Orthogonal heat grid-based laser-ultrasonic residual stress detection system and method

Abstract

This application relates to a laser ultrasonic residual stress detection system and method based on orthogonal thermal gratings, belonging to the field of stress detection technology. The system includes: a laser excitation and detection module for exciting and detecting laser ultrasonic waves on the component under test; a laser modulation module for modulating laser ultrasonic waves at different incident depths and simultaneously generating laser ultrasonic waves in the X and Y directions; a mechanical processing module for controlling the receiving positions of the X and Y direction laser ultrasonic wave signals; and a signal processing module for calculating the residual stress distribution of the component under test based on the X and Y direction laser ultrasonic waves at different incident depths and acoustoelastic theoretical stress. The laser excitation and detection module, laser modulation module, and mechanical processing module are all electrically connected to the signal processing module. This application achieves rapid, effective, and accurate detection of residual stress on the inner edges of the component under test.

Description

Technical Field

[0001] This application relates to the technical field of stress detection, and in particular to a laser ultrasonic residual stress detection system and method based on orthogonal thermal gratings. Background Technology

[0002] Metal additive manufacturing is a complex process involving the coupling of multiple physical and chemical fields. Processes such as welding, casting, forging, and machining cause internal lattice deformation in metal components, inevitably generating residual stress. This significantly reduces the ultimate strength and fatigue strength of the components, and can even lead to cracks and brittle fracture. Furthermore, during processing and use, the relaxation of residual stress causes deformation of the parts, greatly affecting the dimensional and positional accuracy of the components and the overall performance of the machine. Therefore, the detection of residual stress in metals is crucial.

[0003] Currently, non-destructive testing methods for stress fields mainly include X-ray diffraction, neutron diffraction, magnetic measurement, and ultrasonic measurement. Among these, ultrasonic measurement is widely used due to its advantages such as simple equipment, easy operation, wide measurement range, and low requirements on the test surface.

[0004] Laser ultrasonic measurement, as an emerging ultrasonic testing technology, has advantages such as non-contact, high resolution, and easy realization of rapid and automated testing of complex components.

[0005] However, current laser ultrasonic testing methods can only detect residual stress in one direction at a time. If it is necessary to detect residual stress in two directions, it is necessary to scan again in the other direction. Changing the direction of residual stress in the component under test is usually achieved by controlling the robotic arm to rotate the XY two-dimensional scanning platform to scan the component under test in the other direction. During the rotation of the component under test, the component under test may move, which causes the position of the component under test after rotation to be offset from the original position of the component under test. This results in a mismatch in the measurement position, which makes the measurement of residual stress of the component under test inaccurate. Moreover, multiple scans of the component under test are required, which takes a long time. Summary of the Invention

[0006] To achieve rapid, effective, and accurate detection of residual stress on the inner edge of the component to be tested, this application provides a laser ultrasonic residual stress detection system and method based on orthogonal thermal grids.

[0007] In a first aspect, this application provides a laser ultrasonic residual stress detection system based on orthogonal thermal gratings, employing the following technical solution:

[0008] A laser ultrasonic residual stress detection system based on orthogonal thermal gratings includes:

[0009] Laser excitation detection module;

[0010] The laser modulation module is used to modulate laser ultrasound at different incident depths and simultaneously generate laser ultrasound in the X and Y directions.

[0011] The mechanical processing module is used to control the receiving positions of the laser and ultrasonic signals in the X and Y directions.

[0012] The signal processing module is used to calculate the residual stress distribution of the component under test based on the laser-ultrasound in the X direction, the laser-ultrasound in the Y direction, and the acoustoelastic theoretical stress at different incident depths.

[0013] The laser excitation detection module, the laser modulation module, and the mechanical processing module are all electrically connected to the signal processing module;

[0014] The laser excitation and detection module includes a laser, a beam combiner, a galvanometer, and a laser ultrasonic detection device, wherein the laser ultrasonic detection device includes two interferometers, and the two interferometers are symmetrically arranged.

[0015] The output ends of the laser and the interferometer are both connected to the incident end of the beam combiner, and the output end of the beam combiner is connected to the incident end of the galvanometer.

[0016] The laser is used to output a laser beam to excite the component to be tested.

[0017] The interferometer is used to detect the ultrasonic surface wave signal of the component under test;

[0018] The beam combiner is used to combine the laser-ultrasound rays in the X direction and the laser-ultrasound rays in the Y direction into a single optical path.

[0019] The galvanometer is used to adjust the position of the laser irradiation scanning of the component to be inspected;

[0020] The laser modulation module includes a laser modulator, which is an orthogonal grating modulator or an orthogonal optical mask modulator.

[0021] By employing the above technical solution, the wavelength of the laser-excited ultrasonic wave is modulated using a laser modulation module, resulting in a laser-ultrasound with adjustable incident depth. Simultaneously, laser-ultrasounds at the same depth but in different directions can be excited. A mechanical processing module precisely controls the scanning position of the laser-ultrasound, and laser-ultrasounds at different incident depths and directions are used to detect residual stress at different depths and in different directions on the component under test. Because laser-ultrasounds in different directions are excited simultaneously, the need for a component under test to change the residual stress detection direction, and the possibility of relative movement of the detection position of the component under test, are reduced in existing technologies. This enables rapid, effective, and accurate detection of residual stress on the inner edge of the component under test. By using an orthogonal grating modulator; or an orthogonal optical mask modulator, the laser emitted by the laser can be modulated into orthogonal X-direction and Y-direction laser-ultrasounds. By acquiring the laser-ultrasound signal corresponding to the orthogonal fringe image, the residual stress distribution of the component under test can be quickly measured. This not only reduces measurement errors caused by inconsistencies in the positions of the two ultrasonic surface wave scans, improving the accuracy of residual stress measurement on the component under test, but also reduces the number of scans and increases the speed of residual stress measurement.

[0022] Optionally, the laser ultrasound is a narrowband laser ultrasound.

[0023] By adopting the above technical solution, the original laser is converted into a narrow bandwidth laser, which results in higher sensitivity and stronger penetration.

[0024] Optionally, it also includes a component processing module for acquiring material information, structural feature information and test requirement information of the component to be tested, and determining the stress detection location and at least one stress test depth based on the material information, structural feature information and test requirement information of the component to be tested.

[0025] By adopting the above technical solution, the stress detection location and stress testing depth of the component to be tested can be determined by the material information, structural feature information and testing requirements of the component to be tested. This makes the measurement of the residual stress distribution of the component to be tested more in line with the stress testing requirements of the component to be tested, and improves the applicability of residual stress detection.

[0026] Optionally, the component to be detected processing module includes a binocular camera; the binocular camera is used to acquire binocular images of the component to be detected; and structural feature information of the component to be detected is generated based on the binocular images, the structural feature information including the three-dimensional shape of the component to be detected.

[0027] By adopting the above technical solution, a binocular image of the component to be tested is obtained by scanning the component with a binocular camera. Based on the three-dimensional shape of the component to be tested from the binocular image, the three-dimensional shape can be provided to the user interface for display, so that the user can determine the testing requirements for residual stress based on the three-dimensional shape.

[0028] Secondly, this application provides a laser ultrasonic residual stress detection method based on orthogonal gratings, applied to the laser ultrasonic residual stress detection system based on orthogonal thermal gratings as described in any one of the first aspects, and adopts the following technical solution:

[0029] A laser ultrasonic residual stress detection method based on orthogonal gratings includes:

[0030] At least one laser ultrasonic length is selected based on at least one stress test depth, and the laser excitation detection module generates laser light.

[0031] The relevant parameters of the modulated laser modulation module enable the laser excitation detection module to simultaneously output narrowband laser ultrasound in the X direction and narrowband laser ultrasound in the Y direction, which have the same length as the laser ultrasound, thereby obtaining narrowband laser ultrasound in the X direction and narrowband laser ultrasound in the Y direction at different incident depths.

[0032] The mechanical processing module is used to control the narrowband laser ultrasound in the X direction and the narrowband laser ultrasound in the Y direction to scan at the stress detection position.

[0033] The signal processing module calculates the residual stress distribution of the component under test based on the narrowband laser-ultrasound in the X direction, the narrowband laser-ultrasound in the Y direction, and the acoustoelastic theoretical stress.

[0034] By adopting the above technical solution, the wavelength of the laser-excited ultrasonic wave is modulated using a laser modulation module, thereby obtaining a laser ultrasonic wave with adjustable incident depth. At the same time, laser ultrasonic waves at the same depth but in different directions can be excited simultaneously. The scanning position of the laser ultrasonic wave is precisely controlled by a mechanical processing module, and the residual stress at different depths and in different directions of the component under test is detected using laser ultrasonic waves with different incident depths and in different directions. Since laser ultrasonic waves in different directions are excited simultaneously, the possibility that the component under test needs to be changed to change the detection direction of residual stress in the prior art, and the detection position of the component under test may be relatively moved, is reduced. This enables rapid, effective, and accurate detection of residual stress on the inner edge of the component under test.

[0035] Optionally, the relevant parameters of the modulated laser modulator that enable the laser module to simultaneously output narrowband laser-ultrasound in the X direction and narrowband laser-ultrasound in the Y direction, which have the same length as the laser-ultrasound, include:

[0036] By projecting a pulsed laser through an orthogonal grating modulator, and using the lens of a galvanometer to project it onto the stress detection position on the surface of the component to be tested, an image of the orthogonal grating is formed. Under the excitation of the pulsed laser, narrowband laser ultrasound in the X direction and narrowband laser ultrasound in the Y direction with the same length as the laser ultrasound are formed.

[0037] Alternatively, a pulsed laser can be projected through an orthogonal optical mask modulator onto the stress detection position on the surface of the component to be tested, outputting narrowband laser ultrasound in the X direction and narrowband laser ultrasound in the Y direction with the same length as the laser ultrasound.

[0038] By adopting the above technical solution, the laser emitted by the laser can be modulated into orthogonal X-direction laser-ultrasound and Y-direction laser-ultrasound by an orthogonal grating modulator or an orthogonal optical mask modulator. By acquiring the laser-ultrasound signal corresponding to the orthogonal fringe image, the residual stress distribution of the component under test can be measured quickly. This not only reduces the measurement error caused by the possible inconsistency in the positions of the ultrasonic surface wave scans in two directions, thus improving the accuracy of residual stress measurement of the component under test, but also reduces the number of scans and increases the speed of measuring residual stress of the component under test.

[0039] Optionally, the calculation of the residual stress distribution of the component under test based on the narrowband laser-ultrasound in the X direction, the narrowband laser-ultrasound in the Y direction, and the acoustoelastic theoretical stress includes:

[0040] The narrowband laser ultrasonic signal detected by the laser ultrasonic detection device on the component to be tested is acquired; the narrowband laser ultrasonic signal includes narrowband laser ultrasonic signal in the X direction and narrowband laser ultrasonic signal in the Y direction.

[0041] The propagation speed of the narrowband laser-ultrasound in the X direction is calculated based on the narrowband laser-ultrasound signal in the X direction; the propagation speed of the narrowband laser-ultrasound in the Y direction is calculated based on the narrowband laser-ultrasound signal in the Y direction.

[0042] Based on the propagation speed of the narrowband laser ultrasound, the stress test depth, and the distribution of residual stress in the X and Y directions of the acoustoelastic theoretical stress test component with respect to depth.

[0043] Optionally, the propagation velocity of the narrowband laser ultrasound, the stress testing depth, and the distribution of residual stress in the X and Y directions of the acoustoelastic theoretical stress testing component with respect to depth include:

[0044] Calculate the propagation speed of the narrowband laser-ultrasound in the X direction and the propagation speed of the narrowband laser-ultrasound in the Y direction; the relationship between the speed, wavelength, and frequency of the laser-ultrasound is as follows:

[0045] c = λf

[0046] Where c is the laser-ultrasound velocity in m / s, λ is the laser-ultrasound wavelength in nm, and f is the laser-ultrasound frequency in MHz;

[0047] The formula for the stress test depth is h = 2αλ

[0048] Where h is the incident depth of the ultrasonic surface wave in mm, and α is the correction factor;

[0049] The residual stress of the component is calculated based on the propagation speed of narrowband laser-ultrasound in the X direction, the propagation speed of narrowband laser-ultrasound in the Y direction, the stress testing depth, and the acoustoelastic theoretical stress. The formula for calculating the residual stress is as follows:

[0050] σ-σ0=K(t-t0) or Δσ=KΔt, where:

[0051] Δσ is the change in residual stress (stress difference), Δσ = σ - σ0.

[0052] Δt is the change in propagation time (sound time difference), Δt = t - t0

[0053] K is the stress coefficient, which is related to the material of the component to be tested and the laser detection distance, and can be obtained through tensile testing.

[0054] In summary, this application includes at least one of the following beneficial technical effects:

[0055] 1. By using a laser modulation module to modulate the wavelength of laser-excited ultrasonic waves, laser ultrasonic waves with adjustable incident depth can be obtained. At the same time, laser ultrasonic waves at the same depth but in different directions can be excited simultaneously. The scanning position of the laser ultrasonic waves is precisely controlled by a mechanical processing module, and residual stress at different depths and in different directions of the component under test can be detected using laser ultrasonic waves with different incident depths and in different directions. Since laser ultrasonic waves in different directions are excited simultaneously, the possibility of the component under test needing to change the detection direction of residual stress in the existing technology, and the possibility of relative movement of the detection position of the component under test, is reduced. This enables rapid, effective, and accurate detection of residual stress on the inner edge of the component under test.

[0056] 2. By using an orthogonal grating modulator or an orthogonal optical mask modulator, the laser emitted by the laser can be modulated into orthogonal X-direction laser-ultrasound and Y-direction laser-ultrasound. By acquiring the laser-ultrasound signal corresponding to the orthogonal fringe image, the residual stress distribution of the component under test can be measured quickly. This not only reduces the measurement error caused by the possible inconsistency in the positions of the ultrasonic surface wave scans in two directions, thus improving the accuracy of residual stress measurement of the component under test, but also reduces the number of scans and increases the speed of measuring residual stress of the component under test. Attached Figure Description

[0057] Figure 1 This is a structural block diagram of the laser ultrasonic residual stress detection system based on orthogonal thermal gratings according to an embodiment of this application.

[0058] Figure 2 This is a connection block diagram of the device in the laser ultrasonic residual stress detection system based on orthogonal thermal grids according to an embodiment of this application.

[0059] Figure 3 This is a schematic diagram of the laser orthogonal optical path in an embodiment of this application.

[0060] Figure 4 This is a schematic diagram of the signal receiving position of the interferometer in an embodiment of this application.

[0061] Figure 5 This is a schematic diagram of the structure of the laser modulator in an embodiment of this application.

[0062] Figure 6 This is a schematic flowchart of the laser ultrasonic residual stress detection method based on orthogonal thermal grids according to an embodiment of this application.

[0063] Figure descriptions: 10, Laser excitation detection module; 101, Laser; 102, Interferometer; 103, Galvanometer; 105, Beam combiner; 20, Laser modulation module; 201, Laser modulator; 30, Mechanical processing module; 40, Signal processing module; 50, Component to be detected processing module; 501, XY 2D scanning platform; 502, Binocular camera. Detailed Implementation

[0064] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, 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, 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.

[0065] Furthermore, the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article, unless otherwise specified, generally indicates that the preceding and following related objects have an "or" relationship.

[0066] This application provides a laser ultrasonic residual stress detection system based on orthogonal thermal grids. The embodiments of this application will be further described in detail below with reference to the accompanying drawings.

[0067] Figure 1 A structural block diagram of a laser ultrasonic residual stress detection system based on an orthogonal thermal grating according to an embodiment of the present disclosure is shown.

[0068] A laser ultrasonic residual stress detection system based on orthogonal thermal grids includes a laser excitation and detection module 10, a laser modulation module 20, a mechanical processing module 30, and a signal processing module 40. The laser excitation and detection module 10, the laser modulation module 20, and the mechanical processing module 30 are all electrically connected to the signal processing module 40.

[0069] The laser excitation and detection module 10 is used to excite and detect laser-ultrasound waves for the component under test. In one embodiment, the excited laser-ultrasound waves are narrowband laser-ultrasound waves, which convert the original laser into narrowband laser-ultrasound waves, resulting in higher sensitivity and stronger penetration. The laser excitation and detection module 10 includes a laser 101, a beam combiner 105, a galvanometer 103, and a laser-ultrasound detection device. The laser-ultrasound detection device includes two interferometers 102, which are symmetrically arranged. The output ends of the laser 101 and the interferometers 102 are both connected to the incident end of the beam combiner 105. The output end of the beam combiner 105 is connected to the incident end of the galvanometer 103. The laser 101 is connected to a signal processing module 40, which adjusts the relevant parameters of the laser 101 according to the testing requirements of the component under test. In one embodiment, the laser 101 can be an Nd:YAG laser, a pulsed laser, a solid-state laser, a semiconductor laser, etc.

[0070] The laser modulation module 20 is used to modulate laser ultrasound at different incident depths and simultaneously generate laser ultrasound in the X direction and laser ultrasound in the Y direction. Figure 3 This is a schematic diagram of an orthogonal optical path modulated by a laser modulation module, where the X and Y directions are orthogonal.

[0071] Specifically, in one embodiment, the laser 101 is used to excite a laser for the component to be tested; the interferometer 102 is used to detect the ultrasonic surface wave signal of the component to be tested. Figure 4 A schematic diagram of the signal receiving positions of two interferometers according to an embodiment of this application is shown, as follows: Figure 4 As shown, the orthogonal laser ultrasonic excitation point is the stress detection position of the component to be tested. The laser 101 excites the orthogonal laser optical path towards the stress detection position. The interferometer 1 receives the laser ultrasonic signal in the Y direction, and the interferometer 2 receives the laser ultrasonic signal in the X direction. The beam combiner 105 is used to combine the laser ultrasonic light in the X direction and the laser ultrasonic light in the Y direction into a single optical path. The galvanometer 103 is used to adjust the position of the laser irradiation scanning component to be tested.

[0072] Figure 5A schematic diagram of the structure of a laser modulator according to an embodiment of this application is shown.

[0073] The laser modulation module 20 includes a laser modulator 201. In one embodiment, the laser modulator 201 is an orthogonal grating modulator, which includes an orthogonal grating and a lens. The slit widths of the orthogonal gratings are the same. The output end of the laser 101 is connected to the incident end of the orthogonal grating. The output end of the orthogonal grating is connected to the incident end of the lens. The output end of the lens is connected to the incident end of the galvanometer 103. The laser is converted into orthogonal grating lines using the orthogonal grating. Using the principle of grating refraction, the light path of the grating is refracted through the lens, so that the orthogonal laser light path is projected onto the stress detection position on the surface of the component to be tested by the galvanometer 103.

[0074] In one embodiment, the laser modulator 201 is an orthogonal optical mask modulator, which includes an orthogonal mask and a lens. The output end of the laser 101 is connected to the incident end of the orthogonal optical mask, the output end of the orthogonal optical mask is connected to the incident end of the lens, and the output end of the lens is connected to the incident end of the galvanometer 103. The orthogonal optical mask is located near the upstream of the lens, or the orthogonal optical mask is incorporated into the lens. The orthogonal optical mask is provided with a pattern designed according to the testing requirements of the component to be tested. The orthogonal laser beam path output by the laser 101 is projected onto the lens using the orthogonal optical mask, so that the orthogonal laser beam path is projected onto the stress detection position on the surface of the component to be tested through the galvanometer 103.

[0075] The laser output from laser 101 is modulated by an orthogonal grating modulator or an orthogonal optical mask modulator, so that a single excitation can simultaneously output lasers such as... Figure 3 The laser light paths in the X and Y directions shown make the laser output of laser 101 adjustable. By acquiring the laser ultrasonic signal corresponding to the orthogonal fringe image, the residual stress distribution of the component under test can be measured quickly. This not only reduces the measurement error caused by the inconsistency of the positions during the ultrasonic surface wave scans in the two directions, thus improving the accuracy of residual stress measurement of the component under test, but also reduces the number of scans and increases the speed of measuring residual stress of the component under test.

[0076] The mechanical processing module 30 is used to control the receiving positions of the X-direction and Y-direction laser ultrasonic signals, so that the receiving positions of the X-direction and Y-direction laser ultrasonic signals are consistent with the stress detection position of the component to be tested. The mechanical processing module 30 includes a robotic arm (not shown in the figure), which is connected to a galvanometer 103, an interferometer 102, and a laser 101. The robotic arm controls the movement of the galvanometer 103, interferometer 102, laser 101, and beam combiner 105, so that the laser 101 simultaneously excites laser beams in the X-direction and Y-direction directions towards the stress detection position of the component to be tested. One interferometer 102 detects the X-direction laser ultrasonic signal on the surface of the component to be tested, and the other interferometer 102 detects the Y-direction laser ultrasonic signal on the surface of the component to be tested. By adjusting the angle of the beam combiner 105, the laser ultrasonic signal excited by the laser 101 is made to coincide with the laser ultrasonic signals detected by the two interferometers 102 respectively.

[0077] The signal processing module 40 is used to calculate the residual stress distribution of the component under test based on the laser-ultrasound signals in the X and Y directions at different incident depths and the acoustoelastic theoretical stress. The signal processing module 40 includes a calculation unit, which has a preset calculation formula for the residual stress distribution of the component under test calculated based on the narrowband laser-ultrasound signals in the X and Y directions and the acoustoelastic theoretical stress. The interferometer 102 sends the laser-ultrasound signals in the X and Y directions to the signal processing module 40 for signal processing. The calculation unit calculates the residual stress distribution of the component under test at the stress detection location in both the X and Y directions along the depth direction according to the preset calculation formula.

[0078] In addition, the signal processing module 40 also includes a control unit, which is used to adjust the relevant parameters of the robotic arm posture according to the stress detection position of the component to be tested, and also to adjust the relevant parameters of the laser modulator 201 and the laser 101 according to the stress test depth of the component to be tested.

[0079] Furthermore, the laser ultrasonic residual stress detection system based on orthogonal thermal grids also includes a component processing module 50, which is electrically connected to the signal processing module 40. The component processing module 50 is used to acquire the material information, structural feature information, and test requirement information of the component to be tested. Based on the material information, structural feature information, and test requirement information of the component to be tested, it determines the stress detection position and at least one stress test depth. The determined stress detection position and at least one stress test depth are sent to the control unit of the signal processing module 40. The control unit controls the laser 101 and the laser modulation module 20 to adjust the corresponding parameters.

[0080] The component processing module 50 includes a binocular camera 502 (not shown in the figure) and an XY two-dimensional scanning platform 501. The binocular camera 502 acquires binocular images of the component to be inspected; it generates structural feature information of the component based on the binocular images, the structural feature information including the three-dimensional shape of the component. The binocular camera 502 is connected to a robotic arm, and its movement can be mechanically controlled to scan the component. The XY two-dimensional scanning platform 501 is used to place the component to be inspected, enabling the binocular camera 502 to accurately scan the component on the XY two-dimensional scanning platform 501.

[0081] In addition, the system also includes a software control platform, which is used to realize a unified control interface for the above modules, realize the control and monitoring of laser 101, interferometer 102, robotic arm, binocular camera 502 and other external auxiliary equipment, and visualize the stress detection depth and location and residual stress distribution of the component to be tested.

[0082] The above is a systematic introduction to the embodiments of this application. The following method embodiments will further illustrate the solution described in this application.

[0083] Figure 6 A schematic flowchart of a laser ultrasonic residual stress detection method based on orthogonal thermal gratings according to an embodiment of the present disclosure is shown.

[0084] A laser ultrasonic residual stress detection method based on orthogonal thermal gratings, applied to the aforementioned laser ultrasonic residual stress detection system based on orthogonal thermal gratings, includes (steps S1~S5):

[0085] Step S1: Use the component processing module 50 to obtain the material information, structural feature information and test requirement information of the component to be tested, and determine the stress detection location and at least one stress test depth based on the material information, structural feature information and test requirement information of the component to be tested.

[0086] In one embodiment, the material of the component to be tested can be input by the user into the component to be tested processing module 50, or the laser absorptivity and luminescence intensity of the sample to be tested can be determined by a reflectivity measuring device for qualitative analysis, thereby determining the material of the sample to be tested; the structural feature information includes the three-dimensional morphology, size and other information of the component to be tested; the test requirements can be preset in the component to be tested processing module 50 according to the material and structural features of the component to be tested, or can be input by the user into the component to be tested processing module 50;

[0087] Step S2: Select at least one laser ultrasonic length according to at least one stress test depth, and cause the laser excitation detection module 10 to generate laser.

[0088] In one embodiment, the component processing module 50 searches for the corresponding optimal ultrasonic length from the database based on the at least one stress test depth.

[0089] Step S3: Modulate the relevant parameters of the laser modulation module 20 so that the laser 101 simultaneously outputs narrowband laser ultrasound in the X direction and narrowband laser ultrasound in the Y direction with the same length as the laser ultrasound, thereby obtaining narrowband laser ultrasound in the X direction and narrowband laser ultrasound in the Y direction with different incident depths.

[0090] Specifically, the laser is converted into orthogonal grating lines by an orthogonal grating modulator. The optical path of the grating is refracted by the orthogonal grating refraction principle, so that the orthogonal laser optical path is projected onto the stress detection position on the surface of the component to be tested by the galvanometer 103, and narrowband laser ultrasound in the X direction and the Y direction with the same length as the laser ultrasound are output.

[0091] Alternatively, the orthogonal laser beam path output by laser 101 can be projected onto the stress detection position on the surface of the component to be tested using an orthogonal optical mask modulator, and narrowband laser ultrasound in the X direction and narrowband laser ultrasound in the Y direction with the same length as the laser ultrasound can be output.

[0092] Step S4: The mechanical processing module 30 controls the narrowband laser ultrasound in the X direction and the narrowband laser ultrasound in the Y direction to scan at the stress detection position.

[0093] Step S5: The residual stress distribution of the component under test is calculated based on the narrowband laser ultrasound in the X direction and the narrowband laser ultrasound in the Y direction and the acoustoelastic theoretical stress.

[0094] Specifically, the narrowband laser ultrasonic signal detected by the laser ultrasonic detection device on the component to be tested is acquired; the narrowband laser ultrasonic signal includes narrowband laser ultrasonic signal in the X direction and narrowband laser ultrasonic signal in the Y direction.

[0095] The propagation speed of the narrowband laser-ultrasound in the X direction is calculated based on the narrowband laser-ultrasound signal in the X direction; the propagation speed of the narrowband laser-ultrasound in the Y direction is calculated based on the narrowband laser-ultrasound signal in the Y direction.

[0096] Based on the propagation speed of the narrowband laser ultrasound, the stress test depth, and the distribution of residual stress in the X and Y directions of the acoustoelastic theoretical stress test component with respect to depth.

[0097] Specifically, the propagation speeds of the narrowband laser-ultrasound in the X direction and the Y direction are calculated; the relationship between the speed, wavelength, and frequency of the laser-ultrasound is given by the following formula:

[0098] c = λf; where c is the laser-ultrasound velocity in m / s, λ is the laser-ultrasound wavelength in nm, and f is the laser-ultrasound frequency in MHz;

[0099] The formula for the stress test depth is h=2αλ; where h is the incident depth of the ultrasonic surface wave in mm, and α is a correction coefficient;

[0100] The residual stress of the component is calculated based on the propagation speed of narrowband laser-ultrasound in the X direction, the propagation speed of narrowband laser-ultrasound in the Y direction, the stress testing depth, and the acoustoelastic theoretical stress. The formula for calculating the residual stress is as follows:

[0101] σ-σ0=K(t-t0) or Δσ=KΔt, where:

[0102] Δσ is the change in residual stress (stress difference), Δσ = σ - σ0.

[0103] Δt is the change in propagation time (sound time difference), Δt = t - t0.

[0104] K is the stress coefficient, which is related to the material of the component to be tested and the laser detection distance, and can be obtained through tensile testing.

[0105] In one embodiment, for example, based on the spectral components of λ1 and λ2 laser ultrasonic waves selected according to the stress detection depth of the sample to be tested, and h1 and h2 being the incident depths of the laser ultrasonic waves, the residual stresses σ of λ1 and λ2 laser ultrasonic waves in the X direction within the workpiece to be tested can be calculated simultaneously according to the acoustoelastic theory. 11 σ 21 The residual stresses σ1 and λ2 laser-ultrasound in the Y direction within the workpiece under test are h1 and h2. 12 σ 22 By performing differential processing on the residual stresses of laser ultrasound at two frequencies h1 and h2, the residual stresses at two gradient depths h1 and h2-h1 in the X and Y directions can be obtained, respectively. The residual stress distribution in the X direction is σ. 11 σ 21 -σ 11 Residual stress distribution in the Y direction σ 12 σ 22 -σ 12 Similarly, the residual stress distribution at different penetration depths of other ultrasonic surface waves can be deduced.

[0106] This invention provides a laser ultrasonic residual stress detection system and method based on orthogonal thermal grids. The system utilizes a laser modulation module to modulate the wavelength of laser-excited ultrasonic waves, obtaining laser ultrasonic waves with adjustable incident depths. Simultaneously, it can excite laser ultrasonic waves at the same depth but in different directions. A mechanical processing module precisely controls the scanning position of the laser ultrasonic waves, and uses laser ultrasonic waves with different incident depths and directions to detect residual stress at different depths and in different directions on the component under test. Because laser ultrasonic waves in different directions are excited simultaneously, the need for a component under test to change the residual stress detection direction, and the possibility of relative movement of the detection position of the component under test, are reduced in existing technologies. This enables rapid, effective, and accurate detection of residual stress within the component under test.

[0107] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the foregoing application concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions claimed in this application.

Claims

1. A laser ultrasonic residual stress detection system based on orthogonal heat grating, characterized in that, The application relates to a laser excitation and detection module (10), a laser modulation module (20) for modulating laser ultrasonic waves of different incident depths and simultaneously generating laser ultrasonic waves in X and Y directions, a mechanical processing module (30) for controlling the receiving positions of the laser ultrasonic wave signals in X and Y directions, and a signal processing module (40) for calculating the residual stress distribution of a component to be detected according to the laser ultrasonic waves in X and Y directions of different incident depths and the acoustic elastic theory stress. The laser excitation and detection module (10), the laser modulation module (20) and the mechanical processing module (30) are electrically connected with the signal processing module (40). The laser excitation and detection module (10) comprises a laser (101), a beam combining mirror (105), a galvanometer (103) and a laser ultrasonic detection device, wherein the laser ultrasonic detection device comprises two interferometers (102), and the two interferometers (102) are symmetrically arranged. The output end of the laser (101) and the output end of the interferometer (102) are connected with the incident end of the beam combining mirror (105), and the output end of the beam combining mirror (105) is connected with the incident end of the galvanometer (103). The laser (101) is used for outputting laser for exciting the component to be detected. The interferometer (102) is used for detecting the ultrasonic surface wave signal of the component to be detected. The beam combining mirror (105) is used for combining the light rays of the laser ultrasonic waves in X and Y directions into one light path. The galvanometer (103) is used for adjusting the position of laser irradiation scanning of the component to be detected. The laser modulation module (20) comprises a laser modulator (201), which is a quadrature grating modulator or a quadrature optical mask modulator. The laser ultrasonic wave is a narrowband laser ultrasonic wave. The application further relates to a component to be detected processing module (50) for acquiring material information, structural feature information and test requirement information of the component to be detected, determining a stress detection position and at least one stress test depth according to the material information, the structural feature information and the test requirement information of the component to be detected. The component to be detected processing module (50) comprises a binocular camera (502). The binocular camera (502) is used for acquiring a binocular image of the component to be detected, and generating structural feature information of the component to be detected based on the binocular image, wherein the structural feature information comprises the three-dimensional topography of the component to be detected.

2. The system of claim 1, wherein, The application further relates to a component to be detected processing module (50) for acquiring material information, structural feature information and test requirement information of the component to be detected, determining a stress detection position and at least one stress test depth according to the material information, the structural feature information and the test requirement information of the component to be detected.

3. The system of claim 1, wherein, The laser excitation and detection module (10), the laser modulation module (20) and the mechanical processing module (30) are electrically connected with the signal processing module (40). The laser excitation and detection module (10) comprises a laser (101), a beam combining mirror (105), a galvanometer (103) and a laser ultrasonic detection device, wherein the laser ultrasonic detection device comprises two interferometers (102), and the two interferometers (102) are symmetrically arranged.

4. The system of claim 3, wherein, The output end of the laser (101) and the output end of the interferometer (102) are connected with the incident end of the beam combining mirror (105), and the output end of the beam combining mirror (105) is connected with the incident end of the galvanometer (103). The laser (101) is used for outputting laser for exciting the component to be detected.

5. A method for detecting residual stress by laser ultrasound based on orthogonal heat grating, applied to the system for detecting residual stress by laser ultrasound based on orthogonal heat grating according to any one of claims 1-4, characterized in that, The interferometer (102) is used for detecting the ultrasonic surface wave signal of the component to be detected. The beam combining mirror (105) is used for combining the light rays of the laser ultrasonic waves in X and Y directions into one light path. The galvanometer (103) is used for adjusting the position of laser irradiation scanning of the component to be detected. The laser modulation module (20) comprises a laser modulator (201), which is a quadrature grating modulator or a quadrature optical mask modulator. The laser ultrasonic wave is a narrowband laser ultrasonic wave. The application further relates to a component to be detected processing module (50) for acquiring material information, structural feature information and test requirement information of the component to be detected, determining a stress detection position and at least one stress test depth according to the material information, the structural feature information and the test requirement information of the component to be detected. The component to be detected processing module (50) comprises a binocular camera (502). The binocular camera (502) is used for acquiring a binocular image of the component to be detected, and generating structural feature information of the component to be detected based on the binocular image, wherein the structural feature information comprises the three-dimensional topography of the component to be detected. The application further relates to a component to be detected processing module (50) for acquiring material information, structural feature information and test requirement information of the component to be detected, determining a stress detection position and at least one stress test depth according to the material information, the structural feature information and the test requirement information of the component to be detected. The laser excitation and detection module (10), the laser modulation module (20) and the mechanical processing module (30) are electrically connected with the signal processing module (40). The laser excitation and detection module (10) comprises a laser (101), a beam combining mirror (105), a galvanometer (103) and a laser ultrasonic detection device, wherein the laser ultrasonic detection device comprises two interferometers (102), and the two interferometers (102) are symmetrically arranged. The output end of the laser (101) and the output end of the interferometer (102) are connected with the incident end of the beam combining mirror (105), and the output end of the beam combining mirror (105) is connected with the incident end of the galvanometer (103). The laser (101) is used for outputting laser for exciting the component to be detected. The interferometer (102) is used for detecting the ultrasonic surface wave signal of the component to be detected. The beam combining mirror (105) is used for combining the light rays of the laser ultrasonic waves in X and Y directions into one light path. The galvanometer (103) is used for adjusting the position of laser irradiation scanning of the component to be detected. The laser modulation module (20) comprises a laser modulator (201), which is a quadrature grating modulator or a quadrature optical mask modulator. The laser ultrasonic wave is a narrowband laser ultrasonic wave. The application further relates to a component to be detected processing module (50) for acquiring material information, structural feature information and test requirement information of the component to be detected, determining a stress detection position and at least one stress test depth according to the material information, the structural feature information and the test requirement information of the component to be detected. The component to be detected processing module (50) comprises a binocular camera (502). The binocular camera (502) is used for acquiring a binocular image of the component to be detected, and generating structural feature information of the component to be detected based on the binocular image, wherein the structural feature information comprises the three-dimensional topography of the component to be detected. The application further relates to a component to be detected processing module (50) for acquiring material information, structural feature information and test requirement information of the component to be detected, determining a stress detection position and at least one stress test depth according to the material information, the structural feature information and the test requirement information of the component to be detected. The laser excitation and detection module (10), the laser modulation module (20) and the mechanical processing module (30) are electrically connected with the signal processing module (40). The laser excitation and detection module (10) comprises a laser (101), a beam combining mirror (105), a galvanometer (103) and a laser ultrasonic detection device, wherein the laser ultrasonic detection device comprises two interferometers (102), and the two interferometers (102) are symmetrically arranged. The output end of the laser (101) and the output end of the interferometer (102) are connected with the incident end of the beam combining mirror (105), and the output end of the beam combining mirror (105) is connected with the incident end of the galvanometer (103). The laser (101) is used for outputting laser for exciting the component to be detected. The interferometer (102) is used for detecting the ultrasonic surface wave signal of the component to be detected. The beam combining mirror (105) is used for combining the light rays of the laser ultrasonic waves in X and Y directions into one light path. The galvanometer (103) is used for adjusting the position of laser irradiation scanning of the component to be detected. The laser modulation module (20) comprises a laser modulator (201), which is a quadrature grating modulator or a quadrature optical mask modulator. The laser ultrasonic wave is a narrowband laser ultrasonic wave. The signal processing module (40) calculates the residual stress distribution of the component to be detected according to the X-directional and Y-directional laser ultrasonic waves and the stress calculated by the acoustic-elastic theory.

6. The method of claim 5, wherein, The related parameters of the modulated laser modulation module (20) are configured to enable the laser excitation detection module (10) to simultaneously output the X-directional and Y-directional narrow-band laser ultrasonic waves with the same wavelength as the laser ultrasonic waves, including: projecting the pulsed laser through the orthogonal grating modulator, projecting the pulsed laser on the stress detection position on the surface of the component to be detected by the lens of the galvanometer (103), forming an image of the orthogonal grating, and under the excitation of the pulsed laser, forming the X-directional and Y-directional narrow-band laser ultrasonic waves with the same wavelength as the laser ultrasonic waves. Or, projecting the pulsed laser through the orthogonal optical mask modulator, projecting the pulsed laser on the stress detection position on the surface of the component to be detected, and outputting the X-directional and Y-directional narrow-band laser ultrasonic waves with the same wavelength as the laser ultrasonic waves.

7. The method of claim 6, wherein, The residual stress distribution of the component to be detected is calculated according to the X-directional and Y-directional narrow-band laser ultrasonic waves and the stress calculated by the acoustic-elastic theory, including: obtaining the narrow-band laser ultrasonic wave signals detected by the laser ultrasonic detection device on the component to be detected; The narrow-band laser ultrasonic wave signals include X-directional and Y-directional narrow-band laser ultrasonic wave signals; The propagation speed of the X-directional narrow-band laser ultrasonic wave is calculated based on the X-directional narrow-band laser ultrasonic wave signal; The propagation speed of the Y-directional narrow-band laser ultrasonic wave is calculated based on the Y-directional narrow-band laser ultrasonic wave signal; The distribution of the residual stress of the component to be detected in the X-direction and the Y-direction with the depth is calculated based on the propagation speed of the narrow-band laser ultrasonic wave, the stress test depth, and the acoustic-elastic theory.

8. The method of claim 7, wherein, The distribution of the residual stress of the component to be detected in the X-direction and the Y-direction with the depth is calculated based on the propagation speed of the narrow-band laser ultrasonic wave, the stress test depth, and the acoustic-elastic theory, including: The propagation speed of the X-directional narrow-band laser ultrasonic wave and the propagation speed of the Y-directional narrow-band laser ultrasonic wave are calculated; The relationship formula of the speed, wavelength, and frequency of the laser ultrasonic wave is: c = λf, wherein c is the speed of the laser ultrasonic wave m / s, λ is the wavelength of the laser ultrasonic wave nm, and f is the frequency of the laser ultrasonic wave MHz; The formula of the stress test depth is h = 2αλ, wherein h is the incident depth of the ultrasonic surface wave mm, and α is a correction coefficient; The residual stress of the component is calculated based on the propagation speed of the X-directional narrow-band laser ultrasonic wave, the propagation speed of the Y-directional narrow-band laser ultrasonic wave, the stress test depth, and the acoustic-elastic theory. The formula for calculating the residual stress is: σ-σ0=K(t-t0) or Δσ=KΔt, wherein: Δσ is the change of the residual stress, that is, the stress difference, and Δσ=σ-σ0, Δt is the change of the propagation time, that is, the acoustic time difference, Δt=t-t o , and K is the stress coefficient, which is related to the material of the component to be detected and the detection distance of the laser (101) and is obtained by calibration through a tensile test.

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