator, an optical fiber regulator, an electric precise displacement platform, a convex lens, a spectroscope, a spatial pulse laser, a photoelectric detector, an oscilloscope and a signal analysis and identification module, wherein a metal sample to be detected is fixed on the electric precise displacement platform; the device comprises an electric precise mobile platform, a circulator, a narrow-linewidth laser, a signal analysis and identification module, an optical fiber regulator, a photoelectric detector, an oscilloscope, a detector and a circulator, wherein the circulator is arranged on the other side of the electric precise mobile platform and is regulated and fixed through the optical fiber regulator to serve as a detection head, the circulator is connected with the narrow-linewidth laser through an isolator to form an optical fiber Fizeau interferometer detection system, the output end of the circulator is further connected with the input end of the photoelectric detector, the output end of the photoelectric detector is connected with the input end of the oscilloscope, the output end of the oscilloscope is connected with the input end of the signal analysis and identification module, the detection head transmits signals to the photoelectric detector.
The space pulse laser, the output laser focus point and the optical fiber probe at the tail end of the circulator are respectively positioned at two sides of the metal sample to be detected and are positioned on the same straight line.
The space pulse laser is an Nd-YAG solid laser, the laser wavelength is 1064nm, and the pulse width is 6 ns.
The optical fiber regulator can be regulated in the X-Y-Z direction, and the regulation precision is 0.01 mm.
The narrow linewidth laser, the optical isolator, the circulator and the photoelectric detector all have working wavelengths of 1550 nm.
The signal analysis and identification module adopts the prior art, processes the detection signal through computer algorithm programming to obtain a detection result, and comprises four parts of filtering processing of the detection signal, signal identification of longitudinal waves and transverse waves, ratio calculation of the amplitude of the longitudinal waves and the transverse waves, and extraction of signal receiving time variation.
The working principle of the system is as follows: the method is characterized in that pulsed laser is used for irradiating the surface of a material, and if the laser energy is controlled to be lower than a material damage threshold, a thermoelastic effect can be triggered, so that Rayleigh wave, transverse wave, longitudinal wave and other types of ultrasonic waves are generated. When the inside of the sample has defects, the ultrasonic waves are affected by the defects in the transmission process, so that the characteristics of the signal shape, the amplitude, the receiving time and the like are changed to different degrees. The utility model discloses an extract the time domain signal characteristic of different scanning positions and to the calculation of signal characteristic, come to confirm information such as position, size, shape of defect.
Has the advantages that: the utility model provides a novel ultrasonic detection system for metal internal defects, which uses a pulse laser to excite ultrasonic waves and realizes non-contact and nondestructive ultrasonic detection; the detection system of the fiber Fizeau interferometer is used for detecting the ultrasound, so that the time and space resolution is extremely high; the signal analysis and identification module is used for accurately analyzing the information of the defects; the system is simple to build and convenient to adjust, and can normally work in severe environments such as high temperature, high voltage, strong electromagnetic interference and the like; the detectable defects are various in types, and the ultrasonic detection can be carried out on the defects of surface cracks, gaps, grooves, internal air holes, cavities and the like.
Drawings
FIG. 1 is a schematic structural diagram of a novel ultrasonic detection system for metal internal defects;
FIG. 2 is an imaging diagram of internal defects obtained by scanning;
in the figure: 1. the system comprises a narrow-linewidth laser 2, an isolator 3, a circulator 4, an optical fiber regulator 5, a photoelectric detector 6, a sample to be measured 7, an electric precise displacement platform 8, a space pulse laser 9, a spectroscope 10, a convex lens 11, a space photoelectric detector 12, an oscilloscope 13 and a signal analysis and identification module.
Detailed Description
The invention will be further elucidated with reference to the drawings and examples, without however being limited thereto.
As shown in fig. 1, a novel ultrasonic detection system for metal internal defects comprises a narrow line width laser, an isolator, a circulator, an optical fiber regulator, an electric precise displacement platform, a convex lens, a spectroscope, a spatial pulse laser, a photoelectric detector, an oscilloscope and a signal analysis and identification module, wherein a metal sample to be detected is fixed on the electric precise displacement platform, one side of the electric precise displacement platform is sequentially provided with the convex lens, the spectroscope and the spatial pulse laser, laser emitted by the spatial pulse laser is divided into two parts of energy through the spectroscope, one part of the energy is received by the spatial photoelectric detector and converted into an electric signal, and then is transmitted to the oscilloscope as a trigger signal, and the other part of the laser is focused on the surface of the metal sample to be detected fixed on the electric precise displacement platform through the convex lens and is used for exciting ultrasound; the device comprises an electric precise mobile platform, a circulator, a narrow-linewidth laser, a signal analysis and identification module, an optical fiber regulator, a photoelectric detector, an oscilloscope, a detector and a circulator, wherein the circulator is arranged on the other side of the electric precise mobile platform and is regulated and fixed through the optical fiber regulator to serve as a detection head, the circulator is connected with the narrow-linewidth laser through an isolator to form an optical fiber Fizeau interferometer detection system, the output end of the circulator is further connected with the input end of the photoelectric detector, the output end of the photoelectric detector is connected with the input end of the oscilloscope, the output end of the oscilloscope is connected with the input end of the signal analysis and identification module, the detection head transmits signals to the photoelectric detector.
The oscilloscope adopts a high-resolution oscilloscope, and the highest sampling frequency of the oscilloscope is 20 GSa/s.
The space pulse laser, the output laser focus point and the optical fiber probe at the tail end of the circulator are respectively positioned at two sides of the metal sample to be detected and are positioned on the same straight line, the positions of the space pulse laser and the laser focus point are kept unchanged during scanning, and only the detection sample is moved.
The space pulse laser is an Nd-YAG solid laser, the laser wavelength is 1064nm, and the pulse width is 6 ns.
The optical fiber regulator can be regulated in the X-Y-Z direction, and the regulation precision is 0.01 mm.
The narrow linewidth laser, the optical isolator, the circulator and the photoelectric detector all have working wavelengths of 1550 nm.
The signal analysis and identification module adopts the prior art, processes the detection signal through computer algorithm programming to obtain a detection result, and comprises four parts of filtering processing of the detection signal, signal identification of longitudinal waves and transverse waves, ratio calculation of the amplitude of the longitudinal waves and the transverse waves, and extraction of signal receiving time variation.
The metal sample that awaits measuring, on being fixed in electronic accurate displacement platform, by electronic accurate displacement platform drive and realize the scanning detection in the two-dimensional region, electronic accurate displacement platform includes the control motor, the scanning stroke is 200 × 200mm, the minimum scanning step length is 0.01 mm.
Example (b):
the method comprises the steps of using an aluminum plate sample for detection, drilling a cylindrical hole with the diameter of 2mm and the depth of 10 mm on the upper side of the aluminum plate to manufacture an internal defect to be detected, fixing the sample to be detected on a precise electric displacement platform, and adjusting the position of the sample to enable the position of the defect to be in a scanning range.
The connected ultrasonic detection system is adopted for detection, before detection, the detection system of the fiber Fizeau interferometer is debugged, and the relative distance between the end face of the optical fiber and the surface of a sample is changed through the optical fiber adjuster, so that the length of an optical fiber interference cavity is changed. Observing the output signal of the photoelectric detector, and when the output light intensity reaches the preset intensity, the interferometer is in a stable working state and can detect the ultrasonic signal; and on the other side of the sample, controlling the pulse laser to emit laser, adjusting the output intensity of the pulse laser to enable the laser energy to be smaller than the damage threshold of the sample, and simultaneously selecting a single-shot emitting mode to ensure that the interferometer can stably receive ultrasonic signals.
The relative position of the end face of the optical fiber and the laser irradiation point is adjusted to enable the end face of the optical fiber and the laser irradiation point to be in the same straight line in space, during detection, a pulse laser is started to emit a single laser beam, an ultrasonic detection waveform can be obtained on an oscilloscope through a detection system, then the detection steps are repeated, a precision electric displacement platform is controlled to drive a sample to perform point-by-point scanning detection in a 5 × 5 mm area in a step length of 0.2 mm, and the position of the optical fiber probe and the laser irradiation point is kept unchanged in scanning, and only the detection sample moves.
The method comprises the steps of obtaining an internal defect imaging graph as shown in FIG. 2 after all scanning operations are finished, collecting ultrasonic waveform data of all scanning points, analyzing and processing by using a signal analysis and identification module, filtering the waveform data by using MAT L AB software to improve the signal-to-noise ratio of the waveform, facilitating analysis and processing, observing that longitudinal wave signals and transverse wave signals are detected at 1.6 mu s and 3.3 mu s respectively, wherein the amplitude intensity of the longitudinal wave is obviously stronger than that of the transverse wave in a non-defect area and is consistent with the transmission characteristics of two types of ultrasonic waves, the intensity of the longitudinal wave gradually decreases as the scanning point gradually approaches to a defect, meanwhile, the intensity of the transverse wave signals is smaller than that of the longitudinal wave, when the longitudinal wave amplitude attenuates to the edge of the defect, the intensity of the longitudinal wave gradually increases as the scanning point gradually moves out of the defect area, and the intensity of the transverse wave again exceeds that of the transverse wave in the defect edge.
The method includes the steps of obtaining a longitudinal wave amplitude value and a transverse wave amplitude value of a sample, obtaining a scanning time of the longitudinal wave amplitude value and the transverse wave amplitude value of each group of data, and obtaining a longitudinal wave intensity distribution data in a two-dimensional scanning area.
Claims (5)
1. A novel ultrasonic detection system for metal internal defects is characterized by comprising a narrow-linewidth laser, an isolator, a circulator, an optical fiber regulator, an electric precise displacement platform, a convex lens, a spectroscope, a spatial pulse laser, a photoelectric detector, an oscilloscope and a signal analysis and identification module, wherein a metal sample to be detected is fixed on the electric precise displacement platform; the device comprises an electric precise mobile platform, a circulator, a narrow-linewidth laser, a signal analysis and identification module, an optical fiber regulator, a photoelectric detector, an oscilloscope, a detector and a circulator, wherein the circulator is arranged on the other side of the electric precise mobile platform and is regulated and fixed through the optical fiber regulator to serve as a detection head, the circulator is connected with the narrow-linewidth laser through an isolator to form an optical fiber Fizeau interferometer detection system, the output end of the circulator is further connected with the input end of the photoelectric detector, the output end of the photoelectric detector is connected with the input end of the oscilloscope, the output end of the oscilloscope is connected with the input end of the signal analysis and identification module, the detection head transmits signals to the photoelectric detector.
2. The system of claim 1, wherein the spatial pulse laser, the output laser focusing point and the fiber probe at the end of the circulator are respectively located on two sides of the metal sample to be tested and located on the same straight line.
3. The system of claim 1, wherein said spatially pulsed laser is a Nd: YAG solid-state laser with a laser wavelength of 1064nm and a pulse width of 6 ns.
4. The ultrasonic inspection system of claim 1, wherein said fiber optic adjuster is adjustable in the X-Y-Z direction to a precision of 0.01 mm.
5. The system of claim 1, wherein said narrow linewidth laser, optical isolator, circulator, photodetector all operate at 1550 nm.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR102285477B1 (en) * | 2020-10-26 | 2021-08-03 | 이현철 | Apparatus and Method for Noncontact and Non Destructive Test of Defects Inside Metal using Photoacoustic Imaging for After Induction Hardening |
| CN113295776A (en) * | 2021-05-28 | 2021-08-24 | 东南大学 | Efficient detection method of Rayleigh wave signals |
| CN114486748A (en) * | 2022-01-07 | 2022-05-13 | 华中科技大学 | Photoacoustic lithium battery detection system based on optical fiber |
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2019
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR102285477B1 (en) * | 2020-10-26 | 2021-08-03 | 이현철 | Apparatus and Method for Noncontact and Non Destructive Test of Defects Inside Metal using Photoacoustic Imaging for After Induction Hardening |
| WO2022092505A1 (en) * | 2020-10-26 | 2022-05-05 | 이현철 | Apparatus and method for non-destructive inspection of defects inside high-frequency heat-treated metal using non-contact photoacoustic images |
| CN113295776A (en) * | 2021-05-28 | 2021-08-24 | 东南大学 | Efficient detection method of Rayleigh wave signals |
| CN113295776B (en) * | 2021-05-28 | 2022-04-08 | 东南大学 | Efficient detection method of Rayleigh wave signals |
| CN114486748A (en) * | 2022-01-07 | 2022-05-13 | 华中科技大学 | Photoacoustic lithium battery detection system based on optical fiber |
| CN114486748B (en) * | 2022-01-07 | 2023-12-05 | 华中科技大学 | Photoacoustic lithium battery detection system based on optical fiber |
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