CN118583624B - A fatigue detection system for heterogeneous weld joints of spatially oblique steel plates - Google Patents

Abstract

The invention relates to the technical field of weld fatigue detection, in particular to a fatigue detection system for a space oblique steel plate heterogeneous connection weld, which comprises a data acquisition end, an analysis end and a test end. According to the invention, the three-dimensional data acquisition module is used for acquiring data of heterogeneous connection weld joints of the space skew steel plates to be tested, the three-dimensional laser scanner and the high-definition camera are combined for carrying out omnibearing and high-precision image acquisition, three-dimensional information and surface details of the weld joints can be acquired more accurately, a reliable data base is provided for subsequent analysis and modeling, the three-dimensional model construction module is used for setting a base according to requirements after a three-dimensional model is built according to three-dimensional image data acquired by the three-dimensional data acquisition module, a test piece three-dimensional model is generated, a loading clamp model is designed according to the test piece three-dimensional model, the test piece and a fatigue testing machine are conveniently installed and fixed, the problem of unstable fixation of the test piece during fatigue testing is solved, and the accuracy of test piece fatigue detection is ensured.

Description

A fatigue detection system for heterogeneous weld joints of spatially oblique steel plates

Technical Field

The invention relates to the technical field of weld fatigue detection, and in particular to a fatigue detection system for welds of heterogeneous connections of spatially oblique steel plates.

Background Art

Spatial oblique steel plate heterogeneous connection welds are a type of welded structure with high manufacturing difficulty and complex stress states. Spatial oblique steel plate heterogeneous connection weld details appear frequently in bridge structures, such as the weld connection between the inclined web of the steel box girder and the upper and lower flanges of the steel box girder, the weld connection between the cable-beam anchorage area and the cable tower anchorage area of the cable-stayed bridge or suspension bridge, the node weld connection between the arch rib and the hanger of the arch bridge, and the node connection weld between the diagonal brace and other components of the steel truss bridge. Due to the complexity and diversity of bridge structures, in order to meet the design and manufacturing requirements, it is inevitable to use spatial oblique steel plate heterogeneous weld connection at some node connections with complex stress states and special geometric shapes. This type of weld area is a fatigue-sensitive area in the bridge structure, and quality control needs to be focused on.

At present, the research on the mechanical properties of heterogeneous connections of space oblique steel plates is mainly focused on the mechanical characteristics of heterogeneous systems of space oblique steel plates, mainly including the force transmission path, fatigue of the overall structure of heterogeneous space oblique steel plates, and other issues. One of the key reasons for this is that in order to conduct experimental research on the fatigue properties of heterogeneous connections of space oblique steel plates, it is generally necessary to consider full-scale fatigue tests, which are large-scale, costly, and have great safety issues. If fatigue tests are conducted on small-sized specimens, there will be problems such as the variety of specimen designs that are difficult to compare with each other, the design of specimen structures and loading methods that are difficult to restore the stress state of the original bridge structure details, the high production requirements of small specimens, and the easy production errors, and how to evaluate the fatigue performance of specimens through measurement point arrangement and data processing, etc.

Therefore, in order to solve the above problems, a fatigue detection system for heterogeneous connection welds of spatial oblique steel plates is proposed.

Summary of the invention

The purpose of the present invention is to provide a fatigue detection system for heterogeneous connection welds of spatially oblique steel plates to solve the problems raised in the above-mentioned background technology.

To achieve the above object, the present invention provides the following technical solutions:

A fatigue detection system for heterogeneous connection welds of spatial oblique steel plates, comprising:

The data acquisition end includes a three-dimensional data acquisition module and a fatigue monitoring data acquisition module; the three-dimensional data acquisition module acquires three-dimensional image data of the heterogeneous connection welds of the oblique steel plates to be tested; the fatigue monitoring data acquisition module acquires fatigue data of the specimen to obtain fatigue detection data of the specimen;

The analysis end includes a 3D model building module and a fatigue test analysis module;

After receiving the three-dimensional image data of the heterogeneous connection weld of the oblique steel plates to be tested, the three-dimensional model building module establishes a three-dimensional model of the heterogeneous connection weld of the oblique steel plates to be tested according to the three-dimensional image data, designs a base on the three-dimensional model, generates a three-dimensional model of the specimen, and designs a loading fixture model according to the three-dimensional model of the specimen;

The fatigue test analysis module receives the specimen fatigue test data, calculates the fatigue life, evaluates the fatigue damage degree, analyzes the fatigue crack growth trend, and generates a fatigue test analysis report based on the specimen fatigue test data;

The test end includes a specimen processing module and a loading device layout module;

After receiving the three-dimensional model of the specimen, the specimen processing module extracts the size and weld image of the specimen in the three-dimensional model of the specimen, analyzes the weld image, determines the welding method, processes the accessories according to the size of the specimen, and welds according to the determined welding method to obtain the specimen of the heterogeneous connection weld of the spatial oblique steel plates to be tested;

The loading device layout module processes the loading fixture according to the loading fixture model, arranges the loading fixture on the specimen, and uses the fatigue monitoring data acquisition module to collect fatigue data of the specimen.

Preferably, when the three-dimensional data acquisition module acquires three-dimensional images of the specimen, it first uses a three-dimensional laser scanner to acquire three-dimensional contour images of the specimen, and then uses a high-definition camera to acquire all-round images of the specimen.

Preferably, when the three-dimensional model construction module constructs the three-dimensional model of the specimen, it receives the three-dimensional contour image and omnidirectional image data transmitted by the three-dimensional data acquisition module, removes noise and corrects image distortion of the three-dimensional contour image and the omnidirectional image data; uses the three-dimensional contour image data to determine the shape and size of the specimen according to the spatial position information of the point cloud through a point cloud processing algorithm, splices and fuses the point cloud data to construct a preliminary three-dimensional contour model; extracts the color and texture information of the pixels in the omnidirectional image data, maps it to the surface of the three-dimensional contour model, and obtains a three-dimensional model of the heterogeneous connection weld of the spatial oblique steel plates to be tested; determines the direction of the force according to the heterogeneous connection weld of the spatial oblique steel plates to be tested, and then sets a base perpendicular to the direction of the force as a vertical line, splices and fuses the base with the three-dimensional model of the heterogeneous connection weld of the spatial oblique steel plates to be tested, and obtains the three-dimensional model of the specimen.

Preferably, the specimen fatigue detection data collected by the fatigue monitoring data collection module includes strain data, displacement data, loading force data, vibration data, temperature data, acoustic monitoring data and image monitoring data.

Preferably, the fatigue test analysis module receives the fatigue detection data of the specimen, monitors and records the strain data in real time, obtains the strain change curve of the specimen during fatigue loading, analyzes the peak strain, strain amplitude, and strain cycle number of the strain change curve, evaluates the fatigue performance of the specimen, and predicts the fatigue life of the test specimen based on the strain data and the fatigue performance curve of the material; analyzes the displacement data to understand the deformation of the specimen during fatigue loading, the deformation includes the displacement amplitude and the displacement cycle number, generates a displacement curve based on the displacement amplitude and the displacement cycle number, analyzes the change trend of the displacement curve, determines whether the specimen has abnormal deformation or looseness, and evaluates the stiffness change of the specimen and the influence of fatigue damage on the structural performance in combination with the strain data; analyzes the relationship between the loading force and the displacement or strain, and evaluates the mechanical properties of the specimen and fatigue strength; perform spectrum analysis on vibration data to obtain vibration frequency and amplitude, observe changes in vibration frequency, determine whether the specimen has structural looseness or damage, analyze changes in vibration amplitude, and evaluate the degree of fatigue damage of the specimen; monitor the temperature changes of the specimen during fatigue loading, establish a temperature curve, analyze the characteristics of the temperature curve, determine whether the specimen has overheating, and the impact of thermal fatigue on the performance of the specimen, and evaluate the impact of temperature changes on the fatigue life of the specimen; conduct real-time monitoring and analysis of acoustic monitoring data to detect whether the specimen produces abnormal sound during fatigue loading and determine whether the specimen has cracks or damage; perform frame-by-frame analysis of image monitoring data, observe the crack propagation and deformation on the surface of the specimen weld, and evaluate the fatigue damage degree and crack propagation rate of the specimen based on the image analysis results.

Preferably, when determining the welding method of a weld, the acquired weld image is preprocessed, the preprocessing includes denoising, contrast enhancement, and brightness adjustment, and the weld features are extracted from the preprocessed image. The weld features include weld texture, shape, size, position, and groove type. The steel plate material connected by the weld is determined. The steel plate material includes the type, performance, and welding characteristics of the material. The load-bearing capacity, sealing, and corrosion resistance of the specimen are determined considering the use requirements of the welded structure, and the welding method used in the weld image is determined based on the weld characteristics, material analysis, and welding requirements.

Preferably, after the loading device arrangement module completes the arrangement of the loading device, the specimen is installed on a fatigue testing machine to perform a fatigue test on the specimen.

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

The 3D data acquisition module is used to collect data on the heterogeneous connection welds of the oblique steel plates to be tested. The 3D laser scanner and high-definition camera are used to collect images in all directions and with high precision. This can more accurately obtain the 3D information and surface details of the welds, and provide a reliable data basis for subsequent analysis and modeling. The 3D model building module builds a 3D model based on the 3D image data collected by the 3D data acquisition module, sets the base according to the requirements, generates a 3D model of the specimen, and designs a loading fixture model based on the 3D model of the specimen, which facilitates the installation and fixation of the specimen and the fatigue testing machine, and reduces the problem of unstable fixation of the specimen during fatigue testing.

The specimen processing module determines the welding method based on the precise specimen 3D model and weld image analysis, which can improve the welding quality and consistency of the specimen; the fatigue monitoring data acquisition module collects multi-dimensional data including strain, displacement, loading force, vibration, temperature, acoustics and images, so that the fatigue test analysis module can more comprehensively and deeply evaluate the fatigue performance of the specimen. Based on rich data collection and comprehensive analysis, the fatigue test analysis module can more accurately predict the fatigue life of the test specimen and provide an important reference for engineering applications.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the overall structure of a fatigue detection system for heterogeneous connection welds of spatially oblique steel plates according to the present invention;

Fig. 2 is a schematic diagram of the test piece structure of the present invention;

In the figure: 1. base; 2. fixing bolts; 3. test piece; 4. fixture.

DETAILED DESCRIPTION

In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

In the description of the present invention, it is necessary to understand that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise clearly and specifically defined.

In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

Example

Please refer to Figure 1, this embodiment provides a technical solution:

A fatigue detection system for heterogeneous connection welds of spatial oblique steel plates comprises a data acquisition end, an analysis end and a test end.

Please refer to Figure 1, the data acquisition terminal includes a three-dimensional data acquisition module and a fatigue monitoring data acquisition module;

The 3D data acquisition module acquires 3D image data of the heterogeneous connection welds of the oblique steel plates to be tested. When the 3D data acquisition module acquires 3D images of the specimen, it first uses a 3D laser scanner to acquire 3D contour images of the specimen, and then uses a high-definition camera to acquire all-round images of the specimen.

The fatigue monitoring data acquisition module collects the fatigue data of the specimen to obtain the specimen fatigue detection data. The specimen fatigue detection data collected by the fatigue monitoring data acquisition module includes strain data, displacement data, loading force data, vibration data, temperature data, acoustic monitoring data and image monitoring data;

The analysis end includes a 3D model building module and a fatigue test analysis module;

After receiving the three-dimensional image data of the heterogeneous connection weld of the oblique steel plates to be tested, the three-dimensional model building module establishes a three-dimensional model of the heterogeneous connection weld of the oblique steel plates to be tested according to the three-dimensional image data, designs a base on the three-dimensional model, generates a three-dimensional model of the specimen, and designs a loading fixture model according to the three-dimensional model of the specimen;

Furthermore, when the 3D model building module builds the 3D model of the specimen, it receives the 3D contour image and omnidirectional image data transmitted by the 3D data acquisition module, removes noise and corrects image distortion for the 3D contour image and omnidirectional image data; uses the 3D contour image data, through a point cloud processing algorithm, and according to the spatial position information of the point cloud, determines the shape and size of the specimen, splices and fuses the point cloud data to build a preliminary 3D contour model; extracts the color and texture information of the pixels in the omnidirectional image data, maps it to the surface of the 3D contour model, and obtains the 3D model of the heterogeneous connection weld of the oblique steel plates to be tested; determines the direction of the force according to the heterogeneous connection weld of the oblique steel plates to be tested, and then sets a base perpendicular to the direction of the force as a vertical line, splices and fuses the base with the 3D model of the heterogeneous connection weld of the oblique steel plates to be tested, and obtains the 3D model of the specimen;

The fatigue test analysis module receives the specimen fatigue test data, calculates the fatigue life, evaluates the fatigue damage degree, analyzes the fatigue crack growth trend, and generates a fatigue test analysis report based on the specimen fatigue test data;

Furthermore, the fatigue test analysis module receives the fatigue detection data of the specimen, monitors and records the strain data in real time, obtains the strain change curve of the specimen during fatigue loading, analyzes the peak strain, strain amplitude, and strain cycle number of the strain change curve, evaluates the fatigue performance of the specimen, and predicts the fatigue life of the test specimen based on the strain data and the fatigue performance curve of the material; analyzes the displacement data to understand the deformation of the specimen during fatigue loading, the deformation includes the displacement amplitude and the displacement cycle number, generates a displacement curve based on the displacement amplitude and the displacement cycle number, analyzes the change trend of the displacement curve, determines whether the specimen has abnormal deformation or looseness, and evaluates the stiffness change of the specimen and the influence of fatigue damage on the structural performance in combination with the strain data; analyzes the relationship between loading force and displacement or strain, and evaluates the mechanical properties of the specimen and fatigue strength; perform spectrum analysis on vibration data to obtain vibration frequency and amplitude, observe changes in vibration frequency, determine whether the specimen has structural looseness or damage, analyze changes in vibration amplitude, and evaluate the degree of fatigue damage of the specimen; monitor the temperature change of the specimen during fatigue loading, establish a temperature curve, analyze the characteristics of the temperature curve, determine whether the specimen has overheating, and the impact of thermal fatigue on the performance of the specimen, and evaluate the impact of temperature changes on the fatigue life of the specimen; conduct real-time monitoring and analysis of acoustic monitoring data, detect whether the specimen produces abnormal sound during fatigue loading, and determine whether the specimen has cracks or damage; conduct frame-by-frame analysis of image monitoring data, observe the crack extension and deformation on the surface of the specimen weld, and evaluate the fatigue damage degree and crack extension rate of the specimen based on the image analysis results;

The test end includes a specimen processing module and a loading device layout module;

After receiving the three-dimensional model of the specimen, the specimen processing module extracts the size and weld image of the specimen in the three-dimensional model of the specimen, analyzes the weld image, determines the welding method, processes the accessories according to the size of the specimen, and welds according to the determined welding method to obtain the specimen of the heterogeneous connection weld of the spatial oblique steel plates to be tested;

Further, when determining the welding method of the weld, the acquired weld image is preprocessed, the preprocessing includes denoising, contrast enhancement, and brightness adjustment, and the weld features are extracted from the preprocessed image. The weld features include weld texture, shape, size, position, and groove type. The steel plate material connected by the weld is determined. The steel plate material includes the type, performance, and welding characteristics of the material. The bearing capacity, sealing, and corrosion resistance of the test piece are determined considering the use requirements of the welded structure. The welding method used in the weld image is determined according to the weld features, material analysis, and welding requirements.

The loading device layout module processes the loading fixture according to the loading fixture model, arranges the loading fixture on the specimen, and uses the fatigue monitoring data acquisition module to collect fatigue data of the specimen.

In this embodiment, after the loading device arrangement module completes the arrangement of the loading device, the specimen is installed on the fatigue testing machine to perform fatigue testing on the specimen.

Please refer to Figure 2. In this embodiment, the base 1 is provided with fixing bolts 2 for fixing to the fatigue testing machine; the loading fixture is specifically a fixture 4, a mounting hole is provided on the top of the specimen 3, and the fixture 4 is fixed to the mounting hole of the specimen 3 by bolts.

The fatigue detection method of the heterogeneous connection weld of the spatial oblique steel plates includes the following steps:

1. Data Collection

A 3D laser scanner is used to collect 3D contour images of the test piece of the heterogeneous connection weld of the spatial oblique steel plates to be tested;

Ensure the precision and accuracy of the scanner to obtain clear and accurate contour data;

Use high-definition cameras to collect all-round images of the test piece;

Choose the appropriate shooting angle and lighting conditions to ensure image quality and integrity;

The fatigue monitoring data acquisition module collects the fatigue data of the specimen, including strain data, displacement data, loading force data, vibration data, temperature data, acoustic monitoring data and image monitoring data;

Ensure the normal operation of acquisition equipment and real-time recording of data;

2.3D Model Construction

The three-dimensional model building module receives the three-dimensional contour image and omnidirectional image data from the three-dimensional data acquisition module;

Remove noise and correct image distortion for 3D contour images and omnidirectional image data;

Using the 3D contour image data, through the point cloud processing algorithm, according to the spatial position information of the point cloud, the shape and size of the specimen are determined, the point cloud data are spliced and fused, and a preliminary 3D contour model is constructed;

Extract the color and texture information of pixels in the omnidirectional image data, map it to the surface of the 3D contour model, and obtain the 3D model of the heterogeneous connection weld of the spatial oblique steel plates to be tested;

The force direction is determined according to the heterogeneous connection weld of the oblique steel plates in the space to be tested, and then a base perpendicular to the force direction is set with the vertical line, and the base is spliced and merged with the three-dimensional model of the heterogeneous connection weld of the oblique steel plates in the space to be tested to generate a three-dimensional model of the specimen;

Design the loading fixture model according to the three-dimensional model of the specimen;

3. Fatigue test analysis

The fatigue test analysis module receives the specimen fatigue test data;

Monitor and record strain data in real time, obtain the strain change curve of the specimen during fatigue loading, analyze the peak strain, strain amplitude, and strain cycle number of the strain change curve, evaluate the fatigue performance of the specimen, and predict the fatigue life of the specimen based on the strain data and the fatigue performance curve of the material;

Analyze displacement data to understand the deformation of the specimen during fatigue loading, including displacement amplitude and displacement cycle number. Generate a displacement curve based on the displacement amplitude and displacement cycle number, analyze the change trend of the displacement curve, and determine whether the specimen has abnormal deformation or looseness. Combined with strain data, evaluate the stiffness change of the specimen and the impact of fatigue damage on structural performance;

Analyze the relationship between loading force and displacement or strain, and evaluate the mechanical properties and fatigue strength of the specimen;

Perform spectrum analysis on vibration data to obtain vibration frequency and amplitude, observe changes in vibration frequency, determine whether the specimen has structural looseness or damage, analyze changes in vibration amplitude, and evaluate the degree of fatigue damage of the specimen;

Monitor the temperature change of the test piece during fatigue loading, establish a temperature curve, analyze the characteristics of the temperature curve, determine whether the test piece is overheated, and the impact of thermal fatigue on the performance of the test piece, and evaluate the impact of temperature change on the fatigue life of the test piece;

Real-time monitoring and analysis of acoustic monitoring data to detect whether the test piece produces abnormal sound during fatigue loading and determine whether the test piece has cracks or damage;

Analyze the image monitoring data frame by frame to observe the crack extension and deformation on the weld surface of the specimen. According to the image analysis results, evaluate the fatigue damage degree and crack extension speed of the specimen.

Generate fatigue test analysis report;

4. Specimen Processing

The specimen processing module receives the three-dimensional model of the specimen;

Extract the size and weld image of the specimen from the three-dimensional model of the specimen;

Analyze the weld image and determine the welding method;

Preprocess the acquired weld images, including denoising, contrast enhancement, and brightness adjustment;

Extract weld features from the preprocessed image, such as weld texture, shape, size, position, and groove type;

Determine the steel plate materials for welded joints, including material type, performance and welding characteristics;

Consider the use requirements of the welded structure to determine the load-bearing capacity, sealing, and corrosion resistance of the test piece;

Determine the welding method used in the weld image based on weld characteristics, material analysis and welding requirements;

Process accessories according to the size of the test piece;

Welding is performed according to the determined welding method to obtain a test piece of the heterogeneous connection weld of the spatial oblique steel plates to be tested;

5. Loading device layout

The loading device layout module processes the loading fixture according to the loading fixture model;

Place the loading fixture on the specimen;

Use fatigue monitoring data acquisition module to collect fatigue data of the specimen;

6. Fatigue test

After the loading device layout module completes the layout of the loading device, the specimen is installed on the fatigue testing machine to perform fatigue testing on the specimen.

In this embodiment, the fatigue data of the specimen includes:

Strain data collection:

Paste strain gauges on key parts of the specimen. The strain gauges should be firmly pasted and accurately positioned;

Connect the strain gauge, calibrate and zero the strain gauge;

During the loading process, the strain gauge records the strain data in real time;

Displacement data collection:

Install high-precision displacement sensors, such as laser displacement sensors or linear displacement sensors;

Ensure that the sensor is in good contact with the measuring point of the test piece or maintain an appropriate measuring distance;

The sensor is connected to the data acquisition system to obtain displacement change data in real time;

Loading force data collection:

Install a force sensor, such as a pressure sensor or a tension sensor, on the loading device;

The sensor is connected to the loading control system and the data acquisition system;

During the loading process, the force sensor provides real-time feedback on the magnitude and changes of the loading force;

Vibration data collection:

Install the accelerometer on the specimen and select a suitable installation position to accurately capture vibration information;

The sensor is connected to the vibration analysis instrument;

Start the vibration analysis instrument, set the acquisition frequency and parameters, and record the vibration data;

Temperature data collection:

Use contact or non-contact temperature sensors such as thermocouples, RTDs, or infrared thermometers;

The contact sensor should be in good contact with the test piece surface, and the non-contact sensor should adjust the measuring distance and angle;

The sensor is connected to the temperature data acquisition device to record temperature changes in real time;

Acoustic monitoring data collection:

Arrange the acoustic sensor close to the test piece but avoid affecting the normal state of the test piece;

The acoustic sensor is connected to the audio acquisition device;

The acquisition device sets the appropriate sampling frequency and gain to record the sound data;

Image monitoring data collection:

Install a high-definition camera, adjust the shooting angle and focal length, and ensure that the surface of the test piece is clearly captured;

The camera is connected to the frame grabber and the computer;

Set the acquisition frame rate and image resolution to continuously capture the image changes of the specimen during the test.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims (4)

1. A fatigue detection system of space skew steel plate heterogeneous connection weld joint is characterized in that: comprising the following steps:

the data acquisition end comprises a three-dimensional data acquisition module and a fatigue monitoring data acquisition module; the three-dimensional data acquisition module acquires three-dimensional image data of heterogeneous connecting welds of the skew steel plates in the space to be detected; the fatigue monitoring data acquisition module acquires fatigue data of the test piece to obtain fatigue detection data of the test piece;

the analysis end comprises a three-dimensional model building module and a fatigue test analysis module;

The three-dimensional model construction module receives three-dimensional image data of the heterogeneous connecting weld joint of the space-to-be-tested oblique steel plate, then establishes a three-dimensional model of the heterogeneous connecting weld joint of the space-to-be-tested oblique steel plate according to the three-dimensional image data, designs a base on the three-dimensional model, generates a test piece three-dimensional model, and designs a loading fixture model according to the test piece three-dimensional model;

The fatigue test analysis module receives the test piece fatigue detection data, calculates the fatigue life according to the test piece fatigue detection data, evaluates the fatigue damage degree, analyzes the fatigue crack propagation trend and generates a fatigue test analysis report;

the test end comprises a test piece processing module and a loading device layout module;

After the test piece processing module receives the test piece three-dimensional model, extracting the size and the weld image of the test piece in the test piece three-dimensional model, analyzing the weld image, determining a welding mode, processing accessories according to the size of the test piece, and welding according to the determined welding mode to obtain the test piece of the heterogeneous connecting weld of the space skew steel plate to be tested;

The loading device layout module processes the loading clamp according to the loading clamp model, lays the loading clamp on the test piece, and performs fatigue data acquisition on the test piece by using the fatigue monitoring data acquisition module;

when the three-dimensional data acquisition module acquires a three-dimensional image of a test piece, firstly, acquiring a three-dimensional contour image of the test piece by using a three-dimensional laser scanner, and then acquiring an omnibearing image of the test piece by using a high-definition camera;

when the three-dimensional model building module builds a three-dimensional model of a test piece, receiving three-dimensional contour image and all-dimensional image data transmitted by the three-dimensional data acquisition module, and carrying out noise removal and image distortion correction treatment on the three-dimensional contour image and the all-dimensional image data; determining the shape and the size of a test piece according to the space position information of the point cloud by utilizing the three-dimensional contour image data through a point cloud processing algorithm, and splicing and fusing the point cloud data to construct a preliminary three-dimensional contour model; extracting color and texture information of pixels in the omnibearing image data, and mapping the color and texture information to the surface of a three-dimensional contour model to obtain a three-dimensional model of the heterogeneous connecting weld joint of the space skew steel plate to be detected;

Determining an acting force direction according to the heterogeneous connecting weld joint of the space oblique steel plate to be tested, setting a base perpendicular to the acting force direction by taking the acting force direction as a vertical line, and splicing and fusing the base and the three-dimensional model of the heterogeneous connecting weld joint of the space oblique steel plate to be tested to obtain a test piece three-dimensional model; when the welding mode of the welding seam is determined, preprocessing is carried out on the obtained welding seam image, the preprocessing comprises denoising, contrast enhancement and brightness adjustment, characteristics of the welding seam are extracted from the preprocessed image, the characteristics of the welding seam comprise welding seam textures, shapes, sizes, positions and groove types, steel plate materials connected by the welding seam are determined, the steel plate materials comprise types, performances and welding characteristics of the materials, the bearing capacity, the sealing performance and the corrosion resistance of a test piece are determined in consideration of the use requirement of a welding structure, and the welding mode used in the welding seam image is determined according to the characteristics of the welding seam, the analysis of the materials and the welding requirement.

2. The fatigue detection system for the heterogeneous joint welds of spatially-diagonal steel plates according to claim 1, wherein: the test piece fatigue detection data collected by the fatigue monitoring data collection module comprises strain data, displacement data, loading force data, vibration data, temperature data, acoustic monitoring data and image monitoring data.

3. The fatigue detection system for the heterogeneous joint welds of spatially-diagonal steel plates according to claim 2, characterized in that: the fatigue test analysis module receives test piece fatigue detection data, monitors and records corresponding variable data in real time, acquires a strain change curve of the test piece in the fatigue loading process, analyzes peak strain, strain amplitude and strain cycle times of the strain change curve, evaluates the fatigue performance of the test piece, and predicts the fatigue life of the test piece according to the strain data and the fatigue performance curve of the material; analyzing displacement data, namely knowing deformation conditions of the test piece in the fatigue loading process, wherein the deformation conditions comprise displacement amplitude and displacement cycle times, generating a displacement curve according to the displacement amplitude and the displacement cycle times, analyzing the change trend of the displacement curve, judging whether the test piece is abnormally deformed or loosened, and evaluating the rigidity change of the test piece and the influence of fatigue damage on structural performance by combining the strain data; analyzing the relation between the loading force and displacement or strain, and evaluating the mechanical property and fatigue strength of the test piece; performing frequency spectrum analysis on the vibration data to obtain vibration frequency and amplitude, observing the change of the vibration frequency, judging whether the structure of the test piece is loose or damaged, analyzing the change of the vibration amplitude, and evaluating the fatigue damage degree of the test piece; monitoring the temperature change of the test piece in the fatigue loading process, establishing a temperature curve, analyzing the characteristics of the temperature curve, judging whether the test piece has overheat phenomenon or not, and evaluating the influence of the thermal fatigue on the performance of the test piece, and evaluating the influence of the temperature change on the fatigue life of the test piece; monitoring and analyzing the acoustic monitoring data in real time, detecting whether the test piece generates abnormal sound in the fatigue loading process, and judging whether the test piece has cracks or damages; and analyzing the image monitoring data frame by frame, observing crack expansion and deformation conditions of the weld joint surface of the test piece, and evaluating the fatigue damage degree and crack expansion speed of the test piece according to the image analysis result.

4. The fatigue testing system for heterogeneous joints of spatially-skewed steel sheets according to claim 3, wherein: and after the loading device layout module finishes the layout of the loading device, the test piece is mounted on a fatigue testing machine to carry out the fatigue test of the test piece.