Method for measuring impact relative displacement of complex thin-wall optical-mechanical structure

Abstract

The invention belongs to the technical field of structural impact displacement measurement, and particularly discloses a method for measuring impact relative displacement of a complex thin-wall optical machine structure. The method comprises the following steps: determining a to-be-tested area of the complex thin-wall optical-mechanical structure, fixing the complex thin-wall optical-mechanical structure on an impact test bench, and installing digital image equipment; speckles are drawn in the to-be-detected area, and the position and the angle of the digital image equipment are adjusted; loading an impact response spectrum on the complex thin-wall optical-mechanical structure, and synchronously acquiring speckle images by using digital image equipment; and processing the speckle image to obtain rigid displacement data, and calculating the relative displacement of each part based on the rigid displacement data. According to the scheme, the technical problem that the relative displacement of each part is difficult to measure in an impact response spectrum test of a complex thin-wall optical-mechanical structure assembly is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of structural impact displacement measurement, and in particular relates to a method for measuring the impact relative displacement of a complex thin-walled optical-mechanical structure. Background Art

[0002] In order to meet the requirements of ultra-lightweight, the design of aerospace optomechanical structures increasingly adopts complex configurations and thin-walled features, such as T-type / L-type, variable-diameter rotating bodies, multiple weight-reducing grooves, oblique ribs, etc. At the same time, the risk of insufficient stiffness of the optomechanical structure increases, which is mainly manifested in the large deformation of a part of the optomechanical structure assembly in the impact response spectrum test, resulting in a decrease in the imaging index of the system. Therefore, measuring the relative displacement of the complex thin-walled optomechanical structure assembly during impact is of great significance to the impact transmission analysis and experimental verification of the optomechanical structure.

[0003] However, it is very difficult to measure the relative displacement of complex thin-walled optomechanical structures under impact, mainly due to the following two reasons: (1) the impact acceleration reaches 10,000 g, the frequency range covers several thousand hertz, and the loading time is in the order of milliseconds, which places high demands on the dynamic characteristics and dynamic range of the test system; (2) the complex configuration and numerous thin-walled features mean that the structural surfaces are mostly curved and inclined, and the space is small, making it difficult for contact sensors to find a suitable installation position.

[0004] At present, the commonly used displacement measurement technologies are divided into contact measurement and non-contact measurement. Contact measurement technologies include sensors, extensometers, etc. When the sensors are attached to complex thin-walled structures, they will loosen and fall off due to high-level impacts, and the mass of the sensors themselves will affect the natural frequency of the parts, causing the original resonance state to change; the extensometer has a simple structure and mature technology, but the range and gauge length are poorly adjustable and difficult to adapt to complex test environments.

[0005] Non-contact measurement technologies include laser vibrometer and digital image correlation. Laser vibrometer is based on the Doppler effect. It obtains the target's velocity and then integrates it to get the displacement. This method has high requirements on the reflectivity of the surface to be measured, is prone to introduce integration errors, and can only achieve single-point measurement. Summary of the invention

[0006] The purpose of the present invention is to provide a method for measuring the relative displacement of a complex thin-walled optomechanical structure under impact, so as to solve the technical problem of difficulty in measuring the relative displacement of each part of a complex thin-walled optomechanical structure assembly in an impact response spectrum test.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for measuring the impact relative displacement of a complex thin-walled optomechanical structure comprises: determining a test area of ​​the complex thin-walled optomechanical structure, fixing the complex thin-walled optomechanical structure on an impact test bench, and installing a digital imaging device; drawing speckles in the test area, and adjusting the position and angle of the digital imaging device; loading an impact response spectrum on the complex thin-walled optomechanical structure, and synchronously collecting speckle images using the digital imaging device; processing the speckle images to obtain rigid displacement data, and calculating the relative displacement of each component based on the rigid displacement data.

[0009] A system for measuring the impact relative displacement of a complex thin-walled optomechanical structure comprises: a preparation unit, used for determining a test area of ​​the complex thin-walled optomechanical structure, fixing the complex thin-walled optomechanical structure on an impact test bench, and installing a digital imaging device; an adjustment unit, used for drawing speckles in the test area, and adjusting the position and angle of the digital imaging device; an acquisition unit, used for loading an impact response spectrum on the complex thin-walled optomechanical structure, and synchronously acquiring a speckle image using a digital imaging device; and a measurement unit, used for processing the speckle image, obtaining rigid displacement data, and calculating the relative displacement of each component based on the rigid displacement data.

[0010] A computer-readable storage medium stores a computer program, wherein the computer program is configured to execute the above-mentioned method for measuring the impact relative displacement of a complex thin-walled optomechanical structure when running.

[0011] An electronic device comprises a memory and a processor, wherein the memory stores a computer program, and the processor is configured to execute the method for measuring the impact relative displacement of the complex thin-walled optomechanical structure through the computer program.

[0012] In the present invention, by determining the area to be tested of a complex thin-walled optomechanical structure, fixing the complex thin-walled optomechanical structure on an impact test bench, and installing a digital imaging device; drawing speckles in the area to be tested, and adjusting the position and angle of the digital imaging device; loading the complex thin-walled optomechanical structure with an impact response spectrum, and synchronously collecting speckle images with the digital imaging device; processing the speckle images to obtain rigid displacement data, and calculating the relative displacement of each part based on the rigid displacement data, the digital image correlation method is used to perform non-contact impact relative displacement measurement on the complex thin-walled optomechanical structure assembly, thereby solving the technical problem that it is difficult to measure the relative displacement of each part of the complex thin-walled optomechanical structure assembly in an impact response spectrum test. The invention is simple to operate, can perform full-field measurement, and provides reliable data support for impact transmission analysis and experimental verification of complex thin-walled optomechanical structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a flow chart of a method for measuring the impact relative displacement of a complex thin-walled optomechanical structure in an embodiment of the present invention;

[0014] Figure 2 It is a schematic diagram of the implementation process of a method for measuring the impact relative displacement of a complex thin-walled optical-mechanical structure in an embodiment of the present invention;

[0015] Figure 3 It is a schematic diagram of the overall environment of a method for measuring the impact relative displacement of a complex thin-walled optomechanical structure in an embodiment of the present invention;

[0016] Figure 4 yes Figure 3 A partial enlarged schematic diagram in the middle;

[0017] Figure 5 It is a schematic structural diagram of a system for measuring the impact relative displacement of a complex thin-walled optomechanical structure according to an embodiment of the present invention;

[0018] In the attached drawings, 1. complex thin-walled optomechanical structure; 101. part A; 102. part B; 103. part C; 2. tooling; 3. impact test bench; 4. high-speed camera; 5. bracket; 6. control box; 7. computer; 8. fill light. DETAILED DESCRIPTION

[0019] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description and claims. It should be noted that the drawings are all in very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0020] It should be noted that, in order to clearly explain the content of the present invention, the present invention specifically cites multiple embodiments to further illustrate different implementations of the present invention, wherein the multiple embodiments are enumerated rather than exhaustive. In addition, for the sake of brevity of explanation, the contents mentioned in the previous embodiments are often omitted in the subsequent embodiments. Therefore, the contents not mentioned in the subsequent embodiments can refer to the previous embodiments accordingly.

[0021] Example 1

[0022] A method for measuring the relative displacement of complex thin-walled optomechanical structures under impact, such as Figure 1 As shown, the method includes:

[0023] S1, determine the area of ​​the complex thin-walled optomechanical structure to be tested, fix the complex thin-walled optomechanical structure on the impact test bench, and install digital imaging equipment;

[0024] S2, drawing speckles on the area to be measured and adjusting the position and angle of the digital imaging device;

[0025] S3, loading shock response spectrum of complex thin-walled optomechanical structure and synchronously collecting speckle images using digital imaging equipment;

[0026] S4, processing the speckle image to obtain rigid displacement data, and calculating the relative displacement of each component based on the rigid displacement data.

[0027] As an optional implementation, determining the area to be tested of the complex thin-walled optomechanical structure includes: determining the area to be tested of each part according to the characteristics of the complex thin-walled optomechanical structure.

[0028] As an optional implementation manner, determining the area to be tested of each part includes: determining the area to be tested that is not blocked by structures and has a curvature less than a preset threshold.

[0029] As an optional implementation, installing a digital imaging device includes: installing at least two high-speed cameras and adjusting them to be horizontal.

[0030] As an optional implementation manner, drawing speckles in the area to be measured includes: drawing circular or elliptical speckles with clear boundaries in the area to be measured.

[0031] As an optional implementation, adjusting the position and angle of the digital imaging device includes: adjusting the position and angle of the high-speed camera, and adjusting the position, angle and light intensity of the fill light until the speckle area is unobstructed, without shadows and strong reflections.

[0032] As an optional implementation, processing the speckle image to obtain rigid displacement data includes: determining whether the acquired speckle image can obtain rigid displacement data; and returning to speckle drawing to repeatedly acquire the speckle image if the rigid displacement data cannot be obtained.

[0033] As an optional implementation, returning to the speckle mapping to repeatedly acquire the speckle image includes: increasing the density and area of ​​the speckle distribution.

[0034] As an optional implementation, returning to the speckle drawing to repeatedly collect the speckle image includes: adjusting the fill light and the aperture to reduce the exposure of the speckle image.

[0035] Furthermore, the specific implementation process of the above-mentioned method for measuring the relative displacement of the complex thin-walled optical-mechanical structure is not limited to the following: Figure 2 As shown, the following steps are included:

[0036] Step S100: Select the area to be tested of each part.

[0037] According to the characteristics of complex thin-walled optical and mechanical structures, select the test area of ​​each part. The test area has no obvious structural obstruction, the area is as large as possible, the curvature is as small as possible, and the relative distance between the test areas is as close as possible. The specific steps include but are not limited to:

[0038] Step S101: There is no obvious structural occlusion in the area to be tested;

[0039] Step S102: The area of ​​the region to be measured is as large as possible and the curvature is as small as possible;

[0040] Step S103: The spatial relative distance between the areas to be tested is as close as possible.

[0041] Step S200: installing measuring equipment.

[0042] Fix the complex thin-walled optical-mechanical structure on the impact test bench and install digital image-related technical equipment. The high-speed camera is a camera with a frame rate of more than 4000fps, including at least two, and the high-speed camera is adjusted to a horizontal level. The specific steps include but are not limited to:

[0043] Step S201, the high-speed cameras are cameras with a frame rate of 4000fps or more, and at least two of them are included;

[0044] Step S202: The high-speed camera is adjusted to be horizontal.

[0045] Step S300: drawing / perfecting speckle.

[0046] Manually draw speckles in the area to be tested; not limited to using a marker pen to draw speckles, and using alcohol cotton to erase them, so as to avoid the introduction of redundant materials by other methods such as spraying and water transfer. The speckle features are circular or elliptical, uniform in size, randomly distributed, with clear boundaries of the speckle area and as large an area as possible. Specific steps include but are not limited to:

[0047] Step S301, using a marker pen to draw speckles;

[0048] Step S302: The speckle features are circular or elliptical, uniform in size, and randomly distributed;

[0049] Step S303: The speckle region has clear boundaries and the area is as large as possible.

[0050] Step S400: Adjust the high-speed camera and fill light. Adjust the position and angle of the high-speed camera, and adjust the position, angle and light intensity of the fill light to ensure that the speckle area has no obstruction, no shadow, and no strong reflection.

[0051] Step S500: collecting a speckle image.

[0052] The impact response spectrum of complex thin-walled optomechanical structures is loaded, and multiple high-speed cameras synchronously collect speckle images; the image acquisition frequency is not less than 4000Hz, and the image format is TIFF.

[0053] Step S600: Process the speckle image.

[0054] Use digital image analysis software to process the speckle image and obtain rigid displacement data. Determine whether the collected speckle image can obtain rigid displacement data. If not, repeat steps S300 to S500 to increase the density and area of ​​speckle distribution, adjust the fill light and aperture to reduce the exposure of the speckle image. If it is still unsuccessful after repeating N times, repeat steps S100 to S500. The specific steps include but are not limited to:

[0055] Step S601, increasing the density and area of ​​speckle distribution;

[0056] Step S602, adjusting the fill light and the aperture to reduce the exposure of the speckle image;

[0057] Step S603, N=3-5.

[0058] Step S700: Calculate relative displacement. Select a reference and calculate the relative displacement between the parts.

[0059] To further illustrate with a specific example, the overall environment of the impact relative displacement of a complex thin-walled optomechanical structure is not limited to the following: Figure 3 As shown, the complex thin-walled optical-mechanical structure 1, the tooling 2, the impact test bench 3, the high-speed camera 4, the bracket 5, the control box 6, the computer 7 and the fill light 8 are included. The parts involved in the impact relative displacement of the complex thin-walled optical-mechanical structure 1 are not limited to the following Figure 4 As shown, it includes part A 101 , part B 102 and part C 103 .

[0060] The method for measuring the impact relative displacement of the above-mentioned complex thin-walled optomechanical structure comprises the following steps:

[0061] Step S100, according to the structural characteristics of the parts A 101, B 102 and C 103 in the complex thin-walled optomechanical structure 1, considering the area without obvious structural shielding, large area and relatively flat, and the relative distance between the areas to be tested of each part is as close as possible, the area to be tested A is selected;

[0062] Step S200: Figure 3 As shown, the complex thin-walled optical-mechanical structure 1 is fixed on the impact test bench 3 through the tooling 2. Further, two high-speed cameras 4 are installed on the bracket 5. The two high-speed cameras 4 are connected to the computer 7 through the control box 6. When the resolution of the selected high-speed camera is 1280×800, the maximum shooting frame rate is 5297fps. The two high-speed cameras 4 are adjusted to be horizontal using a level ruler.

[0063] Step S300: Figure 4As shown, a marker pen is used to draw three speckles at the area A to be tested, which are used to mark part A 101, part B 102, and part C 103 respectively. The speckle features are circular and elliptical, uniform in size, randomly distributed, with clear boundaries of the speckle area and as large an area as possible;

[0064] Step S400, adjusting the position of the bracket 5, the angles of the two high-speed cameras 4, and the position, angle, and illumination intensity of the fill light 8 so that the speckle area is free of obstruction, shadow, and strong reflection, and adjusting the aperture so that the exposure of the speckle images in the two high-speed cameras 4 is consistent;

[0065] Step S500: After the positions and angles of the two high-speed cameras 4 are fixed, calibration is performed using a calibration plate, 30-40 images of the calibration plate position and angle changes are synchronously collected, the calibration plate images are analyzed using digital image analysis software to ensure that the correction result is not greater than 0.04, the calibration file is saved, and further, the shock response spectrum is loaded into the shock test bench 3. At the same time, the two high-speed cameras 4 synchronously collect speckle images, the sampling frequency is set to 5000 Hz, and the images are saved in TIFF format;

[0066] Step S600, the digital image analysis software loads the calibration file to determine whether the acquired image can obtain strain, displacement and other data. If not, repeat steps S300 to S500 to increase the density and area of ​​speckle distribution, adjust the fill light 8 and the aperture to reduce the exposure of the speckle image. If repeated attempts are unsuccessful after 3-5 times, repeat steps S100 to S500 until the rigid displacement data is obtained through analysis.

[0067] Step S700, extract the rigid displacement data of part A 101, part B 102, and part C 103 respectively, and take part A 101 as a reference, then the impact relative displacement of part B 102 and part A 101 is:

[0068] Δs AB =s B -s A (1)

[0069] In formula (1), s A ,s B They are the rigid displacements of part A 101 and part B 102 respectively.

[0070] Taking part B 102 as a reference, the impact relative displacement of part C 103 and part B 102 is:

[0071] Δs BC =s C -s B (2)

[0072] In formula (2), sC is the rigid displacement of part C 103.

[0073] In the embodiments of the present application, a non-contact method is used to measure the relative displacement of a complex thin-walled optomechanical structure assembly without changing the quality of the structure, thereby overcoming the difficulties that cannot be measured by contact measurement methods and having the advantages of easy operation, good measurement consistency, and full-field and dynamic measurement.

[0074] Example 2

[0075] A measurement system for the impact relative displacement of complex thin-walled optomechanical structures, such as Figure 5 As shown, the system includes:

[0076] A preparation unit 502 is used to determine the area of ​​the complex thin-walled optomechanical structure to be tested, fix the complex thin-walled optomechanical structure on the impact test bench, and install a digital imaging device;

[0077] An adjustment unit 504, used to draw speckles in the area to be measured and adjust the position and angle of the digital imaging device;

[0078] The acquisition unit 506 is used to load the impact response spectrum of the complex thin-walled optomechanical structure and synchronously acquire the speckle image using a digital imaging device;

[0079] The measuring unit 508 is used to process the speckle image, obtain rigid displacement data, and calculate the relative displacement of each component based on the rigid displacement data.

[0080] Optionally, the preparation unit 502 determines the area to be tested of the complex thin-walled optomechanical structure, including: determining the area to be tested of each part according to the characteristics of the complex thin-walled optomechanical structure.

[0081] Optionally, the preparation unit 502 determines the area to be tested of each part, including: determining the area to be tested that is not blocked by structures and has a curvature less than a preset threshold.

[0082] Optionally, the preparation unit 502 installs a digital imaging device, including: installing at least two high-speed cameras and adjusting them to be horizontal.

[0083] Optionally, the adjusting unit 504 draws speckles in the area to be measured, including: drawing circular or elliptical speckles with clear boundaries in the area to be measured.

[0084] Optionally, the adjustment unit 504 adjusts the position and angle of the digital imaging device, including: adjusting the position and angle of the high-speed camera, and adjusting the position, angle and light intensity of the fill light until the speckle area is free of obstruction, shadow and strong reflection.

[0085] Optionally, the acquisition unit 508 processes the speckle image to obtain rigid displacement data, including: determining whether the acquired speckle image can obtain rigid displacement data; and returning to speckle drawing to repeatedly acquire the speckle image if the rigid displacement data cannot be obtained.

[0086] Optionally, the acquisition unit 508 returns to speckle drawing to repeatedly acquire a speckle image, including: increasing the density and area of ​​speckle distribution.

[0087] Optionally, the acquisition unit 508 returns to speckle drawing to repeatedly acquire the speckle image, including: adjusting the fill light and the aperture to reduce the exposure of the speckle image.

[0088] In an embodiment of the present application, a test area of ​​a complex thin-walled optomechanical structure is determined, the complex thin-walled optomechanical structure is fixed on an impact test bench, and a digital imaging device is installed; a speckle pattern is drawn in the test area, and the position and angle of the digital imaging device are adjusted; an impact response spectrum is applied to the complex thin-walled optomechanical structure, and a speckle image is synchronously acquired using a digital imaging device; the speckle image is processed to obtain rigid displacement data, and the relative displacement of each part is calculated based on the rigid displacement data, thereby using a digital image correlation method to perform non-contact impact relative displacement measurement of the complex thin-walled optomechanical structure assembly, thereby solving the technical problem of difficulty in measuring the relative displacement of each part of the complex thin-walled optomechanical structure assembly in an impact response spectrum test. The operation is simple, and full-field measurement can be performed, thereby providing reliable data support for impact transmission analysis and experimental verification of complex thin-walled optomechanical structures.

[0089] Example 3

[0090] Another aspect of the embodiments of the present invention further provides an electronic device for implementing the above-mentioned method for measuring the relative displacement of the complex thin-walled optomechanical structure under impact, and the electronic device is not limited to being a terminal device or a server in the system. The electronic device is not limited to including a memory and a processor, the memory stores a computer program, and the processor is configured to execute the steps in any of the above-mentioned method embodiments through the computer program.

[0091] Example 4

[0092] Another aspect of the embodiments of the present invention provides a computer program product or a computer program, which includes computer instructions stored in a computer-readable storage medium. The processor of the computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device executes the method provided in various optional embodiments of the above-mentioned method for measuring the relative displacement of the impact of the complex thin-walled optomechanical structure. The computer program is configured to execute the steps of any of the above-mentioned method embodiments when it is run.

Claims

1. A method for measuring the impact relative displacement of a complex thin-walled optomechanical structure, characterized in that: include: Determine the area of ​​the complex thin-walled optomechanical structure to be tested, fix the complex thin-walled optomechanical structure on the impact test bench, and install digital imaging equipment; Draw speckle on the area to be measured and adjust the position and angle of the digital imaging device; Load the shock response spectrum of complex thin-walled optomechanical structures and synchronously collect speckle images using digital imaging equipment; The speckle image is processed to obtain rigid displacement data, and the relative displacement of each component is calculated based on the rigid displacement data.

2. The method for measuring the impact relative displacement of a complex thin-walled optical-mechanical structure according to claim 1, characterized in that: Determine the area to be tested for complex thin-walled optomechanical structures, including: According to the characteristics of complex thin-walled optomechanical structures, the areas to be tested for each part are determined.

3. The method for measuring the impact relative displacement of a complex thin-walled optical-mechanical structure according to claim 2, characterized in that: Determine the areas to be tested for each part, including: Determine the area to be tested that has no structure occlusion and a curvature less than a preset threshold.

4. The method for measuring the impact relative displacement of a complex thin-walled optical-mechanical structure according to claim 1, characterized in that: Installation of digital imaging equipment, including: Install at least two high-speed cameras and adjust them to be level.

5. The method for measuring the impact relative displacement of a complex thin-walled optical-mechanical structure according to claim 1, characterized in that: Draw speckle on the area to be measured, including: Draw circular or elliptical speckles with clear boundaries in the area to be tested.

6. The method for measuring the impact relative displacement of a complex thin-walled optical-mechanical structure according to claim 4, characterized in that: Adjust the position and angle of digital imaging equipment, including: Adjust the position and angle of the high-speed camera, and adjust the position, angle and light intensity of the fill light until the speckle area is unobstructed, without shadows or strong reflections.

7. The method for measuring the impact relative displacement of a complex thin-walled optical-mechanical structure according to claim 1, characterized in that: Process the speckle image to obtain rigid displacement data, including: Determine whether the collected speckle image can obtain rigid displacement data; In the case where rigid displacement data cannot be obtained, the speckle mapping is returned to repeatedly acquire the speckle image.

8. The method for measuring the impact relative displacement of a complex thin-walled optical-mechanical structure according to claim 7, characterized in that: Return to Speckle Plotting to repeatedly acquire speckle images, including: Increase the density and area of ​​speckle distribution.

9. The method for measuring the impact relative displacement of a complex thin-walled optical-mechanical structure according to claim 7, characterized in that: Return to Speckle Plotting to repeatedly acquire speckle images, including: Adjust the fill light and aperture to reduce the exposure of the speckle image.

10. A system for measuring the relative displacement of complex thin-walled optomechanical structures under impact, characterized in that: include: A preparation unit is used to determine the area of ​​the complex thin-walled optomechanical structure to be tested, fix the complex thin-walled optomechanical structure on the impact test bench, and install a digital imaging device; An adjustment unit, used for drawing speckles on the area to be measured and adjusting the position and angle of the digital imaging device; An acquisition unit is used to load the impact response spectrum of the complex thin-walled optomechanical structure and synchronously acquire the speckle image using a digital imaging device; The measuring unit is used to process the speckle image, obtain rigid displacement data, and calculate the relative displacement of each part based on the rigid displacement data.

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