A device and method for detecting fatigue cracks in steel box beams using multi-source heterogeneous information fusion

Abstract

The present invention discloses a multi-source heterogeneous information fusion detection device and method for fatigue cracks in steel box girders, which relates to the field of bridge engineering technology. It comprises: a signal generator, a power amplification module, a uniform field magnetization module, an array magnetic sensor module, a data acquisition card, an infrared thermal imaging module, a visible light imaging module and a detection terminal computer. The present invention integrates electromagnetic two-dimensional images and infrared and visible light imaging results, and has higher reliability than traditional eddy current and visual methods for measuring fatigue cracks in steel box girders; the uniform field magnetization module structure is optimized according to the geometric characteristics of the steel box girder, while improving the local magnetic flux, it avoids the formation of the interval uniform heating field to block the field of view of the infrared and visible light imaging modules; a multi-source heterogeneous information fusion detection method is established, which can be applied to the defect identification of the surface of steel box girders in complex situations.

Description

Technical Field

[0001] The present invention relates to the technical field of bridge engineering, and in particular to a device and method for detecting fatigue cracks of a steel box girder using multi-source heterogeneous information fusion. Background Art

[0002] Steel box girders are favored by engineers due to their light weight, high torsional stiffness, and easy fabrication and construction. They are widely used in cable-stayed and suspension bridges. However, as the operating time continues to increase, the increasingly prominent steel box girder defects will bring more challenges to bridge maintenance. Under the combined effects of environmental factors and external loads, fatigue cracks can easily lead to sudden structural damage. Under the action of external loads or oxidation filling, early fatigue cracks appear as closed cracks, which are relatively hidden and difficult to detect. Therefore, mastering the fatigue crack detection method of steel box girders, especially the multi-source heterogeneous information fusion non-destructive testing method that can compensate for the information uncertainty of a single sensor in the crack detection and identification process, is an important prerequisite for box girder maintenance and ensuring the safe service of long-span bridges. It has guiding significance and reference value for the future application of bridge inspection engineering.

[0003] Currently, fatigue crack detection in steel box girders primarily relies on eddy current or visual methods. Eddy current testing is subject to probe lift-off effects, while visual methods suffer from low detection efficiency. Other nondestructive surface defect detection methods, such as optical imaging, are affected by light intensity and the material's surface condition. Eddy current thermal imaging can record the temperature distribution of surface and near-surface cracks in metal materials and can detect early-stage closed fatigue cracks. However, there are issues with non-uniform heating and obstruction of the thermal imager's field of view by the excitation coil.

[0004] Therefore, it is an urgent problem for those skilled in the art to propose a multi-source heterogeneous information fusion detection device and method for fatigue cracks in steel box girders to solve the difficulties existing in the prior art. Summary of the Invention

[0005] In view of this, the present invention provides a multi-source heterogeneous information fusion detection device and method for fatigue cracks in steel box girders, which can simultaneously carry out electromagnetic, eddy current thermal imaging, and optical image quantitative detection and evaluation of fatigue cracks on the surface of steel box girders in a specific area in one detection, fully reflecting the fatigue crack distribution of the scanning path, and realizing efficient and non-destructive detection and evaluation of fatigue cracks in bridge steel box girders.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A multi-source heterogeneous information fusion detection device for fatigue cracks in steel box beams, comprising: a signal generator, a power amplification module, a uniform field magnetization module, an array magnetic sensor module, a data acquisition card, an infrared thermal imaging module, a visible light imaging module and a detection terminal computer; wherein,

[0008] Signal generator, used to set high-frequency signal;

[0009] The power amplifier module is used to amplify the high-frequency signal output by the signal generator to form a high-frequency alternating current signal;

[0010] The uniform field magnetization module is placed on the surface of the steel box girder plate to be tested, and is used to pass a high-frequency AC signal through the sensor coil to generate an induced magnetic field, thereby forming a uniform heating field on the surface of the steel box girder plate to be tested;

[0011] The array magnetic sensor module is located in the uniform heating field formed by the uniform field magnetization module and is used to characterize the distribution difference of electromagnetic signal information of surface defects of the steel box girder plate to be detected;

[0012] Data acquisition card, used to transmit the recorded defect electromagnetic signal information to the detection terminal computer;

[0013] The infrared thermal imaging module is arranged above the surface of the steel box girder plate to be inspected, and is used to record the surface temperature information of the steel box girder plate to be inspected and transmit it to the inspection terminal computer;

[0014] A visible light imaging module is provided above the surface of the steel box girder plate to be inspected, and is used to record optical information of the surface of the steel box girder plate to be inspected and transmit it to the inspection terminal computer;

[0015] The detection terminal computer is used to receive electromagnetic signal information, temperature information and optical information of surface defects of the steel box girder plate to be detected, so as to realize accurate detection of fatigue cracks on the surface of the steel box girder plate to be detected.

[0016] In the above device, optionally, the array magnetic sensor module includes n coils containing ferrite cores, n≥4, and during the detection process, the uniform field magnetization module and the array magnetic sensor module are in non-contact with the surface of the steel box girder plate to be detected.

[0017] In the above device, optionally, the electromagnetic signal information and temperature information of the surface defects of the steel box girder plate to be detected have the same excitation generation source and can be coupled at the physical end. During the detection, the influence of the inspection speed on the heat diffusion is considered. At this time, the diffusion equation of the interval uniform heating field of the uniform field magnetization module is expressed as:

[0018]

[0019] Where ρ is the material density of the steel box girder, C p is the specific heat capacity of the steel box girder material, λ is the heat transfer coefficient, v is the inspection speed, T is the temperature field distribution function, σ is the electrical conductivity of the steel box girder, J e is the eddy current density, and t is the heat diffusion time.

[0020] The above device can optionally analyze the magnetic flux variation law of the induced magnetic field in the uniform field magnetization module by constructing a magnetic circuit model. The magnetic potential F is expressed as:

[0021] F=Φ·R=Φ1·R1+Φ2·R2

[0022] Φ1=Φ 11 +Φ 12

[0023] Φ2=Φ 21 +Φ 22

[0024] The magnetic resistance R of the magnetic circuit is related to the path length l through which the magnetic flux passes, the magnetic permeability μ of the material, and the effective transverse area A through which the magnetic flux flows in the path, that is:

[0025] R=l / μ·A

[0026] Therefore, the partial reluctance of the uniform field magnetization module is expressed as:

[0027] R1=R core1 +R Air1

[0028] R2=R core2 +R Air2 +R s

[0029] Since the magnetic permeability of the yoke is greater than that of the air and the specimen, the magnetic flux of the specimen is greater than that of other parts. When the lift-off height of the uniform field magnetization module is not 0, the excitation effect on the surface of the steel box girder decays with the increase of the lift-off height.

[0030] Among them, Φ is the total magnetic flux generated by the coil with high-frequency current, Φ1 is the magnetic flux generated by the first part of the coil, which can characterize the magnetic flux distribution of the overall structure, Φ2 is the magnetic flux generated by the second part of the coil, and Φ 11 is the magnetic flux of the upper yoke structure, Φ 12 is the magnetic flux passing through the yoke structure to the object being tested, R core1 is Φ 11 The magnetic resistance of the yoke in the flux path, R Air1 is Φ 11 Air gap reluctance; R core2 is Φ 12 The magnetic resistance of the yoke in the flux path, R Air2 is Φ 12 Air gap reluctance, R s is the magnetic resistance in the steel box beam specimen. Since the relative position of the yoke and the induction coil is fixed, R Air1 No change R Air2 It will change with the change of lift.

[0031] A method for detecting fatigue cracks of a steel box girder using multi-source heterogeneous information fusion is provided. A device for detecting fatigue cracks of a steel box girder using multi-source heterogeneous information fusion is provided that performs any of the above, comprising the following steps:

[0032] Reconstruct electromagnetic two-dimensional images, infrared two-dimensional images and optical images based on line scanning method;

[0033] Perform pixel matching operations on electromagnetic 2D images, infrared 2D images, and optical images;

[0034] The segmentation window size is determined based on the proportion of the crack size in the electromagnetic 2D image, infrared 2D image, and optical image. The electromagnetic 2D image, infrared 2D image, and optical image are divided into a series of background information and crack information according to the window size using the dilution matrix decomposition method, and redundant information is eliminated.

[0035] The decision-level fusion method is used to obtain the likelihood image, which can realize the accurate detection of fatigue cracks on the surface of the steel box girder to be inspected.

[0036] The above method is optional, based on the detection of the array magnetic sensor module, and obtains the magnetic two-dimensional image through the Lagrangian interpolation method;

[0037] Acquire infrared two-dimensional images based on infrared thermal imaging module;

[0038] Acquire optical images based on the visible light imaging module.

[0039] In the above method, optionally, the specific content of performing pixel matching operation on the electromagnetic two-dimensional image, the infrared two-dimensional image and the optical image is:

[0040] Use feature extraction algorithms to identify key points in the image;

[0041] Find the matching feature points in the two images through feature matching algorithm;

[0042] Transform one image into the size and spatial coordinate system of another image so that the two images are geometrically aligned. During the image transformation process, interpolation methods are used to calculate the pixel values ​​at the new position.

[0043] The above steps are repeated until the pixel matching operation of the electromagnetic two-dimensional image, the infrared two-dimensional image and the optical image is completed.

[0044] It can be seen from the above technical solution that, compared with the prior art, the present invention provides a device and method for detecting fatigue cracks in steel box girders using multi-source heterogeneous information fusion, which has the following beneficial effects:

[0045] (1) The present invention combines electromagnetic two-dimensional images with infrared and visible light imaging results, and has higher reliability than traditional eddy current and visual methods for measuring fatigue cracks in steel box girders;

[0046] (2) The uniform field magnetization module structure was optimized based on the geometric characteristics of the steel box girder, which not only improved the local magnetic flux but also avoided the formation of a uniform heating field in the interval that would block the field of view of the infrared and visible light imaging modules.

[0047] (3) A multi-source heterogeneous information fusion detection method was established, which can be applied to the defect identification of steel box girder surfaces in complex situations. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0049] Figure 1 This is a structural block diagram of a multi-source heterogeneous information fusion detection device for fatigue cracks in steel box beams provided by the present invention;

[0050] Figure 2 Schematic diagram of the magnetic circuit model of the uniform field magnetization module provided by the present invention;

[0051] Figure 3 A flow chart for reconstructing electromagnetic two-dimensional images, infrared two-dimensional images, and optical images provided by the present invention;

[0052] Figure 4 A flow chart of a method for detecting fatigue cracks in steel box girders using multi-source heterogeneous information fusion provided by the present invention;

[0053] Figure 5 A schematic top view of the distribution of the induced eddy current field and temperature field during detection provided by the present invention;

[0054] Among them, 1-signal generator, 2-power amplification module, 3-uniform field magnetization module, 4-array magnetic sensor module, 5-data acquisition card, 6-infrared thermal imaging module, 7-visible light imaging module, 8-detection terminal computer, 9-steel box girder plate, 10-crack, 11-induced eddy current, 12-temperature distribution information. DETAILED DESCRIPTION

[0055] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0056] Reference Figure 1 As shown, the present invention discloses a multi-source heterogeneous information fusion detection device for fatigue cracks in steel box beams, comprising: a signal generator 1, a power amplification module 2, a uniform field magnetization module 3, an array magnetic sensor module 4, a data acquisition card 5, an infrared thermal imaging module 6, a visible light imaging module 7 and a detection terminal computer 8; wherein,

[0057] Signal generator 1, used for setting high-frequency signal;

[0058] The power amplifier module 2 is used to amplify the high-frequency signal output by the signal generator 1 to form a high-frequency alternating current signal;

[0059] The uniform field magnetization module 3 is placed on the surface of the steel box girder plate 9 to be tested, and is used to pass the high-frequency AC signal through the sensing coil to generate an induced magnetic field, thereby forming a uniform heating field on the surface of the steel box girder plate 9 to be tested;

[0060] The array magnetic sensor module 4 is located in the interval uniform heating field formed by the uniform field magnetization module 3 and is used to characterize the distribution difference of electromagnetic signal information of surface defects of the steel box girder plate 9 to be detected;

[0061] Data acquisition card 5, used to transmit the recorded defect electromagnetic signal information to the detection terminal computer 8;

[0062] The infrared thermal imaging module 6 is arranged above the surface of the steel box girder plate 9 to be inspected, and is used to record the surface temperature information of the steel box girder plate 9 to be inspected and transmit it to the inspection terminal computer 8;

[0063] A visible light imaging module 7 is provided above the surface of the steel box girder plate 9 to be inspected, and is used to record optical information of the surface of the steel box girder plate 9 to be inspected and transmit it to the inspection terminal computer 8;

[0064] The detection terminal computer 8 is used to receive electromagnetic signal information, temperature information and optical information of surface defects of the steel box girder plate 9 to be detected, so as to realize accurate detection of fatigue cracks on the surface of the steel box girder plate 9 to be detected.

[0065] Furthermore, the array magnetic sensor module 4 includes n coils containing ferrite cores, n≥4, and during the detection process, the uniform field magnetization module 3 and the array magnetic sensor module 4 are in non-contact with the surface of the steel box girder plate 9 to be detected.

[0066] Furthermore, the electromagnetic signal information and temperature information of the surface defects of the steel box girder plate 9 to be detected have the same excitation generation source and can be coupled at the physical end. The influence of the inspection speed on the heat diffusion is considered during the detection. At this time, the diffusion equation of the interval uniform heating field of the uniform field magnetization module 3 is expressed as:

[0067]

[0068] Where ρ is the material density of the steel box girder, C p is the specific heat capacity of the steel box girder material, λ is the heat transfer coefficient, v is the inspection speed, T is the temperature field distribution function, σ is the electrical conductivity of the steel box girder, J e is the eddy current density, and t is the heat diffusion time.

[0069] Furthermore, by constructing a magnetic circuit model to analyze the magnetic flux variation law of the induced magnetic field in the uniform field magnetization module 3, the magnetic potential F is expressed as:

[0070] F=Φ·R=Φ1·R1+Φ2·R2

[0071] Φ1=Φ 11 +Φ 12

[0072] Φ2=Φ 21 +Φ 22

[0073] The magnetic resistance R of the magnetic circuit is related to the path length l through which the magnetic flux passes, the magnetic permeability μ of the material, and the effective transverse area A through which the magnetic flux flows in the path, that is:

[0074] R=l / μ·A

[0075] Therefore, the partial reluctance of the uniform field magnetization module 3 is expressed as:

[0076] R1=R core1 +R Air1

[0077] R2=R core2 +R Air2 +R s

[0078] Since the magnetic permeability of the yoke is greater than the magnetic permeability of air and the magnetic permeability of the specimen, the magnetic flux of the specimen is greater than the magnetic flux of other parts. When the lift-off height of the uniform field magnetization module 3 is not 0, the excitation effect on the surface of the steel box girder plate 9 decays as the lift-off height increases.

[0079] Among them, Φ is the total magnetic flux generated by the coil with high-frequency current, Φ1 is the magnetic flux generated by the first part of the coil, which can characterize the magnetic flux distribution of the overall structure, Φ2 is the magnetic flux generated by the second part of the coil, and Φ 11 is the magnetic flux of the upper yoke structure, Φ 12 is the magnetic flux passing through the yoke structure to the object being tested, R core1 is Φ 11 The magnetic resistance of the yoke in the flux path, R Air1 is Φ 11 Air gap reluctance; R core2 is Φ 12 The magnetic resistance of the yoke in the flux path, R Air2 is Φ12 Air gap reluctance, R s is the magnetic resistance in the steel box beam specimen. Since the relative position of the yoke and the induction coil is fixed, R Air1 No change R Air2 It will change with the change of lift.

[0080] In a specific embodiment, the following are included

[0081] The signal generator 1 is connected to the power amplifier module 2 to provide a high-frequency AC driving signal to the uniform field magnetization module 3. A uniformly distributed eddy current field and temperature field are formed within the range of the uniform field magnetization module 3. During the detection process, the uniform field magnetization module 3 and the array magnetic sensor module 4 are lifted off the surface of the steel box girder plate 9 to be detected by 3 mm. When the uniform field magnetization module 3 scans the crack 10 at a fixed detection speed, the eddy current field and temperature field within the range of the uniform field magnetization module 3 are distorted. The array magnetic sensor module 4 consists of four coil structures, distributed on one side of the yoke arm (a part of the uniform field magnetization module 3, not shown in the figure), which is used to record the electromagnetic information of the defect and then supplement the optical image and thermal image information. The shooting direction of the infrared thermal imaging module 6 and the visible light imaging module 7 is facing the surface of the steel box girder plate 9 surrounded by the uniform field magnetization module 3. The output ends of the infrared thermal imaging module 6 and the visible light imaging module 7 are connected to the detection terminal computer 8.

[0082] The electromagnetic signal information and temperature information of the surface defects of the steel box girder plate 9 to be detected have the same excitation generation source and can be coupled at the physical end. The influence of the inspection speed on the heat diffusion is considered during the detection. At this time, the diffusion equation of the interval uniform heating field of the uniform field magnetization module 3 is expressed as:

[0083]

[0084] Where ρ is the material density of the steel box girder, C p is the specific heat capacity of the steel box girder material, λ is the heat transfer coefficient, v is the inspection speed, T is the temperature field distribution function, σ is the electrical conductivity of the steel box girder, J e is the eddy current density, and t is the heat diffusion time.

[0085] like Figure 2 As shown in the figure, by constructing a magnetic circuit model to analyze the flux change law of the induced magnetic field in the uniform field magnetization module, the magnetic potential F is expressed as:

[0086] F=Φ·R=Φ1·R1+Φ2·R2

[0087] Φ1=Φ 11 +Φ 12

[0088] Φ2=Φ 21 +Φ22

[0089] The magnetic resistance R of the magnetic circuit is related to the path length l through which the magnetic flux passes, the magnetic permeability μ of the material, and the effective transverse area A through which the magnetic flux flows in the path, that is:

[0090] R=l / μ·A

[0091] Therefore, the partial reluctance of the uniform field magnetization module is expressed as:

[0092] R1=R core1 +R Air1

[0093] R2=R core2 +R Air2 +R s

[0094] Since the magnetic permeability of the yoke is greater than that of the air and the specimen, the magnetic flux of the specimen is greater than that of other parts. When the lift-off height of the uniform field magnetization module is not 0, the excitation effect on the surface of the steel box girder decays with the increase of the lift-off height.

[0095] Among them, Φ is the total magnetic flux generated by the coil with high-frequency current, Φ1 is the magnetic flux generated by the first part of the coil, which can characterize the magnetic flux distribution of the overall structure, Φ2 is the magnetic flux generated by the second part of the coil, and Φ 11 is the magnetic flux of the upper yoke structure, Φ 12 is the magnetic flux passing through the yoke structure to the object being tested, R core1 is Φ 11 The magnetic resistance of the yoke in the flux path, R Air1 is Φ 11 Air gap reluctance; R core2 is Φ 12 The magnetic resistance of the yoke in the flux path, R Air2 is Φ 12 Air gap reluctance, R s is the magnetic resistance in the steel box beam specimen. Since the relative position of the yoke and the induction coil is fixed, R Air1 No change R Air2 It will change with the change of lift.

[0096] In another specific embodiment, the following are included

[0097] In order to improve the scanning efficiency, a rectangular scanning method is used to uniformly detect the steel box girder plate 9. The solid line is the detection route, and the dotted line is the return route. During the scanning process, the array magnetic sensor module 4 inputs the multi-channel electrical signal of the steel box girder plate 9 to the data acquisition card 5 in real time. The mutual inductance between the array probes will cause the test signal to be distorted. Therefore, a high magnetic permeability shielding cover is required around the single detector. The two-dimensional magnetic imaging is obtained through computer software processing. The processing method is shown in FIG. Figure 3 As shown in Figure 2, the interpolation process improves the resolution of the electromagnetic image. Adaptive wavelet separation is used to extract the frequency domain features of the electromagnetic signal, and electromagnetic noise is separated by setting a threshold, thereby improving the imaging quality of the electromagnetic image.

[0098] The present invention is simulated by using multi-physics finite element simulation analysis method. The simulation analysis results of the surface crack detection of steel box girder plate 9 are as follows: Figure 5 As shown, uniformly distributed induced eddy currents 11 and temperature distribution information 12 exist within the range of uniform field magnetization module 3. The eddy current field distribution around crack 10 on steel box girder plate 9 is affected by crack 10 and gathers at the two endpoints of crack 10, forming a localized high temperature distribution. The verification results demonstrate the feasibility of the present invention.

[0099] and Figure 1 Corresponding to the above device, the embodiment of the present invention also provides a method for detecting fatigue cracks of steel box beams by multi-source heterogeneous information fusion, the flow chart of which is as follows: Figure 4 As shown, the following steps are included:

[0100] Reconstruct electromagnetic two-dimensional images, infrared two-dimensional images and optical images based on line scanning method;

[0101] Perform pixel matching operations on electromagnetic 2D images, infrared 2D images, and optical images;

[0102] The segmentation window size is determined based on the proportion of the crack size in the electromagnetic 2D image, infrared 2D image, and optical image. The electromagnetic 2D image, infrared 2D image, and optical image are divided into a series of background information and crack information according to the window size using the dilution matrix decomposition method, and redundant information is eliminated.

[0103] The decision-level fusion method is used to obtain the likelihood image, which can realize the accurate detection of fatigue cracks on the surface of the steel box girder to be inspected.

[0104] Furthermore, based on the detection of the array magnetic sensor module, a two-dimensional magnetic image is obtained through the Lagrange interpolation method;

[0105] Acquire infrared two-dimensional images based on infrared thermal imaging module;

[0106] Acquire optical images based on the visible light imaging module.

[0107] Furthermore, the specific contents of the pixel matching operation for the electromagnetic two-dimensional image, the infrared two-dimensional image and the optical image are as follows:

[0108] Use feature extraction algorithms to identify key points in the image;

[0109] Find the matching feature points in the two images through feature matching algorithm;

[0110] Transform one image into the size and spatial coordinate system of another image so that the two images are geometrically aligned. During the image transformation process, interpolation methods are used to calculate the pixel values ​​at the new position.

[0111] The above steps are repeated until the pixel matching operation of the electromagnetic two-dimensional image, the infrared two-dimensional image and the optical image is completed.

[0112] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0113] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A multi-source heterogeneous information fusion detection device for fatigue cracks in steel box beams, characterized in that: include: Signal generator, power amplifier module, uniform field magnetization module, array magnetic sensor module, data acquisition card, infrared thermal imaging module, visible light imaging module and detection terminal computer; among them, Signal generator, used to set high-frequency signal; The power amplifier module is used to amplify the high-frequency signal output by the signal generator to form a high-frequency alternating current signal; The uniform field magnetization module is placed on the surface of the steel box girder plate to be tested, and is used to pass a high-frequency AC signal through the sensor coil to generate an induced magnetic field, thereby forming a uniform heating field on the surface of the steel box girder plate to be tested; The array magnetic sensor module is located in the uniform heating field formed by the uniform field magnetization module and is used to characterize the distribution difference of electromagnetic signal information of surface defects of the steel box girder plate to be detected; Data acquisition card, used to transmit the recorded defect electromagnetic signal information to the detection terminal computer; The infrared thermal imaging module is arranged above the surface of the steel box girder plate to be inspected, and is used to record the surface temperature information of the steel box girder plate to be inspected and transmit it to the inspection terminal computer; A visible light imaging module is provided above the surface of the steel box girder plate to be inspected, and is used to record optical information of the surface of the steel box girder plate to be inspected and transmit it to the inspection terminal computer; The detection terminal computer is used to receive electromagnetic signal information, temperature information and optical information of surface defects of the steel box girder plate to be detected, so as to realize accurate detection of fatigue cracks on the surface of the steel box girder plate to be detected; The electromagnetic signal information and temperature information of the surface defects of the steel box girder plate to be detected have the same excitation source and can be coupled at the physical end. The influence of the inspection speed on heat diffusion is considered during the inspection. At this time, the diffusion equation of the interval uniform heating field of the uniform field magnetization module is expressed as follows: in, is the material density of the steel box girder, is the specific heat capacity of the steel box girder material, is the heat transfer coefficient, is the inspection speed, is the temperature field distribution function, is the electrical conductivity of the steel box girder, is the eddy current density, is the heat diffusion time; By building a magnetic circuit model to analyze the flux change law of the induced magnetic field in the uniform field magnetization module, the magnetic potential Expressed as: Reluctance of the magnetic circuit The length of the path through which the magnetic flux passes , material magnetic permeability , the effective transverse area of ​​the material through which the magnetic flux flows in the path Related, that is: Therefore, the partial reluctance of the uniform field magnetization module is expressed as: Since the magnetic permeability of the yoke is greater than that of the air and the specimen, the magnetic flux of the specimen is greater than that of other parts. When the lift-off height of the uniform field magnetization module is not 0, the excitation effect on the surface of the steel box girder decays with the increase of the lift-off height. in, It is the total magnetic flux generated by the coil with high-frequency current. It is the magnetic flux generated by the first part of the coil, which can characterize the magnetic flux distribution of the overall structure. is the magnetic flux generated by the second part of the coil, is the magnetic flux of the upper yoke structure, It is the magnetic flux that passes through the yoke structure to the object being tested. yes the reluctance of the yoke in the flux path, yes Air gap reluctance; yes the reluctance of the yoke in the flux path, yes Air gap reluctance, is the magnetic resistance in the steel box beam specimen. Since the relative position of the yoke and the induction coil is fixed, Will not change It will change with the change of lift.

2. The multi-source heterogeneous information fusion detection device for fatigue cracks in steel box beams according to claim 1 is characterized in that: The array magnetic sensor module includes n coils containing ferrite cores, n≥4. During the detection process, the uniform field magnetization module and the array magnetic sensor module are in non-contact with the surface of the steel box girder plate to be detected.

3. A method for detecting fatigue cracks in steel box beams by fusion of multi-source heterogeneous information, characterized in that: The multi-source heterogeneous information fusion detection device for fatigue cracks of a steel box beam according to any one of claims 1 to 2 comprises the following steps: Reconstruct electromagnetic two-dimensional images, infrared two-dimensional images and optical images based on line scanning method; Perform pixel matching operations on electromagnetic 2D images, infrared 2D images, and optical images; The segmentation window size is determined based on the proportion of the crack size in the electromagnetic 2D image, infrared 2D image, and optical image. The electromagnetic 2D image, infrared 2D image, and optical image are divided into a series of background information and crack information according to the window size using the dilution matrix decomposition method, and redundant information is eliminated. The decision-level fusion method is used to obtain the likelihood image, which can realize the accurate detection of fatigue cracks on the surface of the steel box girder to be inspected.

4. A steel box girder fatigue crack multi-source heterogeneous information fusion detection method according to claim 3, characterized in that: Based on the detection of array magnetic sensor modules, a two-dimensional magnetic image is obtained through the Lagrange interpolation method; Acquire infrared two-dimensional images based on infrared thermal imaging module; Acquire optical images based on the visible light imaging module.

5. The method for detecting fatigue cracks of steel box beams by multi-source heterogeneous information fusion according to claim 3 is characterized in that: The specific contents of pixel matching operation for electromagnetic two-dimensional images, infrared two-dimensional images and optical images are as follows: Use feature extraction algorithms to identify key points in the image; Find the matching feature points in the two images through feature matching algorithm; Transform one image into the size and spatial coordinate system of another image so that the two images are geometrically aligned. During the image transformation process, interpolation methods are used to calculate the pixel values ​​at the new position. The above steps are repeated until the pixel matching operation of the electromagnetic two-dimensional image, the infrared two-dimensional image and the optical image is completed.

Images