A laser shock strengthening monitoring system, method, and laser shock strengthening system

Abstract

This application discloses a laser shock stabilization monitoring system, method, and system, relating to the field of laser processing technology. The monitoring system includes: a filter for filtering the optical signal generated during laser shock stabilization to obtain a filtered optical signal; a photomultiplier tube for amplifying the filtered optical signal to obtain an amplified optical signal; an acoustic acquisition unit for acquiring the acoustic signal generated during laser shock stabilization; and a computer for fusing the amplified optical signal and the acoustic signal to obtain monitoring results. This application employs a multi-source fusion online monitoring method, filtering and amplifying the plasma optical signal, and achieving rapid, intelligent, digital, and industrial-scale functionality through the fusion processing of the photoacoustic information of the plasma generated by laser shock stabilization.

Description

Technical Field

[0001] This application relates to the field of laser processing technology, and in particular to a laser shock strengthening monitoring system, method, and laser shock strengthening system. Background Technology

[0002] Aero engines are a significant symbol of a nation's overall strength and a strategic high ground in international high-end manufacturing competition. In practical applications, aero engine components endure harsh working environments and complex loads, making them susceptible to high-cycle fatigue fracture, which directly restricts the safety and reliability of aircraft during operation. Of particular concern is that high-cycle fatigue fracture is the dominant failure mode in aircraft structural components. Studies show that fatigue failure accounts for more than half of all aircraft component fractures. Therefore, pursuing improved manufacturing processes to enhance the fatigue performance of components is crucial.

[0003] Laser shock peening (LSP) is an excellent solution for high-cycle fatigue fracture. This process utilizes high-intensity pulsed laser irradiation of the metal surface to achieve plastic deformation of the material. Compared to traditional strengthening methods such as shot peening, low-plasticity calendering, and rolling, LSP offers advantages such as introducing a deeper compressive stress layer, high controllability, and no heat-affected zone after processing. The application of LSP in China has already entered a large-scale stage, and one of the key technologies for future development is online monitoring technology for LSP.

[0004] Monitoring methods for laser shock peening mainly include laser-induced plasma acoustic signals, acoustic emission signals from within the material, and laser-induced plasma spectral signals. Other methods include image recognition and natural frequency detection. However, spectral monitoring suffers from a weak signal due to strong self-absorption of plasma light after passing through water. Acoustic signal monitoring requires sensors to be attached to the workpiece, which places high demands on workpiece dimensions and is unfavorable for actual processing. Image recognition suffers from large data processing requirements and difficulty in resolution. Furthermore, natural frequencies change with stress within the material, which is also unsuitable for monitoring during actual processing.

[0005] Single monitoring methods cannot reflect the complex optical, acoustic, and electrical information involved in the laser shock fusion process. Multi-source fusion for online monitoring of laser shock fusion is still in its early stages, especially the joint monitoring of laser-induced plasma spectroscopy and laser-induced acoustic signals, which has not yet been applied. Establishing a monitoring method based on dual optical and acoustic sources, and achieving parameterized control of the laser shock fusion process through an optical-acoustic signal fusion mechanism, is of great significance for online monitoring of laser shock fusion. Summary of the Invention

[0006] This application provides a laser shock enhancement monitoring system, method, and laser shock enhancement system to solve the problems of weak light signals and the inability of a single monitoring method to reflect detailed information in existing spectral monitoring methods.

[0007] On one hand, embodiments of this application provide a laser shock enhancement monitoring system, including:

[0008] A filter is used to filter the optical signal generated during laser shock peening to obtain a filtered optical signal.

[0009] A photomultiplier tube is used to amplify filtered optical signals to obtain amplified optical signals.

[0010] A sound acquisition device is used to collect the sound signals generated during laser shock peening.

[0011] Computers are used to fuse amplified optical and acoustic signals to obtain monitoring results.

[0012] On the other hand, embodiments of this application also provide a laser shock enhancement monitoring method, including:

[0013] The optical signal generated during laser shock peening is filtered to obtain a filtered optical signal;

[0014] The filtered optical signal is amplified to obtain an amplified optical signal;

[0015] Acoustic signals generated during laser shock peening were collected.

[0016] The amplified optical and acoustic signals are fused to obtain the monitoring results.

[0017] On the other hand, this application also provides a laser shock enhancement monitoring method, including a laser enhanced shock module and the system described above.

[0018] The laser shock strengthening monitoring system, method, and laser shock strengthening system disclosed in this application have the following advantages:

[0019] By adopting a multi-source fusion online monitoring method, the plasma optical signal was filtered and amplified, and the photoacoustic information of the plasma generated by laser shock enhancement was fused and processed, realizing the functions of speed, intelligence, digitalization and industrialization. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the composition of a laser shock peening system provided in an embodiment of this application;

[0022] Figure 2 This is a schematic diagram of the system composition when selecting a filter, provided as an embodiment of this application.

[0023] Explanation of the reference numerals: 1. Laser; 2. Laser lens; 3. Plasma; 4. Constraint layer; 5. Protective layer; 6. Workpiece; 7. Moving platform; 8. Plasma optical lens; 9. Filter; 10. Photomultiplier tube; 11. Data acquisition card; 12. Computer; 13. Delay generator; 14. Oscilloscope; 15. Photodiode; 16. Sound acquisition device; 17. Spectrometer. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] Figure 1 This is a schematic diagram of a laser shock strengthening system provided in an embodiment of this application. This application also provides a laser shock strengthening monitoring system, including:

[0026] Filter 9 is used to filter the optical signal generated during laser shock enhancement to obtain a filtered optical signal;

[0027] The photomultiplier tube 10 is used to amplify the filtered optical signal to obtain an amplified optical signal;

[0028] Acoustic acquisition device 16 is used to acquire acoustic signals generated during laser shock strengthening;

[0029] Computer 12 is used to fuse amplified optical and acoustic signals to obtain monitoring results.

[0030] For example, when a laser irradiates a workpiece 6, it will generate plasma 3 and release strong light. This light is captured by a filter 9 in the form of an optical signal. After filtering, light outside the allowed transmission frequency range will be absorbed, while other optical signals will pass through the filter 9 and be further amplified by a photomultiplier tube 10 to solve the problem of weak optical signals in the prior art, which cannot be effectively monitored.

[0031] While the laser irradiation generates an optical signal, it also generates a strong acoustic signal. After the acoustic signal is collected by the acoustic acquisition device 16, it will be input into the computer 12 in the form of an electrical signal. The computer 12 will fuse the amplified optical signal and the acoustic signal to obtain the monitoring result.

[0032] In embodiments of this application, the monitoring system further includes a plasma optical lens 8, a data acquisition card 11, an oscilloscope 14, a photodiode 15, and a delay generator 13. The plasma optical lens 8 is positioned upstream of the optical path of the filter 9 and is used to focus the optical signal. Specifically, the plasma optical lens 8 can be a biconvex lens, meaning both the incident and exit surfaces of the light are convex. The data acquisition card 11 is used to transmit the amplified optical signal to the computer 12, and the oscilloscope 14 is used to transmit the acoustic signal to the computer 12. Both the data acquisition card 11 and the oscilloscope 14 are connected to the computer 12 via USB (Universal Serial Bus) cables. The photodiode 15 is used to acquire the optical signal, obtain the corresponding electrical signal, and send the electrical signal to the oscilloscope 14. After receiving the electrical signal, the oscilloscope 14 controls the acoustic acquisition device 16 to acquire the acoustic signal. Specifically, the oscilloscope 14, the acoustic acquisition device 16, and the photodiode 15 are all connected via BNC (Basic Network Card) cables. The delay generator 13 is used to receive control commands from the computer and control the output state of the photomultiplier tube 10 after delaying the control commands. The delay generator 13 is connected to the computer 12 via a BNC cable. The start time and duration of acquisition of the photomultiplier tube 10 are both controlled by the delay generator 13. The delay generator 13 sends the first pulse to the laser 1 to start the laser 1, and sends the second pulse to the photomultiplier tube 10. The interval between the two pulses is the start time of acquisition of the photomultiplier tube 10, and the duration of the second pulse is the duration of acquisition of the photomultiplier tube 10.

[0033] Furthermore, filter 9 is an ultra-narrowband filter, meaning it allows only a very narrow frequency band of light to pass through; most of the light will be absorbed, with only a small portion allowed to pass. When selecting filter 9, one can use methods such as... Figure 2 The system shown directly irradiates the workpiece 6 with a laser. The resulting light signal is focused by a plasma optical lens 8 and received by a spectrometer 17. The spectrometer 17 analyzes the light signal to obtain the corresponding spectrum. Simultaneously, the selection of the filter 9 can also utilize... Figure 1 In the system, the workpiece 6 has a protective layer 5, which can be made of aluminum foil or black tape, etc. Laser irradiation on the protective layer 5 will generate a light signal, which, after being focused, will be received by the spectrometer 17 to generate a corresponding spectrum. Specifically, the method for selecting the filter 9 includes the following steps:

[0034] The first spectrum generated when the laser irradiates the workpiece 6 is collected;

[0035] The second spectrum generated when laser light irradiates the protective layer 5 is collected;

[0036] Select the target spectral line in the second spectrum. The target spectral line also exists in the first spectrum. The amplitude of the light of the target spectral line in the first spectrum is lower than the amplitude of the light of the target spectral line in the second spectrum. At the same time, the target spectral line is also within the multiplication range of the photomultiplier tube 10.

[0037] Select a filter 9 that allows light to pass through the target spectral lines.

[0038] When selecting target spectral lines, the second spectrum can be compared with the NIST (National Institute of Standards and Technology) atomic spectral database line list. Spectral lines with larger amplitudes compared to the NIST atomic spectral database line list are selected from the second spectrum. Multiple spectral lines may be selected. These multiple spectral lines are further screened according to the following three requirements: 1. They exist in the first spectrum; 2. Their amplitude in the first spectrum is significantly lower than their amplitude in the second spectrum; 3. They are within the multiplication range of the photomultiplier tube 10. Finally, spectral lines that simultaneously meet all three requirements are selected as target spectral lines. After determining the target spectral lines, an ultra-narrowband filter that allows the transmitted light to include the target spectral lines can be selected.

[0039] Furthermore, embodiments of this application also provide a laser shock enhancement monitoring method, the method comprising:

[0040] The optical signal generated during laser shock peening is filtered to obtain a filtered optical signal;

[0041] The filtered optical signal is amplified to obtain an amplified optical signal;

[0042] Acoustic signals generated during laser shock peening were collected.

[0043] The amplified optical and acoustic signals are fused to obtain the monitoring results.

[0044] For example, when fusing amplified optical signals and acoustic signals, the amplitude characteristics of the amplified optical signals, as well as the amplitude characteristics, peak count, and time-frequency information of the acoustic signals, are extracted, and the amplitude characteristics of the amplified optical signals and the amplitude characteristics, peak count, and time-frequency information of the acoustic signals are fused.

[0045] The fused monitoring results will be displayed visually on computer 12, enabling real-time online monitoring. In the embodiments of this application, the monitoring results can reflect a wealth of information, such as the damage status of the protective layer 5 and the thickness variation of the constraint layer 4. When the amplitude of the spectral line suddenly decreases, it reflects a decrease in laser energy at the processing location; when the amplitude of the spectral line decreases significantly and generates new peaks, it reflects a certain degree of damage to the protective layer 5, because the spectral lines generated by the protective layer 5 are different from those of the workpiece 6. Simultaneously, if the constraint layer 4 suddenly thickens or thins, the spectral lines will generate a strong self-absorption effect upon passing through the constraint layer 4. Therefore, based on the reflected amplitude changes, it can be determined whether there has been a significant change in the thickness of the constraint layer 4 at that location.

[0046] This application also provides a laser shock enhancement system, which includes a laser enhanced shock module and the aforementioned monitoring system.

[0047] For example, the laser-enhanced impact module includes a laser 1 and a laser lens 2. The workpiece 6 to be processed is placed on a moving platform 7. A protective layer 5 is attached to the workpiece 6, and a constraint layer 4 formed by continuously flowing water is continuously passed through the surface of the protective layer 5.

[0048] Laser 1 is connected to computer 12 via a BNC cable, and computer 12 communicates with mobile platform 7 via Ethernet. Laser lens 2 can be a plano-convex lens, that is, its incident surface and exit surface are convex and flat, respectively, to focus the laser.

[0049] The laser emitted by laser 1 is focused by laser lens 2 and then subjected to low-energy laser impact on workpiece 6. A moving platform 7 ensures that the laser irradiates workpiece 6 at the focal point of laser lens 2. The focal length of laser lens 2 should be greater than 500mm to prevent water contamination from impact-strengthened sputtering. The laser irradiating workpiece 6 or protective layer 5 excites plasma 3. Plasma optical lens 8 focuses the light from the excited plasma 3, which is then collected by spectrometer 17 or amplified by photomultiplier tube 10 and transmitted to computer 12 for storage and analysis. The acquisition delay time and start time of spectrometer 17 are controlled by delay generator 13.

[0050] The protective layer 5 absorbs the laser energy-excited plasma 3, which, under the action of the constraint layer 4, generates a shock wave in the impact direction to strengthen the workpiece 6, and emits optical and acoustic signals in the counter-impact direction. When the optical signal passes through the constraint layer 4, its intensity becomes extremely weak due to a strong self-absorption effect. At this point, the optical signal is focused by the plasma optical lens 8, and then the target spectral line is passed through the filter 9 and amplified by the photomultiplier tube 10. Simultaneously, the amplified optical signal is received by the data acquisition card 11. The plasma optical lens 8, filter 9, photomultiplier tube 10, data acquisition card 11, photodiode 15, and acoustic sensor 16 are all placed upstream of the flow direction of the constraint layer 4, approximately 30 cm away from the plasma 3. This is because the water mist generated by the laser shock strengthening will propagate along the flow direction of the constraint layer 4, thus preventing contamination of the equipment used to collect optical and acoustic signals.

[0051] By employing the aforementioned laser shock strengthening system with a monitoring mechanism, and combining the optical and acoustic signals generated during the laser shock strengthening process, the system can reflect the processing effect, changes in the protective layer 5, and changes in the constraint layer 4 in real time, thus achieving online monitoring of laser shock strengthening. Compared to single processing methods, the system of this application can more accurately reflect information changes occurring during processing and is more geared towards industrial processing, providing an intelligent online monitoring method for future laser shock strengthening processes.

[0052] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0053] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A laser shock enhancement monitoring system, characterized in that, include: The filter (9) is used to filter the optical signal generated during the laser shock strengthening process to obtain the filtered optical signal; A photomultiplier tube (10) is used to amplify the filtered light signal to obtain an amplified light signal; The acoustic acquisition unit (16) is used to acquire the acoustic signals generated during the laser shock strengthening process; Computer (12) is used to fuse the amplified optical signal and the acoustic signal to obtain monitoring results; A plasma optical lens (8) is disposed upstream of the optical path of the filter (9), and the plasma optical lens (8) is used to focus the optical signal; The method for selecting the filter (9) includes: The first spectrum generated when the laser irradiates the workpiece (6) is collected; The second spectrum generated by laser irradiation on the protective layer (5) is collected; Select a target spectral line in the second spectrum. The target spectral line also exists in the first spectrum. The amplitude of the light of the target spectral line in the first spectrum is lower than the amplitude of the light of the target spectral line in the second spectrum. At the same time, the target spectral line is also within the multiplication range of the photomultiplier tube (10). Select the filter (9) that can transmit light through the target spectral line.

2. The laser shock enhancement monitoring system according to claim 1, characterized in that, Also includes: A data acquisition card (11) is used to transmit the amplified optical signal to the computer (12).

3. The laser shock enhancement monitoring system according to claim 1, characterized in that, Also includes: An oscilloscope (14) is used to transmit the acoustic signal to the computer (12).

4. The laser shock enhancement monitoring system according to claim 3, characterized in that, Also includes: A photodiode (15) is used to collect the optical signal, obtain the corresponding electrical signal, and send the electrical signal to the oscilloscope (14). After receiving the electrical signal, the oscilloscope (14) controls the sound acquisition device (16) to collect the sound signal.

5. The laser shock enhancement monitoring system according to claim 1, characterized in that, Also includes: The delay generator (13) is used to receive the control command from the computer and control the output state of the photomultiplier tube (10) after delaying the control command.

6. A laser shock enhancement monitoring method, wherein the method is applied to the system described in claim 1, characterized in that, include: The optical signal generated during laser shock peening is filtered to obtain a filtered optical signal; The filtered optical signal is amplified to obtain an amplified optical signal; Acoustic signals generated during laser shock peening were collected. The amplified optical signal and the acoustic signal are fused to obtain the monitoring results.

7. The laser shock enhancement monitoring method according to claim 6, characterized in that, When fusing the amplified optical signal and the acoustic signal, the amplitude characteristics of the amplified optical signal, as well as the amplitude characteristics, peak count, and time-frequency information of the acoustic signal, are extracted, and then fused together.

8. A laser shock peening system, characterized in that, It includes a laser-enhanced impact module and the system described in any one of claims 1-5.

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