A method and system for thermal distortion field decoupling based on two-dimensional vision measurement

Abstract

The present application belongs to the technical field of thermal load deformation and force load deformation measurement, and relates to a thermal and force deformation field decoupling method and system based on two-dimensional visual measurement. According to the temperature field at discrete temperatures, the thermal deformation field at discrete temperatures and the corresponding temperature, and by using a binary function model, the influence coefficient of fitting temperature on thermal strain is obtained, the jumps between discrete data are eliminated, and the continuity and prediction ability of thermal strain are improved. According to the influence coefficient of fitting temperature on thermal strain and the binary function model, a fitted binary function model is obtained, which is more in line with the actual material properties. According to the temperature field under the thermal and force coupling condition, the deformation field under the thermal and force coupling condition and the fitted binary function model, an equivalent thermal deformation field is obtained, the thermal and force coupling deformation is decoupled, the dynamic correlation of thermal strain and deformation field is realized, and the decoupling precision is improved.

Description

Technical Field

[0001] This invention belongs to the field of thermal load deformation and force load deformation measurement technology, and relates to a method and system for decoupling thermal deformation fields based on two-dimensional vision measurement. Background Technology

[0002] In the aerospace field, the problem of thermo-coupling deformation measurement has always existed and has limited the development of vector nozzles for aerospace engines. This coupling effect makes it difficult to distinguish the contribution of different factors to deformation in engineering, and it is difficult to find the source of the problem when a fault occurs. Conventional contact strain gauge measurement methods have problems such as inaccurate measurement of deformation field components and temperature field information, and the measurement accuracy cannot be guaranteed. Visual measurement methods are non-contact, high-precision, and high-efficiency measurement methods that can achieve simultaneous measurement of temperature field and deformation field while ensuring measurement accuracy.

[0003] Specifically, for thermo-mechanical coupling deformation in high-temperature scenarios, the deformation mainly includes two parts: force-loaded deformation and thermal-loaded deformation. The thermal-loaded deformation of materials is mainly determined by the thermal expansion coefficient of materials in different temperature ranges. Contact methods cannot accurately map the temperature field and thermal strain field. The deformation measurement of electronic strain gauges is greatly affected by temperature and cannot accurately measure the anisotropic deformation tensor. For accurate mapping of the temperature field and deformation field in thermo-mechanical coupling deformation measurement, accurate alignment of the field of view of infrared cameras and ordinary cameras is required. Conventional camera calibration schemes cannot meet the measurement requirements. Summary of the Invention

[0004] The purpose of this invention is to provide a method and system for decoupling thermo-deformation fields based on two-dimensional vision measurement, so as to solve the technical problem that conventional camera measurement schemes cannot meet the measurement requirements of temperature field and deformation field.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] In a first aspect, the present invention provides a method for decoupling a thermo-deformation field based on two-dimensional visual measurement, comprising the following steps:

[0007] The temperature field, thermal deformation field, temperature field under thermo-mechanical coupling conditions, and deformation field under thermo-mechanical coupling conditions of the material under test are obtained at discrete temperatures.

[0008] Based on the temperature field under discrete temperature, the thermal deformation field under discrete temperature, and the corresponding temperature, the influence coefficient of the fitting temperature on thermal strain is obtained by using a bivariate function model.

[0009] The fitted bivariate function model is obtained based on the influence coefficient of the fitted temperature on thermal strain and the bivariate function model.

[0010] The equivalent thermal deformation field is obtained based on the temperature field under thermo-coupling conditions, the deformation field under thermo-coupling conditions, and the fitted bivariate function model.

[0011] Furthermore, the temperature field under discrete temperature, the thermal deformation field under discrete temperature, the temperature field under thermo-coupling conditions, and the deformation field under thermo-coupling conditions are all acquired using the same visual measurement system. The visual measurement system includes an infrared camera and a regular camera with fixed relative positions. Before the visual measurement system acquires data, the internal and external parameters of the infrared camera and the regular camera are calibrated.

[0012] Furthermore, it also includes the following steps:

[0013] Acquire ordinary camera images of the material under test under thermo-coupling conditions using an ordinary camera, and obtain the deformation field under thermo-coupling conditions based on the ordinary camera images of the material under test and the digital image correlation method.

[0014] An infrared camera image of the material under test under thermo-coupling conditions is acquired using an infrared camera. The temperature field under thermo-coupling conditions is obtained based on the infrared camera image of the material under test and a temperature conversion algorithm.

[0015] Furthermore, the calibration of the intrinsic and extrinsic parameters of the infrared camera and the ordinary camera includes:

[0016] Obtain the center coordinates of the infrared camera marker points acquired by the infrared camera;

[0017] Obtain the center coordinates of the ordinary camera marker points acquired by the ordinary camera;

[0018] The internal and external parameters of the ordinary camera and the infrared camera are calibrated using the center coordinates of the marker points of the ordinary camera and the infrared camera.

[0019] Furthermore, the influence coefficient of the fitting temperature on thermal strain is obtained by using a bivariate function model based on the temperature field and thermal deformation field at the discrete temperature, and the corresponding temperature. The formula for obtaining the influence coefficient of the fitting temperature on thermal strain is as follows:

[0020]

[0021]

[0022]

[0023]

[0024] In the formula: For thermal strain, To fit the influence coefficient of temperature on thermal strain, This represents the temperature difference between two points in time. for Strain increment in direction, for Strain increment in direction, for Strain increment in the synthesis direction For the first time right Influence coefficient, For the first time right Influence coefficient, For the first time right Influence coefficient, For the first Time 1 pair Influence coefficient, For the first time right Influence coefficient, For the first time right Influence coefficient, For the first time right Influence coefficient, For the first Time 1 pair Influence coefficient, For the first Temperature at any moment For the first Temperature at any moment For the first Time and the The average temperature at any given time.

[0025] Furthermore, obtaining the equivalent thermal deformation field based on the temperature field under thermo-coupling conditions, the deformation field under thermo-coupling conditions, and the fitted bivariate function model includes:

[0026] The equivalent thermal deformation field is obtained based on the temperature field under thermo-coupling conditions and the fitted binary function model.

[0027] The load deformation field is separated from the deformation field under thermo-mechanical coupling conditions using an equivalent thermal deformation field.

[0028] Furthermore, the load deformation field is separated from the deformation field under thermo-coupling conditions using an equivalent thermal deformation field, and the separation formula is as follows:

[0029]

[0030] In the formula: for Directional strain, for Directional strain, for Directional shear strain, For the load deformation field Directional strain, For the load deformation field Directional strain, For the load deformation field Directional shear strain, For thermal deformation field Directional strain, For thermal deformation field Directional strain, is a bivariate fitting function for thermal strain.

[0031] Secondly, the present invention provides a thermo-deformation field decoupling system based on two-dimensional visual measurement, comprising:

[0032] The data acquisition module is used to acquire the temperature field, thermal deformation field, temperature field under thermo-mechanical coupling conditions, and deformation field under thermo-mechanical coupling conditions of the material under test at discrete temperatures.

[0033] The influence coefficient fitting module is used to obtain the influence coefficient of the fitting temperature on thermal strain based on the temperature field, the thermal deformation field and the corresponding temperature at discrete temperatures, and using a bivariate function model.

[0034] The module for obtaining the fitted bivariate function model is used to obtain the fitted bivariate function model based on the influence coefficient of the fitted temperature on thermal strain and the bivariate function model.

[0035] The equivalent thermal deformation field acquisition module is used to obtain the equivalent thermal deformation field based on the temperature field under thermo-coupling conditions, the deformation field under thermo-coupling conditions, and the fitted bivariate function model.

[0036] Thirdly, the present invention provides an electronic device, comprising: a processor; a memory for storing computer program instructions; and a method for implementing a thermo-deformation field decoupling method based on two-dimensional vision measurement when executing the computer program.

[0037] Thirdly, the present invention provides a storage medium storing computer program instructions, characterized in that, when the computer program instructions are loaded and run by a processor, the processor executes a thermo-deformation field decoupling method based on two-dimensional visual measurement.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] This invention uses a bivariate function model to obtain the influence coefficient of the fitted temperature on thermal strain based on the temperature field and thermal deformation field under discrete temperatures, thereby eliminating jumps between discrete data. A fitted bivariate function model is obtained based on the influence coefficient of the fitted temperature on thermal strain and the bivariate function model, making it more closely resemble the actual material properties, reducing fitting errors, and helping to reduce the overhead of repeated fitting. An equivalent thermal deformation field is obtained based on the temperature field and deformation field under thermo-coupling conditions, and the fitted bivariate function model, realizing the dynamic correlation between thermal strain and deformation field and improving decoupling accuracy. This invention significantly improves the decoupling accuracy of the thermo-coupling deformation field by combining visual measurement with a bivariate function model, meeting the high-precision deformation measurement requirements of aerospace engine vector nozzles.

[0040] The system of this invention includes a data acquisition module, an influence coefficient fitting module, a fitted bivariate function model acquisition module, and an equivalent thermal deformation field acquisition module. The data acquisition module acquires the temperature field, thermal deformation field, and temperature and deformation fields under thermo-coupling conditions of the material under test at discrete temperatures. The influence coefficient fitting module acquires the influence coefficient of the fitted temperature on thermal strain based on the temperature field, thermal deformation field, and corresponding temperature at discrete temperatures, using a bivariate function model. The fitted bivariate function model acquisition module obtains the fitted bivariate function model based on the influence coefficient of the fitted temperature on thermal strain and the bivariate function model. The equivalent thermal deformation field acquisition module acquires the equivalent thermal deformation field based on the temperature field, deformation field, and fitted bivariate function model under thermo-coupling conditions. These modules work together to significantly improve the decoupling accuracy of the thermo-coupling deformation field, meeting the high-precision requirements for deformation measurement in aerospace engine vector nozzles.

[0041] The electronic device of this invention can also significantly improve the decoupling accuracy of the thermo-coupled deformation field, meeting the high-precision requirements of aerospace engine vector nozzles for deformation measurement. Attached Figure Description

[0042] Figure 1 This is a flowchart of a method according to an embodiment of the present invention;

[0043] Figure 2 This is a system block diagram of an embodiment of the present invention;

[0044] Figure 3 This is a flowchart of the thermo-deformation field decoupling method based on two-dimensional vision measurement according to an embodiment of the present invention;

[0045] Figure 4 This is a structural configuration diagram of a conventional camera and an infrared camera according to an embodiment of the present invention;

[0046] Figure 5 This is a schematic diagram of a specially designed calibration plate and calibration process according to an embodiment of the present invention;

[0047] Figure 6 This is a flowchart of the overall algorithm for the thermo-deformation field decoupling method of two-dimensional visual measurement according to an embodiment of the present invention.

[0048] Figure 7 This is a schematic diagram of the thermal decoupling process according to an embodiment of the present invention.

[0049] Among them: 1. Ordinary camera 1; 2. Infrared camera 2; 3. Camera connecting crossbeam; 4. Special calibration plate; 5. Speckle area; 6. Infrared light source; 7. Blue light source; 12. Hybrid binocular camera; L1. Encoded marker point; L2. Unencoded marker point; L3. Infrared high reflectivity coating; L4. Infrared blocking coating; a1. Field of view of ordinary camera; a2. Field of view of infrared camera. Detailed Implementation

[0050] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0051] It should be noted that the terms "first," "second," etc., in the specification and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0052] The present invention will now be described in further detail with reference to the accompanying drawings:

[0053] See Figure 1 This invention discloses a method for decoupling a thermo-deformation field based on two-dimensional visual measurement, comprising the following steps:

[0054] S1 acquires the temperature field, thermal deformation field, temperature field under thermo-coupling conditions, and deformation field under thermo-coupling conditions of the material under test at discrete temperatures, providing a complete dataset for subsequent decoupling, covering the deformation behavior of the material under different conditions, and avoiding decoupling errors caused by missing data.

[0055] In this embodiment of the invention, the temperature field under discrete temperature, the thermal deformation field under discrete temperature, the temperature field under thermo-coupling conditions, and the deformation field under thermo-coupling conditions are all acquired using the same visual measurement system. The visual measurement system includes an infrared camera 2 and a regular camera 1 with fixed relative positions. Before the visual measurement system acquires data, the internal and external parameters of the infrared camera 2 and the regular camera 1 are calibrated.

[0056] In this embodiment of the invention, the following steps are also included:

[0057] Acquire ordinary camera images of the material under test under thermo-coupling conditions using ordinary camera 1, and obtain the deformation field under thermo-coupling conditions based on the ordinary camera images of the material under test and the digital image correlation method.

[0058] Acquire infrared camera images of the material under test under thermo-coupling conditions using infrared camera 2, and obtain the temperature field under thermo-coupling conditions based on the infrared camera images of the material under test and a temperature conversion algorithm.

[0059] In this embodiment of the invention, the calibration of the intrinsic and extrinsic parameters of the infrared camera 2 and the ordinary camera 1 includes:

[0060] Obtain the center coordinates of the infrared camera marker points acquired by the infrared camera 2;

[0061] Obtain the center coordinates of the ordinary camera marker points acquired by the ordinary camera 1;

[0062] The internal and external parameters of the ordinary camera 1 and the infrared camera 2 are calibrated using the center coordinates of the marker points of the ordinary camera and the infrared camera.

[0063] S2, based on the temperature field and thermal deformation field under discrete temperature, and the corresponding temperature, uses a bivariate function model to obtain the influence coefficient of the fitting temperature on thermal strain, eliminating jumps between discrete data. Compared with traditional piecewise linear interpolation, the bivariate function model can more smoothly describe the change of thermal strain with temperature, reducing errors caused by data discretization.

[0064] In this embodiment of the invention, the formula for obtaining the influence coefficient of fitting temperature on thermal strain is as follows:

[0065]

[0066]

[0067]

[0068]

[0069] In the formula: For thermal strain, To fit the influence coefficient of temperature on thermal strain, This represents the temperature difference between two points in time. for Strain increment in direction, for Strain increment in direction, for Strain increment in the synthesis direction For the first time right Influence coefficient, For the first time right Influence coefficient, For the first time right Influence coefficient, For the first Time 1 pair Influence coefficient, For the first time right Influence coefficient, For the first time right Influence coefficient, For the first time right Influence coefficient, For the first Time 1 pair Influence coefficient, For the first Temperature at any moment For the first Temperature at any moment For the first Time and the The average temperature at any given time.

[0070] S3. Based on the influence coefficient of the fitting temperature on thermal strain and the bivariate function model, the fitted bivariate function model is obtained, which makes it more in line with the actual material properties, reduces fitting error, reduces the sensitivity of the optimized model to noise and outliers, improves the stability of deformation field decoupling, and helps to reduce the cost of repeated fitting.

[0071] S4 obtains the equivalent thermal deformation field based on the temperature field under thermal coupling conditions, the deformation field under thermal coupling conditions, and the fitted bivariate function model, decouples the thermal coupling deformation, realizes the dynamic correlation between thermal strain and deformation field, and improves the decoupling accuracy.

[0072] This invention significantly improves the decoupling accuracy of thermo-coupled deformation fields by combining visual measurement with a binary function model, meeting the high-precision requirements of aerospace engine vector nozzles for deformation measurement. During data acquisition, simultaneous measurement of the temperature and deformation fields is achieved, improving measurement efficiency and reducing the need for multiple measurements of the aerospace engine vector nozzle. The ability to simultaneously acquire temperature and deformation field information ensures measurement accuracy.

[0073] In this embodiment of the invention, obtaining the equivalent thermal deformation field based on the temperature field under thermo-coupling conditions, the deformation field under thermo-coupling conditions, and the fitted bivariate function model includes:

[0074] The equivalent thermal deformation field is obtained based on the temperature field under thermo-coupling conditions and the fitted binary function model.

[0075] The load deformation field is separated from the deformation field under thermo-mechanical coupling conditions using an equivalent thermal deformation field.

[0076] In this embodiment of the invention, the load deformation field is separated from the deformation field under thermo-coupling conditions using an equivalent thermal deformation field. The separation formula is as follows:

[0077]

[0078] In the formula: for Directional strain, for Directional strain, for Directional shear strain, For the load deformation field Directional strain, For the load deformation field Directional strain, For the load deformation field Directional shear strain, For thermal deformation field Directional strain, For thermal deformation field Directional strain, is a bivariate fitting function for thermal strain.

[0079] See Figure 2 The present invention also discloses a thermo-deformation field decoupling system based on two-dimensional vision measurement, comprising:

[0080] The data acquisition module is used to acquire the temperature field, thermal deformation field, temperature field under thermo-mechanical coupling conditions, and deformation field under thermo-mechanical coupling conditions of the material under test at discrete temperatures.

[0081] The influence coefficient fitting module is used to obtain the influence coefficient of the fitting temperature on thermal strain based on the temperature field, the thermal deformation field and the corresponding temperature at discrete temperatures, and using a bivariate function model.

[0082] The module for obtaining the fitted bivariate function model is used to obtain the fitted bivariate function model based on the influence coefficient of the fitted temperature on thermal strain and the bivariate function model.

[0083] The equivalent thermal deformation field acquisition module is used to obtain the equivalent thermal deformation field based on the temperature field under thermo-coupling conditions, the deformation field under thermo-coupling conditions, and the fitted bivariate function model.

[0084] The various modules of the system in this invention work together to significantly improve the decoupling accuracy of the thermo-coupled deformation field, meeting the high-precision requirements of aerospace engine vector nozzles for deformation measurement.

[0085] Example 2:

[0086] See Figure 6 This invention proposes a decoupling method for thermo-mechanical deformation fields based on two-dimensional vision measurement. This method can decompose thermo-mechanically coupled deformation fields more accurately to meet the general accuracy requirements of thermo-mechanically coupled deformation field measurement. The method includes the following steps:

[0087] S1. Design and manufacture a special calibration plate for synchronous calibration of infrared camera and ordinary camera, and build a vision measurement system. The vision system includes a monocular infrared camera 2 for capturing temperature field, a monocular ordinary camera 1 for measuring deformation field, and a special calibration plate for calibrating the internal and external parameters of infrared camera 2 and ordinary camera 1.

[0088] Preferably, step S1 specifically includes:

[0089] S11, a calibration strategy is proposed to simultaneously calibrate infrared camera 2 and ordinary camera 1 using a special calibration plate 4. The base plate of the special calibration plate 4 is made of black material with low infrared reflectivity, and the marker printing paint is made of white paint with high infrared reflectivity to ensure that the markers have good contrast.

[0090] S12, the ordinary camera 1 and the infrared camera 2 are connected using rigid components. The existing crossbeam is selected as the connecting component, and the two cameras are fixed on the crossbeam to ensure that their relative spatial relationship does not change.

[0091] S13, Ordinary camera 1 is equipped with an infrared filter to filter infrared radiation and is used to measure deformation field, while infrared camera 2 receives infrared radiation and is used to measure temperature field.

[0092] S2, acquire images of a specially designed calibration plate, obtain the internal and external parameters of ordinary camera 1 and infrared camera 2 through the acquired images of the specially designed calibration plate, and align the temperature field captured by infrared camera 2 and the deformation field captured by ordinary camera 1 using the marker points in the common field of view.

[0093] Preferably, step S2 specifically includes:

[0094] S21, acquire the image of the special calibration plate. The special calibration plate 4 is illuminated by an infrared light source so that both the infrared camera 2 and the ordinary camera 1 can identify the marker points on the calibration plate.

[0095] S22, based on edge detection algorithm and iterative least squares fitting, performs marker point detection on the acquired calibration board image to obtain the image center coordinates of the marker points;

[0096] S23, using the center coordinates of the marker point images detected by infrared camera 2 and ordinary camera 1, solve for the homography matrix H of the current test area:

[0097]

[0098]

[0099] In the formula: These are the coordinates of the marker points detected by ordinary camera 1. The coordinates of the marker points detected by infrared camera 2. This is a homography matrix used to describe the positional mapping of an object across different coordinate systems. Marker points can be used to align the temperature field with the deformation field. Image of the marker points detected by infrared camera 2 Axis coordinates Image of the marker points detected by infrared camera 2 Axis coordinates , , , , , , and The transformation parameters are the coordinates of the marker points detected by infrared camera 2 to the coordinates of the marker points detected by ordinary camera 1. Image of marker points detected by ordinary camera 1 Axis coordinates Image of marker points detected by ordinary camera 1 Axis coordinates.

[0100] S3, by using an offline hot loading method, calibrates the influence coefficient of the fitting temperature on the thermal strain at different temperature stages of the material, thus eliminating the influence of force;

[0101] Preferably, step S30 specifically includes:

[0102] S31, collect the thermal deformation field and temperature field of the material under discrete temperature, and calculate the influence coefficient of the fitting temperature on the thermal strain under discrete temperature using a bivariate function model based on the thermal deformation field and temperature field.

[0103] S32, Substitute the influence coefficient of the fitted temperature on thermal strain into the bivariate function model to obtain the fitted bivariate function model;

[0104] The formula for obtaining the coefficient of influence of the fitting temperature on thermal strain is as follows:

[0105]

[0106]

[0107]

[0108]

[0109] In the formula: Let the thermal strain be at a certain temperature. To fit the influence coefficient of temperature on thermal strain, Given the temperature difference between two points in time, by expanding the thermo-coupling strain, we can obtain... , as well as Strain increment in the synthesis direction , and Finally, the bivariate function model is substituted into the deformation decoupling equation.

[0110] S4, measure the influence coefficient of the fitted temperature of the applied force load on the thermal strain, and calibrate the deformation field and temperature field of the material offline;

[0111] Preferably, step S4 specifically includes:

[0112] S41: Place the test material with speckled spray within the common field of view of ordinary camera 1 and infrared camera 2, heat the test material and apply a force load, and acquire images of the test material.

[0113] S42: Obtain the deformation field under thermo-coupling conditions by using ordinary camera 1 to capture ordinary camera images of the material under test and using digital image correlation method.

[0114] The temperature field is obtained by using infrared camera 2 to capture infrared images of the material under test and a temperature conversion algorithm.

[0115] S5 decouples the temperature field under the measured thermo-coupling condition, which can decompose the temperature field under the thermo-coupling condition into a thermal deformation field and a load deformation field.

[0116] Preferably, step S50 specifically includes:

[0117] S51: A method for decoupling the thermal deformation field from the load deformation field is proposed to decouple the thermo-mechanical coupled deformation field.

[0118] S52: Substitute the temperature field and initial temperature of the deformable material under test with speckle into the fitted bivariate function model to calculate the equivalent thermal deformation field.

[0119] The load deformation field is separated from the deformation field under thermo-mechanical coupling conditions of the material under test with speckle using an equivalent thermal deformation field. The separation formula is as follows:

[0120]

[0121]

[0122] In the formula: It is a thermo-coupled deformation field. It is the equivalent load deformation field. It is the equivalent thermal deformation field. , and There are three main strains. It is Poisson's ratio, which is a constant;

[0123] The deformation decoupling equation can be used to separate the thermal deformation field and the load deformation field from the deformation field under thermo-mechanical coupling conditions. The final separation formula is as follows:

[0124]

[0125] In the formula: For strain in the x-direction, Strain in the y-direction For shear strain in the xy direction, , , Let x be the strain in the x and y directions and the shear strain in the xy direction of the load deformation field. , For the strain in the x and y directions of the thermal deformation field, is a bivariate fitting function for thermal strain.

[0126] Compared with existing technologies, this invention utilizes the advantages of visual deformation measurement technology based on digital image correlation and infrared thermal imaging technology based on infrared camera 2. By pre-calibrating the influence coefficient of the material's fitting temperature on thermal strain offline, and then simultaneously calibrating the ordinary camera 1 and infrared camera 2 in a thermo-mechanical coupling scenario using a specially designed calibration plate, the thermal deformation can be accurately decomposed from the thermo-mechanical coupling deformation measured by the ordinary camera 1 using the temperature field measured by infrared camera 2 and the pre-calibrated influence coefficient of the fitting temperature on thermal strain. This achieves decoupling of the material's thermo-mechanical deformation, and the visual measurement method provides high measurement accuracy, meeting the measurement needs of industry.

[0127] Example 3:

[0128] like Figure 3 As shown, this embodiment discloses a method for decoupling a thermo-deformation field based on two-dimensional visual measurement, comprising the following five parts:

[0129] S1: Chinese Paladin Figure 4 The system is configured with a visual measurement system including a conventional camera 1 and an infrared camera 2. The conventional camera 1 is equipped with an infrared filter to filter out reflected infrared light sources, and the infrared camera 2 receives infrared light and measures infrared thermal radiation. The conventional camera 1 and the infrared camera 2 are connected together by a rigid crossbeam, and the two cameras are in a relatively static state, forming a visual measurement system. In a specific embodiment, the calibration of the conventional camera 1 and the infrared camera 2 can be completed by a ten-parameter distortion correction model to obtain the intrinsic and extrinsic parameters of the two cameras.

[0130] S2: A special calibration plate is prepared using coatings with different infrared reflectivities. The marker points are made with infrared high reflectivity coatings, and the background area is made with infrared blocking coatings. This ensures that ordinary camera 1 and infrared camera 2 can detect the marker points on the calibration plate at the same time. Then, the homography matrix of the test area is solved by using the image coordinates of the marker points detected by the two cameras, so that the infrared thermal radiation field and deformation field can be aligned.

[0131] In a further embodiment, a method is proposed that can simultaneously calibrate a conventional camera 1 and an infrared camera 2. Marker points are prepared using a coating with high infrared reflectivity, and a background is prepared using a coating with low infrared reflectivity. A filter is used to ensure that the conventional camera 1 can filter out infrared light, while the infrared camera 2 receives infrared light. In this way, both the conventional camera 1 and the infrared camera 2 can detect marker points from the acquired calibration images. The camera's intrinsic and extrinsic parameters are then calibrated using a ten-parameter distortion correction model.

[0132] S3: Apply heat loading to the material at different temperature stages, record the thermal deformation of the material at each discrete temperature point, obtain the continuous thermal deformation curve by fitting the thermal deformation at the discrete points, and establish a fitted bivariate function model.

[0133] In a further embodiment, a method for offline calibration of the influence coefficient of temperature on thermal strain is proposed. Under the condition of only thermal load, thermal loads at different temperature stages are applied to the material to ensure that the material only undergoes thermal deformation. The thermal deformation of the material at different temperature stages is recorded. These discrete thermal deformation data are used to fit a mapping function of the material's thermal deformation with respect to temperature. This mapping function can be used for the next step of thermo-mechanical decoupling.

[0134] S4: Spray high-temperature resistant speckle on the material, and then apply force and heat loads to the material simultaneously. Use ordinary camera 1 to measure the deformation field under thermo-mechanical coupling conditions, and use infrared camera 2 to measure the temperature field under thermo-mechanical coupling conditions.

[0135] In a further embodiment, the material thermal deformation mapping function with respect to temperature established in the previous step can be used to decouple the material's thermo-mechanical coupling deformation field. First, the thermo-mechanical coupling deformation field of the material under thermal and force loads is acquired using a regular camera 1, and the temperature field of the material is acquired using an infrared camera 2. Then, the thermal deformation of the material under the temperature field is obtained using the material thermal deformation field mapping function with respect to temperature. The force deformation field can be obtained by separating the thermal deformation from the thermo-mechanical coupling deformation field, thus completing the decoupling of the thermo-mechanical coupling deformation field.

[0136] S5: First, measure the deformation tensor field, then use the fitted bivariate function model that was calibrated offline in S3, combined with the measured temperature field under thermo-coupling conditions, and the formula for thermo-decoupling to separate the equivalent thermal deformation field from the deformation field under thermo-coupling conditions.

[0137] Example 4:

[0138] like Figures 3 to 7 As shown, this embodiment provides a method for decoupling a thermo-deformation field based on two-dimensional visual measurement, including the following steps:

[0139] S1: The internal and external parameters of the ordinary camera 1 and the infrared camera 2 are obtained by combining the camera distortion model with the special calibration plate 4.

[0140] like Figure 4 As shown, the two-dimensional vision measurement system includes a regular camera 1 on the left, an infrared camera 2 on the right, and a camera connecting beam 3. They form a hybrid binocular camera 12. The field of view of the regular camera 1 is a1, and the field of view of the infrared camera 2 is a2. A special calibration plate 4 and an experimental material sample with speckle spraying are placed within the common field of view of the regular camera 1 and the infrared camera 2.

[0141] During calibration, an infrared filter is installed on the lens of ordinary camera 1 to ensure that the infrared light reflected by the calibration plate is filtered out. The calibration plate is rotated, and ordinary camera 1 and infrared camera 2 acquire images of the calibration plate from multiple angles. Edge extraction, ellipse fitting, and marker center detection are then performed. Finally, the internal and external parameters of ordinary camera 1 and infrared camera 2 are calibrated using a ten-parameter distortion correction model.

[0142] S2: Align the infrared thermal radiation field and the thermo-coupled deformation field using infrared markers.

[0143] S21: Use a coating with high infrared reflectivity to prepare coded and non-coded markers on the calibration board, and use a material with low infrared reflectivity to prepare the background of the calibration board. When illuminated by an infrared light source, the markers will reflect infrared light, so that the infrared camera 2 can identify the markers.

[0144] like Figure 5 As shown, the hybrid binocular vision measurement system includes a regular camera 1, an infrared camera 2, an infrared light source 6, and a blue light source 7. The two light sources simultaneously illuminate a specially designed calibration plate 4. The calibration plate has coded marker points L1 and non-coded marker points L2. The foreground is made of infrared high reflective coating L3, and the background is made of infrared blocking coating L4. This calibration plate can ensure that both the regular camera 1 and the infrared camera 2 can identify the marker points.

[0145] S23: The homography matrix H, describing the positional mapping relationship of the object between various coordinate systems, can be calculated using the image coordinates of the calibration points detected by ordinary camera 1 and infrared camera 2 according to the following formula:

[0146]

[0147]

[0148] In the formula, These are the coordinates of the marker points detected by ordinary camera 1. The coordinates of the marker points detected by infrared camera 2. As a homography matrix, infrared markers can be used to align the infrared thermal radiation field with the deformation field.

[0149] like Figure 7 As shown, the decoupling of the thermo-mechanical coupling deformation field first requires placing the material under test in a thermal environment and measuring its thermal deformation. Then, the thermal deformation is fitted to obtain a fitted bivariate function model. After that, the deformation of the material under the action of thermo-mechanical coupling load is measured. The deformation caused by the thermal load is separated by the offline calibrated mapping function, thus realizing the decoupling of the thermo-mechanical coupling deformation field.

[0150] S3: Use the influence coefficient of the fitting temperature on thermal strain obtained at discrete temperatures to fit the fitted bivariate function model. The specific steps are as follows:

[0151] The material under test was placed in an environment with only thermal load, and thermal loads of different temperatures were applied to it. The deformation field was measured using a conventional camera 1, and the temperature field was measured using an infrared camera 2. The temperature field and deformation field were aligned using a homography matrix to obtain the thermal deformation corresponding to each temperature. Then, a bivariate function model was used for fitting to obtain the fitted bivariate function model. The formula for calculating the influence coefficient of the fitted temperature on thermal strain is as follows:

[0152]

[0153]

[0154]

[0155]

[0156] In the formula: Let the thermal strain be at a certain temperature. To fit the influence coefficient of temperature on thermal strain, Given the temperature difference between two points in time, by expanding the thermo-coupling strain, we can obtain... , as well as Strain increment in the synthesis direction , and Finally, the bivariate function model is substituted into the deformation decoupling equation.

[0157] S4: After establishing the material temperature and the fitted bivariate function model, the deformation in the actual thermo-mechanical coupling scenario can be decoupled. The specific steps are as follows:

[0158] First, thermal and mechanical loads are applied to the material to be tested. The thermo-mechanical coupling deformation field is measured using a conventional camera 1, and the temperature field is measured using an infrared camera 2. The deformation field and temperature field are aligned using a homography matrix.

[0159] S5: The thermal deformation field corresponding to the above temperature field can be obtained by using the fitted bivariate function model, and the equivalent deformation field can be calculated.

[0160]

[0161]

[0162] In the formula: It is a thermo-coupled deformation field. It is the equivalent load deformation field. It is the equivalent thermal deformation field. , and There are three main strains. It is Poisson's ratio, which is a constant.

[0163] The separation of the thermo-coupled deformation field can then be achieved using the following formula.

[0164]

[0165] In the formula: For strain in the x-direction, Strain in the y-direction For shear strain in the xy direction, , , Let x be the strain in the x and y directions and the shear strain in the xy direction of the load deformation field. , For the strain in the x and y directions of the thermal deformation field, is a bivariate fitting function for thermal strain.

[0166] This invention discloses a method for decoupling a thermo-mechanical deformation field based on two-dimensional vision measurement. The method consists of five main steps: First, the intrinsic and extrinsic parameters of a conventional camera 1 and an infrared camera 2 are obtained using a camera distortion model combined with a specially designed calibration plate 4. Second, the infrared thermal radiation field and the thermo-mechanically coupled deformation field are aligned using infrared markers. Third, the influence coefficient of the material's fitting temperature on thermal strain is calibrated using an offline loading method. Next, the thermo-mechanically coupled deformation field and temperature field are measured in a scene containing infrared markers. Finally, the total measured deformation field is decoupled and decomposed into thermal load deformation and mechanical load deformation. This invention achieves relatively accurate decoupling of the thermo-mechanically coupled deformation field, meeting the general accuracy requirements for material deformation measurement.

[0167] Furthermore, the present invention modifies the conventional calibration board so that the modified calibration board can simultaneously calibrate the ordinary camera 1 and the infrared camera 2, thus simplifying the calibration process.

[0168] Furthermore, the method for offline calibration of the influence coefficient of material fitting temperature on thermal strain proposed in this invention only requires one calibration of the material. After that, the results of offline calibration can be directly used for decoupling the thermo-mechanical coupling deformation field measured on the material without repeated calibration, thus having good reusability.

[0169] An electronic device includes: a processor; a memory for storing computer program instructions; and for implementing a thermo-deformation field decoupling method based on two-dimensional vision measurement when executing the computer program.

[0170] A storage medium storing computer program instructions, which are loaded and executed by a processor, wherein the processor performs a thermo-deformation field decoupling method based on two-dimensional visual measurement.

[0171] A computer program product comprising computer instructions that instruct a computer to execute a thermo-deformation field decoupling method based on two-dimensional visual measurements.

[0172] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media containing computer-usable program code, including but not limited to disk storage, CD-ROM, optical storage, etc.

[0173] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus systems, and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0174] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0175] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0176] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A method for decoupling thermo-deformation fields based on two-dimensional visual measurement, characterized in that, Includes the following steps: The temperature field, thermal deformation field, temperature field under thermo-mechanical coupling conditions, and deformation field under thermo-mechanical coupling conditions of the material under test are obtained at discrete temperatures. Based on the temperature field and thermal deformation field at discrete temperatures, and using a bivariate function model, the influence coefficient of the fitted temperature on thermal strain is obtained. The formula for obtaining the influence coefficient of the fitted temperature on thermal strain is as follows: In the formula: For thermal strain, To fit the influence coefficient of temperature on thermal strain, This represents the temperature difference between two points in time. for Strain increment in direction, for Strain increment in direction, for Strain increment in the synthesis direction For the first time right Influence coefficient, For the first time right Influence coefficient, For the first time right Influence coefficient, For the first Time 1 pair Influence coefficient, For the first time right Influence coefficient, For the first time right Influence coefficient, For the first time right Influence coefficient, For the first Time 1 pair Influence coefficient, For the first Temperature at any moment For the first Temperature at any moment For the first Time and the Average temperature over time; The fitted bivariate function model is obtained based on the influence coefficient of the fitted temperature on thermal strain and the bivariate function model. The equivalent thermal deformation field is obtained based on the temperature field under thermo-coupling conditions, the deformation field under thermo-coupling conditions, and the fitted bivariate function model, including: The equivalent thermal deformation field is obtained based on the temperature field under thermo-coupling conditions and the fitted binary function model. The load deformation field is separated from the deformation field under thermo-mechanical coupling conditions using an equivalent thermal deformation field. The separation formula is as follows: In the formula: for Directional strain, for Directional strain, for Directional shear strain, For the load deformation field Directional strain, For the load deformation field Directional strain, For the load deformation field Directional shear strain, For thermal deformation field Directional strain, For thermal deformation field Directional strain, is a bivariate fitting function for thermal strain.

2. The thermo-deformation field decoupling method based on two-dimensional visual measurement according to claim 1, characterized in that, The temperature field under discrete temperature, the thermal deformation field under discrete temperature, the temperature field under thermal coupling conditions, and the deformation field under thermal coupling conditions are all collected using the same visual measurement system. The visual measurement system includes an infrared camera (2) and a regular camera (1) with fixed relative positions. Before the visual measurement system collects data, the internal and external parameters of the infrared camera (2) and the regular camera (1) are calibrated.

3. The thermo-deformation field decoupling method based on two-dimensional visual measurement according to claim 2, characterized in that, It also includes the following steps: Obtain ordinary camera images of the material under test under thermo-coupling conditions using an ordinary camera (1), and obtain the deformation field under thermo-coupling conditions based on the ordinary camera images of the material under test and the digital image correlation method. Acquire infrared camera images of the material under test under thermo-coupling conditions using infrared camera (2), and obtain the temperature field under thermo-coupling conditions based on the infrared camera images of the material under test and a temperature conversion algorithm.

4. The thermo-deformation field decoupling method based on two-dimensional visual measurement according to claim 2, characterized in that, The calibration of the internal and external parameters of the infrared camera (2) and the ordinary camera (1) includes: Obtain the center coordinates of the infrared camera marker point acquired by the infrared camera (2); Obtain the center coordinates of the ordinary camera marker points acquired by the ordinary camera (1); The internal and external parameters of the ordinary camera (1) and the infrared camera (2) are calibrated using the center coordinates of the ordinary camera marker point and the center coordinates of the infrared camera marker point.

5. A thermo-deformation field decoupling system based on two-dimensional visual measurement, comprising the thermo-deformation field decoupling method based on two-dimensional visual measurement according to any one of claims 1 to 4, characterized in that, include: The data acquisition module is used to acquire the temperature field, thermal deformation field, temperature field under thermo-mechanical coupling conditions, and deformation field under thermo-mechanical coupling conditions of the material under test at discrete temperatures. The influence coefficient fitting module is used to obtain the influence coefficient of the fitting temperature on thermal strain based on the temperature field, the thermal deformation field and the corresponding temperature at discrete temperatures, and using a bivariate function model. The module for obtaining the fitted bivariate function model is used to obtain the fitted bivariate function model based on the influence coefficient of the fitted temperature on thermal strain and the bivariate function model. The equivalent thermal deformation field acquisition module is used to obtain the equivalent thermal deformation field based on the temperature field under thermo-coupling conditions, the deformation field under thermo-coupling conditions, and the fitted bivariate function model.

6. An electronic device, comprising: A processor; a memory, an electronic device for storing computer program instructions; characterized in that, when executing the computer program, it implements the thermo-deformation field decoupling method based on two-dimensional visual measurement as described in any one of claims 1-4.

7. A storage medium storing computer program instructions, characterized in that, When the computer program instructions are loaded and run by the processor, the processor executes the thermo-deformation field decoupling method based on two-dimensional visual measurement as described in any one of claims 1-4.

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