Rail transit vehicle body residual stress detection method and storage medium thereof

Abstract

The invention provides a rail transit vehicle body residual stress detection method and a storage medium thereof.The method comprises the steps that metal material parameters and surface parameters of a to-be-detected vehicle body are obtained, a metal plate is determined according to the metal material parameters, then metal stretching calibration is conducted on the metal plate, and an acoustic elastic coefficient is obtained; the method comprises the following steps: manufacturing a zero-stress calibration test block from a metal plate, detecting and calibrating the zero-stress calibration test block to determine a detection method and process parameters if it is determined that the to-be-detected vehicle body meets the residual stress test requirements according to surface parameters, performing ultrasonic detection on the to-be-detected vehicle body according to the detection method and the process parameters to obtain target ultrasonic parameters, and determining the residual stress of the to-be-detected vehicle body according to the target ultrasonic parameters. And establishing a side wall finite element model of the to-be-tested vehicle body, and simulating a corresponding stress condition and a constraint condition in the side wall finite element model according to the acoustic elastic coefficient and the target ultrasonic parameter so as to determine residual stress distribution of the to-be-tested vehicle body under different working conditions, so that residual stress testing can be accurately and quickly performed on the to-be-tested vehicle body.

Description

Technical Field

[0001] The present application relates to the field of rail transit vehicles, and particularly to a method for detecting residual stress of a rail transit vehicle body and a storage medium therefor. Background Art

[0002] During the machining process, uneven plastic deformation caused by external forces and temperature changes is the main cause of residual stress. The manufacturing process of an aluminum alloy body of a rail transit vehicle involves processes such as extrusion, machining, welding, and post-weld treatment and repair. Each process will introduce new residual stresses. Residual stresses will affect the fatigue, fracture strength, and corrosion resistance of the aluminum alloy body structure of a rail transit vehicle. Therefore, the existence of residual stresses has an important impact on the fatigue life of the vehicle body.

[0003] Currently, the most widely used method for testing residual stress is mainly the X-ray diffraction method. However, due to the unique structure of the aluminum alloy body of a rail transit vehicle and the relatively large size of X-ray detection equipment, etc., X-rays cannot detect the residual stress at some corner positions of the aluminum alloy body. Summary of the Invention

[0004] The main purpose of the embodiments of the present application is to propose a method for detecting residual stress of a rail transit vehicle body and a storage medium therefor, so as to solve the problem that it is difficult for X-ray detection equipment to measure the residual stress at the corner positions of the vehicle body to be measured.

[0005] To achieve the above object, a first aspect of the embodiments of the present application proposes a method for detecting residual stress of a rail transit vehicle body, which is applied to a residual stress detector and includes: Obtain the metal material parameters and surface parameters of the vehicle body to be measured; Determine a metal plate having the same metal material parameters according to the metal material parameters; Perform metal tensile calibration on the metal plate by controlling an electronic tensile tester to obtain the acoustoelastic coefficient corresponding to the metal material parameters; Control a zero-stress metal preparator to fabricate the metal plate into a zero-stress calibration test block, and the zero-stress calibration test block is used as an auxiliary detection object for the vehicle body to be measured under zero stress; Determine whether the vehicle body to be measured meets the requirements for residual stress testing according to the surface parameters; If the vehicle body to be measured meets the requirements for residual stress testing, then control a ultrasonic detector to perform detection calibration on the zero-stress calibration test block to determine the detection method and process parameters for the ultrasonic detector to detect the vehicle body to be measured; Control the ultrasonic detector to perform ultrasonic detection on the vehicle body to be measured according to the detection method and process parameters to obtain target ultrasonic parameters; Establish a finite element model of the side wall of the vehicle body to be tested. According to the acoustoelastic coefficient and the target ultrasonic parameters, simulate the corresponding stress conditions and constraint conditions in the finite element model of the side wall to determine the residual stress distribution of the vehicle body to be tested under different working conditions, and determine the cause of the residual stress according to the residual stress distribution.

[0006] Further, in some embodiments, the target ultrasonic parameters include the first critically refracted longitudinal wave parameter and the second critically refracted longitudinal wave parameter. The ultrasonic detector includes an ultrasonic probe. Inside the ultrasonic probe, there are a piezoelectric wafer and a transmitting ultrasonic wedge block. The piezoelectric wafer is used to transmit and receive ultrasonic waves, and the transmitting ultrasonic wedge is used to convert the critically refracted shear wave parameter into a critically refracted longitudinal wave. Control the ultrasonic detector to perform ultrasonic detection on the vehicle body to be tested to obtain the target ultrasonic parameters, including: Control the ultrasonic probe to be placed on the surface of the vehicle body to be tested; Control the piezoelectric wafer to send ultrasonic waves to the vehicle body to be tested, and receive the critically refracted shear wave parameter and the first critically refracted longitudinal wave parameter refracted by the vehicle body to be tested; Control the transmitting ultrasonic wedge to convert the critically refracted shear wave parameter into the second critically refracted longitudinal wave parameter.

[0007] Further, in some embodiments, according to the acoustoelastic coefficient and the target ultrasonic parameters, simulate the corresponding stress conditions and constraint conditions in the finite element model of the side wall, including: According to the acoustoelastic coefficient and the target ultrasonic parameters, determine the stress parameters of the vehicle body to be tested under fatigue conditions, where the stress parameters include the first stress parameter parallel to the vehicle body weld and the second stress parameter perpendicular to the vehicle body weld; According to the first stress parameter, determine the first fatigue strength parameter parallel to the vehicle body weld; According to the second stress parameter, determine the second fatigue strength parameter perpendicular to the vehicle body weld; According to the first fatigue strength parameter and the second fatigue strength parameter, determine the weld composite fatigue strength utilization coefficient of the vehicle body to be tested; According to the stress parameters and the weld composite fatigue strength utilization coefficient, simulate the corresponding stress conditions and constraint conditions in the finite element model of the side wall.

[0008] Further, in some embodiments, the acoustoelastic coefficient is used to feedback the linear relationship between the residual stress change amount and the critically refracted longitudinal wave. According to the acoustoelastic coefficient and the target ultrasonic parameters, determine the stress parameters of the vehicle body to be tested, including: Perform a multiplication operation on the acoustoelastic coefficient and the first critically refracted longitudinal wave parameter to obtain the first stress parameter; Perform a multiplication operation on the acoustoelastic coefficient and the second critically refracted longitudinal wave parameter to obtain the second stress parameter.

[0009] Further, in some embodiments, the first stress parameter includes a first stress amplitude perpendicular to the vehicle body weld seam and a first allowable stress amplitude perpendicular to the vehicle body weld seam. According to the first stress parameter, a first fatigue strength parameter parallel to the vehicle body weld seam is determined, including: Performing a division operation on the first stress amplitude and the first allowable stress amplitude to obtain a first ratio; Taking the absolute value of the first ratio to obtain the first fatigue strength parameter.

[0010] Further, in some embodiments, the second stress parameter includes a second stress amplitude parallel to the vehicle body weld seam and a second allowable stress amplitude parallel to the vehicle body weld seam. According to the second stress parameter, a second fatigue strength parameter perpendicular to the vehicle body weld seam is determined, including: Performing a division operation on the second stress amplitude and the second allowable stress amplitude to obtain a second ratio; Taking the absolute value of the second ratio to obtain the second fatigue strength parameter.

[0011] Further, in some embodiments, if the vehicle body to be tested does not meet the residual stress test requirements, the surface of the vehicle body to be tested is polished by a pneumatic grinding wheel to make the vehicle body to be tested meet the residual stress test requirements. Among them, the pneumatic grinding wheel includes sandpaper with a mesh number of 200# to 1000#.

[0012] Further, in some embodiments, determining whether the vehicle body to be tested meets the residual stress test requirements according to the surface parameters includes: When the surface parameters indicate that there is a substance affecting the stress test on the surface of the vehicle body to be tested, it is determined that the vehicle body to be tested does not meet the residual stress test requirements; Or, when the surface parameters indicate that there is no substance affecting the stress test on the surface of the vehicle body to be tested, it is determined that the vehicle body to be tested meets the residual stress test requirements. Among them, the substances affecting the stress test include grooves, bumps, welding spatter, rust, and oil stains.

[0013] Further, in some embodiments, determining the cause of the residual stress according to the residual stress distribution includes one of the following: Before the vehicle body to be tested undergoes the welding and assembly process, when the residual stress value in the first target area of the vehicle body to be tested is not zero, it is determined that the cause of the residual stress is that the vehicle body to be tested is extruded in the first target area to generate residual stress; Or, During the welding and assembly process of the vehicle body to be tested, when the residual stress values in the areas of the vehicle body to be tested far from the weld seam are all within the first preset stress range, and the residual stress values in the areas close to the weld seam are all within the second preset stress range, it is determined that the cause of the residual stress is characterized as the generation of residual stress due to the normal welding operation of the vehicle body to be tested. Among them, the first preset stress range is from -200 MPa to 190 MPa, and the second preset stress range is from 100 MPa to 190 MPa; Or, After the welding and assembly process of the vehicle body to be tested, when bulging or sinking occurs in the second target area of the vehicle body to be tested due to the absolute value of the residual stress value being greater than the first preset stress value, it is determined that the cause of the residual stress is characterized as the generation of residual stress due to uneven distribution of welding points near the second target area or incorrect repair operations in the second target area; Among them, the welding and assembly process includes the front welding with fixture process, the front welding fixture removal process, the back welding fixture removal process, and the fixture repair process.

[0014] To achieve the above object, a second aspect of the embodiments of the present application proposes a computer-readable storage medium. The computer-readable storage medium stores a program executable by a processor. When the computer program is executed by the processor, the residual stress detection method of the first aspect of the embodiments is implemented.

[0015] The embodiments of the present application have the following beneficial effects: By obtaining the metal material parameters and surface parameters of the vehicle body to be measured; according to the metal material parameters, determining a metal plate having the same metal material parameters, and then, by controlling an electronic tensile tester to perform metal tensile calibration on the metal plate to obtain the acoustoelastic coefficient corresponding to the metal material parameters, and then, by controlling a zero-stress metal preparer to fabricate the metal plate into a zero-stress calibration test block, which is used as an auxiliary test object of the vehicle body to be measured under zero stress; determining whether the vehicle body to be measured meets the requirements for residual stress testing according to the surface parameters, and if the vehicle body to be measured meets the requirements for residual stress testing, then controlling an ultrasonic detector to perform detection and calibration on the zero-stress calibration test block to determine the detection method and process parameters for the ultrasonic detector to detect the vehicle body to be measured, and according to the detection method and process parameters, controlling the ultrasonic detector to perform ultrasonic detection on the vehicle body to be measured to obtain target ultrasonic parameters; establishing a side wall finite element model of the vehicle body to be measured, and according to the acoustoelastic coefficient and the target ultrasonic parameters, simulating the corresponding stress conditions and constraint conditions in the side wall finite element model to determine the residual stress distribution of the vehicle body to be measured under different working conditions, and determining the cause of the residual stress according to the residual stress distribution, so as to be able to accurately and quickly perform residual stress testing on the vehicle body to be measured, and at the same time can make up for the deficiencies of the X-ray detection method, and has a good detection effect on the welds of the hollow extruded profiles with complex structures at the corners of the vehicle body, and the measurement speed of the ultrasonic method is faster than that of the X-ray diffraction method, which is more suitable for on-site testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is an optional flowchart of a method for detecting residual stress of a rail transit vehicle body provided by an embodiment of the present application; Figure 2 is an optional flowchart of simulating corresponding stress conditions and constraint conditions in a side wall finite element model according to the acoustoelastic coefficient and the target ultrasonic parameters provided by an embodiment of the present application; Figure 3 is provided by an embodiment of the present application Figure 2 in an optional flowchart of step S201; Figure 4 is provided by an embodiment of the present application Figure 2 in an optional flowchart of step S202; Figure 5 is provided by an embodiment of the present application Figure 2 in an optional flowchart of step S203; Figure 6 is another optional flowchart of a method for detecting residual stress of a rail transit vehicle body provided by an embodiment of the present application; Figure 7 is provided by an embodiment of the present application Figure 1An optional flowchart of step S105 in Figure 8 It is a schematic diagram of the side wall finite element model of the rail transit vehicle body provided by the embodiment of the present application; Figure 9 It is a residual stress distribution diagram in the simulated welding and assembly process of the side wall finite element model provided by the embodiment of the present application; Figure 10 It is a schematic diagram of the hardware structure of an electronic device provided by an embodiment of the present application. Detailed implementation manners

[0017] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0018] In the description of the present application, it should be understood that for the orientation description, such as the orientation or positional relationship indicated by up, down, front, back, left, right, etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present application 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 should not be construed as a limitation to the present application.

[0019] It should also be noted that in the description of the present application, the meaning of several is more than one, the meaning of multiple is more than two, greater than, less than, exceeding, etc. are understood as not including the number itself, and above, below, within, etc. are understood as including the number itself. If there is a description of first and second, it is only for the purpose of distinguishing technical features and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence relationship of the indicated technical features.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs. The terms used herein are only for the purpose of describing the embodiments of the present application and are not intended to limit the present application.

[0021] In the description of the present application, the description with reference to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0022] The most widely used method for residual stress testing is mainly the X-ray diffraction method. However, due to the unique structure of the aluminum alloy car body of rail transit vehicles and the relatively large size of X-ray detection equipment, X-rays cannot detect the residual stress at some corner positions of the aluminum alloy car body.

[0023] Based on this, the embodiments of the present application provide a method for detecting residual stress of a rail transit vehicle car body and its storage medium. Through automated management and recording among the first terminal, the second terminal, and the server, it can reduce the management time of the involved tobacco and improve the management efficiency.

[0024] A method for detecting residual stress of a rail transit vehicle car body provided by the embodiments of the present application will be specifically described through the following embodiments.

[0025] Refer to Figure 1 as shown in Figure 1 which is an optional flowchart of the method for detecting residual stress of a rail transit vehicle car body provided by the embodiments of the present application. The method may include but is not limited to steps S101 to S108.

[0026] Step S101: Obtain the metal material parameters and surface parameters of the car body to be tested.

[0027] Among them, the metal material parameters include elastic modulus (characterizing material stiffness), yield strength (critical value of plastic deformation), tensile strength (maximum load-bearing capacity), elongation (ductility), hardness (compression indentation resistance), thermal conductivity (heat transfer efficiency), coefficient of thermal expansion (deformation trend under temperature change), electrical conductivity or resistivity (conductive ability), etc., which are not specifically limited in the present application.

[0028] And the surface parameters include surface roughness (micro-irregularities), texture directionality, surface finish (affecting friction and contact behavior), coating type (such as electroplated coating), reflectivity, glossiness, etc., which are not specifically limited in the present application.

[0029] Step S102: Determine the metal sheet with the same metal material parameters according to the metal material parameters.

[0030] Specifically, the residual stress detector determines the metal sheet with the same metal material parameters according to the metal material parameters. In one implementation, the metal material parameters corresponding to the metal sheet include the material structure sequence of the material with the grade of A6N01S-5T.

[0031] Step S103: Perform metal tensile calibration on the metal sheet by controlling the electronic tensile tester to obtain the acoustoelastic coefficient corresponding to the metal material parameters.

[0032] In one implementation, the residual stress detector applies an axial tensile load to a standard metal sheet specimen by controlling a high-precision electronic tensile tester (such as Instron 5967, equipped with a dynamic force sensor and an extensometer), synchronously collects mechanical parameters such as elastic modulus and yield strength in the stress-strain curve, and simultaneously uses a piezoelectric ceramic sensor (PZT-5H type) and an acoustic emission system (frequency response 10 kHz - 2 MHz, signal-to-noise ratio ≥ 40 dB) to capture the acoustic wave propagation characteristics (longitudinal wave velocity, attenuation coefficient) during the tensile process. By performing time-domain analysis (TOF method) and frequency-domain analysis (FFT transform) to extract effective acoustic signals, based on the linear relationship between wave velocity and stress, the acoustic elasticity coefficient K (unit: m / (s·MPa)) is calculated by least squares fitting, and the stability of the coefficient is verified through repeated tests (deviation ≤ ±2%). Finally, a quantitative mapping model between material mechanical parameters and acoustic elasticity characteristics is established, and then the acoustic elasticity coefficient corresponding to the metal material parameters is obtained.

[0033] It should be noted that the acoustic elasticity coefficient characterizes the relationship between the propagation speed of elastic acoustic waves and stress. The principle of measuring residual stress by ultrasonic critically refracted longitudinal waves is based on the basic principle of acoustic elasticity. When ultrasonic waves propagate in an isotropic medium, the change in ultrasonic wave speed is linearly related to the change in residual stress. When the speed of the critically refracted longitudinal wave increases, it indicates that there is compressive residual stress in the material; conversely, there is tensile residual stress. Under the condition that the material properties are determined, there is a linear relationship between the change in residual stress Δσ and the change in the propagation speed of the critically refracted longitudinal wave Δv, that is, Δσ = KΔv, where K is the acoustic elasticity constant.

[0034] Furthermore, the application of using ultrasonic critically refracted longitudinal waves (LCR waves) to measure residual stress has significant advantages compared to critically refracted shear wave parameters: the propagation direction of its longitudinal wave is consistent with the stress direction, and it has higher response sensitivity to surface and near-surface plane stresses (especially suitable for the detection of biaxial stress fields in isotropic metal materials), and it does not require complex polarization control or anisotropy compensation algorithms, simplifying the equipment configuration and signal interpretation process; at the same time, the energy concentration characteristic of ultrasonic critically refracted longitudinal waves near the material surface makes it less affected by microstructural inhomogeneities (such as grain boundaries, dislocations), and its measurement stability is better than that of shear waves (the wave speed fluctuation range can be controlled within ±0.5%). Combining with the linear calibration model of the acoustic elasticity coefficient (the linear relationship between wave speed and stress is clear), it can quickly realize the quantitative inversion of residual stress, and is especially suitable for non-destructive and high-efficiency (single-point detection time < 30 seconds) stress assessment of large-sized components such as welded joints and rolled plates on-site of rail transit vehicles. While shear waves are easily affected by shear stress coupling and multimodal wave interference in the propagation path, and additional angle correction and dispersion suppression measures need to be introduced, resulting in a high system complexity and limited applicable scenarios (such as only suitable for uniaxial stress analysis in specific orientations).

[0035] Step S104: Control the zero-stress metal preparer to fabricate a zero-stress calibration test block from a metal sheet.

[0036] The zero-stress calibration test block is used as an auxiliary test object for the vehicle body to be measured under zero stress.

[0037] In one implementation, the residual stress detector controls the zero-stress metal preparer to fabricate an initial stress calibration test block from a metal sheet by means of cutting, grinding, etc. Then, the residual stress introduced during the processing is eliminated by combining the synchronous vibration aging process to obtain a zero-stress calibration test block. This zero-stress calibration test block can be used as a reference to calibrate the acoustoelastic coefficient of the ultrasonic critical refraction longitudinal wave (LCR wave) residual stress detection equipment. Its non-destructiveness, high stability, and traceability significantly improve the accuracy and efficiency of stress detection in industrial fields.

[0038] Step S105: Determine whether the vehicle body to be measured meets the requirements for residual stress testing according to the surface parameters.

[0039] Specifically, before performing the residual stress test, it is necessary to evaluate the surface parameters of the vehicle body to ensure that they meet the test requirements. The surface parameters include surface roughness, surface hardness, surface defects, etc. The stability and consistency of these parameters are crucial for obtaining accurate and reliable residual stress test results. For example, the X-ray diffraction method requires that the surface roughness of the vehicle body be within a certain range to ensure that the X-ray can accurately irradiate the material interior and produce a clear diffraction pattern. The ultrasonic method requires that the vehicle body surface has a certain hardness and smoothness to ensure that the propagation path of the ultrasonic wave is not disturbed. In addition, surface defects such as cracks and scratches will also affect the accuracy of the test results. Therefore, it is necessary to determine whether the vehicle body to be measured meets the requirements for residual stress testing according to the surface parameters before the test to ensure that the vehicle body surface meets the conditions required for the test.

[0040] Step S106: If the vehicle body to be measured meets the requirements for residual stress testing, control the ultrasonic detector to detect and calibrate the zero-stress calibration test block to determine the detection method and process parameters for the ultrasonic detector to detect the vehicle body to be measured.

[0041] Specifically, in the field of industrial inspection, an ultrasonic detector is a commonly used non-destructive testing tool for detecting defects and damages inside metal materials. To ensure the accurate and reliable detection results of the ultrasonic detector, precise detection and calibration are required before actual application. This process usually uses a zero-stress calibration test block. By controlling the ultrasonic detector to detect this type of test block, the parameters of the detector can be calibrated, such as sound velocity, probe angle, signal-to-noise ratio, resolution, dynamic range, sensitivity, time gain compensation, etc. At the same time, based on the detection results of the test block, the detection method of the ultrasonic detector when detecting the vehicle body to be tested can be determined, including settings such as detection angle, frequency, gain, focusing position, ultrasonic frequency, etc. In addition, a series of process parameters need to be determined, such as scanning speed, step size, etc. These parameters will directly affect the detection efficiency and accuracy. In this way, it can be ensured that when the ultrasonic detector actually detects the vehicle body, it can accurately identify potential defects and damages, thus ensuring the safety and reliability of the vehicle body.

[0042] Step S107: According to the detection method and process parameters, control the ultrasonic detector to perform ultrasonic detection on the vehicle body to be tested, and obtain target ultrasonic parameters.

[0043] Specifically, during the detection process, evenly apply a coupling agent on the surface of the vehicle body to ensure good contact between the probe and the vehicle body surface. Then, according to the established detection method and process parameters, control the ultrasonic detector to scan on the vehicle body, and record parameters such as sound velocity, sound amplitude, waveform, etc. when the ultrasonic wave propagates inside the vehicle body. These parameters will be used as target ultrasonic parameters for subsequent analysis and evaluation to determine whether there are defects or damages inside the vehicle body, thus ensuring the safety and reliability of the vehicle body.

[0044] Among them, the target ultrasonic parameters include the first critical refraction longitudinal wave parameters and the second critical refraction longitudinal wave parameters. The ultrasonic detector includes an ultrasonic probe, and a piezoelectric wafer and a transmitting ultrasonic wedge block are arranged inside the ultrasonic probe. The piezoelectric wafer is used to emit and receive ultrasonic waves, and the transmitting ultrasonic wedge is used to convert the critical refraction shear wave parameters into critical refraction longitudinal wave parameters.

[0045] It should be noted that in step S107, it may also include but is not limited to steps a to c.

[0046] Step a: Control the ultrasonic probe to be placed on the surface of the vehicle body to be tested; Step b: Control the piezoelectric wafer to send ultrasonic waves to the vehicle body to be tested, and receive the critical refraction shear wave parameters and the first critical refraction longitudinal wave parameters refracted by the vehicle body to be tested; Step c: Control the transmitting ultrasonic wedge to convert the critical refraction shear wave parameters into the second critical refraction longitudinal wave parameters.

[0047] It should be noted that a temperature transmitter and a data acquisition card are provided inside the residual stress detector. The temperature transmitter is used to compensate the test temperature in real time, and the data acquisition card is used to collect the target ultrasonic parameters detected by the ultrasonic detector.

[0048] Step S108: Establish a finite element model of the side wall of the vehicle body to be tested. According to the acoustoelastic coefficient and the target ultrasonic parameters, simulate the corresponding stress conditions and constraint conditions in the finite element model of the side wall to determine the residual stress distribution of the vehicle body to be tested under different working conditions, and determine the cause of the residual stress according to the residual stress distribution.

[0049] Specifically, for the side wall of the vehicle body to be tested, it is first necessary to establish its finite element model, which involves an accurate description of the geometric shape, material properties, and boundary conditions of the vehicle body side wall. After establishing the model, the acoustoelastic coefficient and the target ultrasonic parameters obtained previously will be used. These parameters are crucial for simulating the response of the material under the action of sound waves. By inputting these parameters into the finite element model, the behavior of the vehicle body side wall under different stress conditions and constraint conditions can be simulated. In this way, the residual stress distribution of the vehicle body to be tested under various working conditions can be accurately determined. Further, by a detailed analysis of the residual stress distribution, the cause of the residual stress can be traced and determined, which may include welding and forming processes during manufacturing, or repeated loads experienced during use. This analysis is of great significance for optimizing the vehicle body design and improving its safety and reliability.

[0050] Refer to Figure 2 shown in Figure 2 FIG. is an optional flowchart of simulating the corresponding stress conditions and constraint conditions in the finite element model of the side wall according to the acoustoelastic coefficient and the target ultrasonic parameters provided by the embodiment of the present application. The method may include, but is not limited to, steps S201 to S205.

[0051] Step S201: Determine the stress parameters of the vehicle body to be tested under fatigue conditions according to the acoustoelastic coefficient and the target ultrasonic parameters.

[0052] Among them, the stress parameters include a first stress parameter parallel to the vehicle body weld and a second stress parameter perpendicular to the vehicle body weld.

[0053] Step S202: Determine the first fatigue strength parameter parallel to the vehicle body weld according to the first stress parameter.

[0054] Specifically, determine the first fatigue strength parameter parallel to the vehicle body weld according to the first stress parameter .

[0055] Step S203: Determine the second fatigue strength parameter perpendicular to the vehicle body weld according to the second stress parameter.

[0056] Specifically, according to the second stress parameter, a second fatigue strength parameter perpendicular to the vehicle body weld is determined. .

[0057] Step S204: Determine the weld synthetic fatigue strength utilization factor of the vehicle body to be tested according to the first fatigue strength parameter and the second fatigue strength parameter.

[0058] Specifically, according to the first fatigue strength parameter and the second fatigue strength parameter , determine the weld synthetic fatigue strength utilization factor of the vehicle body to be tested , where the calculation formula of the weld synthetic fatigue strength utilization factor is as follows:

[0059] Among them, among them is the correlation coefficient. In one implementation the value of is 1.

[0060] Step S205: Simulate the corresponding stress conditions and constraint conditions in the side wall finite element model according to the stress parameter and the weld synthetic fatigue strength utilization factor.

[0061] Specifically, by integrating the stress parameter (including residual stress distribution, stress amplitude and allowable stress amplitude) and the weld synthetic fatigue strength utilization factor, a multi-physical field coupling simulation environment is constructed in the side wall finite element model. By defining boundary constraint conditions (such as fixing the degrees of freedom of the support surface UX = UY = UZ = 0, symmetric surface displacement constraints and distributed load application), combined with transient dynamics analysis (time step 0.01s) and fatigue life module, dynamically simulate the stress-strain response of the side wall under alternating loads and the risk area of weld fatigue crack initiation.

[0062] Refer to Figure 3 shown, Figure 3 is an optional flowchart in Figure 2 Step S201 provided by an embodiment of the present application. This method may include but is not limited to steps S301 to S302.

[0063] Step S301: Multiply the acoustoelastic coefficient by the first critical refracted longitudinal wave parameter to obtain the first stress parameter.

[0064] Specifically. The first stress parameter = acoustoelastic coefficient K × the first critical refracted longitudinal wave parameter.

[0065] Among them, the first stress parameter includes the first stress amplitude perpendicular to the vehicle body weld and the first allowable stress amplitude perpendicular to the vehicle body weld .

[0066] Step S302: Multiply the acoustoelastic coefficient by the second critical refracted longitudinal wave parameter to obtain a second stress parameter.

[0067] Specifically, the second stress parameter = the acoustoelastic coefficient K × the second critical refracted longitudinal wave parameter.

[0068] Wherein, the second stress parameter includes a second stress amplitude parallel to the vehicle body weld and a second allowable stress amplitude parallel to the vehicle body weld .

[0069] Referring to Figure 4 shown, Figure 4 is an alternative flowchart of step S202 provided by an embodiment of the present application, and the method may include but is not limited to steps S401 to S402. Figure 2 Step S401: Divide the first stress amplitude by the first allowable stress amplitude to obtain a first ratio.

[0070] Specifically, divide the first stress amplitude

[0071] by the first allowable stress to obtain a first ratio . .

[0072] Step S402: Take the absolute value of the first ratio to obtain a first fatigue strength parameter.

[0073] Specifically, take the absolute value of the first ratio to obtain a first fatigue strength parameter .

[0074] Referring to Figure 5 shown, Figure 5 is an alternative flowchart of step S203 provided by an embodiment of the present application, and the method may include but is not limited to steps S501 to S502. Figure 2 Step S501: Divide the second stress amplitude by the second allowable stress amplitude to obtain a second ratio.

[0075] Specifically, divide the second stress amplitude

[0076] by the second allowable stress to obtain a second ratio . .

[0077] Step S502: Take the absolute value of the second ratio to obtain a second fatigue strength parameter.

[0078] Specifically, take the absolute value of the second ratio Take the absolute value to obtain the second fatigue strength parameter .

[0079] Refer to Figure 6 as shown Figure 6 FIG. is another optional flowchart of the method for detecting residual stress of the car body of a rail transit vehicle provided by an embodiment of the present application. The method may include but is not limited to step S601.

[0080] Step S601: If the car body to be tested does not meet the requirements for residual stress testing, control a pneumatic grinding wheel to polish the surface of the car body to be tested so that the car body to be tested meets the requirements for residual stress testing.

[0081] Among them, the pneumatic grinding wheel includes sandpaper with a mesh number of 200# to 1000#.

[0082] Specifically, if the surface condition of the car body to be tested does not meet the requirements for residual stress testing, appropriate pretreatment is required. One common method is to use a pneumatic grinding wheel to polish the surface of the car body to be tested. Before grinding, it is necessary to evaluate factors such as the surface roughness, hardness, and whether there are defects of the car body to determine whether grinding is required. If it is determined that grinding is needed, the operator will control the pneumatic grinding wheel and polish the surface of the car body evenly according to certain process parameters, such as the rotation speed of the grinding wheel, the grinding pressure, and the moving speed. During the grinding process, it is necessary to ensure that impurities such as the surface oxide layer, oil stain, and rust are removed, while avoiding over-grinding that may cause surface damage or change the geometric dimensions of the car body. After grinding, it is necessary to detect the surface parameters of the car body again to confirm whether it has met the requirements for residual stress testing. Only when the surface condition of the car body meets the test standard can subsequent residual stress testing be carried out to ensure the accuracy and reliability of the test results.

[0083] Refer to Figure 7 as shown Figure 7 is provided by an embodiment of the present application Figure 1 An optional flowchart of step S105 in which the method may include but is not limited to steps S701 to S702.

[0084] Step S701: When the surface parameters indicate that there are substances on the surface of the car body to be tested that affect stress testing, it is determined that the car body to be tested does not meet the requirements for residual stress testing.

[0085] Among them, the substances that affect stress testing include grooves, bumps, welding spatter, rust, and oil stains.

[0086] Specifically, when the surface parameters indicate that there are substances such as grooves, bumps, welding spatter, rust, and oil stains on the surface of the car body to be tested that affect stress testing, it indicates that the car body to be tested does not meet the requirements for residual stress testing.

[0087] Step S702: Alternatively, when the surface parameter indicates that there is no substance affecting the stress test on the surface of the vehicle body to be tested, it is determined that the vehicle body to be tested meets the requirements for residual stress testing.

[0088] Specifically, when the surface parameter indicates that there are no substances such as grooves, bumps, welding spatter, rust, oil stains, etc. affecting the stress test on the surface of the vehicle body to be tested, it indicates that the vehicle body to be tested does not meet the requirements for residual stress testing.

[0089] Optionally, the method for detecting residual stress of the rail transit vehicle body provided in the embodiments of the present application may further include, but is not limited to, steps S801 to S803.

[0090] Step S801: Before the vehicle body to be tested undergoes the welding and assembly process, when the residual stress value in the first target area of the vehicle body to be tested is not zero, it is determined that the cause of the residual stress is characterized by the generation of residual stress due to the vehicle body to be tested being extruded in the first target area.

[0091] Specifically, referring to Figure 8 shown in Figure 8 is a schematic diagram of the side wall finite element model of the rail transit vehicle body provided in the embodiments of the present application. Before the vehicle body to be tested undergoes the welding and assembly process, if the residual stress value in a certain area of the vehicle body to be tested shown in the side wall finite element model is not zero, this indicates that there are internal stresses in this area without external loads. The cause of this residual stress can be attributed to the vehicle body to be tested being extruded in this area. The extrusion process will cause plastic deformation of the material, thereby forming residual stress inside the material. These residual stresses may affect the structural integrity and service life of the vehicle body, so it is necessary to identify and process them before welding and assembly.

[0092] Step S802: Alternatively, during the welding and assembly process of the vehicle body to be tested, when the residual stress values in the areas far from the weld are all within the first preset stress range, and the residual stress values in the areas close to the weld are all within the second preset stress range, it is determined that the cause of the residual stress is characterized by the generation of residual stress due to the normal welding operation of the vehicle body to be tested.

[0093] Among them, the first preset stress range is from -200 MPa to 190 MPa, and the second preset stress range is from 100 MPa to 190 MPa.

[0094] It should be noted that, referring to Figure 9 shown in Figure 9It is the residual stress distribution diagram in the simulation welding assembly process of the side wall finite element model provided by the embodiments of the present application. During the welding process, the uneven distribution of heat will cause local expansion and contraction of the material, thus generating residual stress in the weld area and its surrounding areas. The distribution and magnitude of these stresses are closely related to factors such as welding parameters, welding sequence, and material properties. Under normal welding operations, the areas far from the weld are less affected by heat, so the residual stress values are relatively low and are in the first preset stress range; while the areas close to the weld will undergo large thermal expansion and contraction due to the high temperature effect, resulting in higher residual stress values and being in the second preset stress range. Furthermore, it can be determined that the cause of the residual stress generation is characterized by the generation of residual stress due to the normal welding operation of the vehicle body to be tested.

[0095] Step S803: Or, after the vehicle body to be tested undergoes the welding assembly process, when a second target area in the vehicle body to be tested shows bulging or sinking due to the absolute value of the residual stress value being greater than the first preset stress value, it is determined that the cause of the residual stress generation is characterized by uneven distribution of welding points near the second target area or incorrect repair operations in the second target area resulting in residual stress.

[0096] Specifically, after the vehicle body to be tested completes the welding assembly process, if it is shown in the side wall finite element model that a certain area in the vehicle body to be tested shows bulging or sinking due to the absolute value of the residual stress value being greater than the first preset stress value, this indicates that the residual stress in this area has exceeded the normal bearing range of the material. In this case, it can be determined that the cause of the residual stress generation is characterized by uneven distribution of welding points near this area or incorrect repair operations in this area resulting in residual stress. Uneven distribution of welding points will lead to uneven heat distribution, thus generating uneven shrinkage and expansion during the welding process, and finally forming residual stress. Incorrect repair operations may cause additional stress concentration on the material during the repair process, and these stresses cannot be completely released during the cooling process after welding, thus resulting in deformation phenomena such as bulging or sinking on the material surface.

[0097] It should also be noted that the repair operation will cause the peak value of the residual stress in the area near the weld to increase, and at the same time, the residual compressive stress value of the base material in the area far from the weld will increase.

[0098] Among them, the welding assembly process includes the front welding with fixture process, the front welding fixture removal process, the back welding fixture removal process, and the fixture repair process. Further, after each welding assembly process is completed, the overall level of the residual tensile stress in the side wall weld area increases, and the overall level of the residual stress in the base material area far from the weld also increases.

[0099] An embodiment of the present application further provides an electronic device, which includes a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, the above-mentioned residual stress detection method is implemented. The electronic device can be any intelligent terminal including a mobile phone, a tablet computer, an in-vehicle computer, etc.

[0100] Please refer to Figure 10 , Figure 10 which is a schematic diagram of the hardware structure of an electronic device provided by an embodiment of the present application. The electronic device includes: A processor 1001, which can be implemented by using a general-purpose CPU (Central Processing Unit), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits, etc., and is used to execute relevant programs to implement the residual stress detection method provided by the embodiment of the present application; A memory 1002, which can be implemented in the form of a read-only memory (ROM), a static storage device, a dynamic storage device, or a random access memory (RAM), etc. The memory 1002 can store an operating system and other application programs. When implementing the technical solutions provided by the embodiments of this specification through software or firmware, the relevant program codes are stored in the memory 1002, and the processor 1001 is called to execute the residual stress detection method provided by the embodiment of the present application; An input / output interface 1003, which is used to implement information input and output; A communication interface 1004, which is used to implement communication interaction between this device and other devices, and can implement communication through a wired method (such as USB, network cable, etc.) or through a wireless method (such as a mobile network, WIFI, Bluetooth, etc.); A bus 1005, which transmits information between various components of the device (such as the processor 1001, the memory 1002, the input / output interface 1003, and the communication interface 1004); Among them, the processor 1001, the memory 1002, the input / output interface 1003, and the communication interface 1004 are communicatively connected to each other inside the device through the bus 1005.

[0101] An embodiment of the present application further provides a computer-readable storage medium, which stores a computer program, and when the computer program is executed by a processor, the residual stress detection method provided by the embodiment of the present application is implemented.

[0102] As a non-transitory computer-readable storage medium, the memory can be used to store non-transitory software programs and non-transitory computer-executable programs. In addition, the memory may include high-speed random access memory, and may also include non-transitory memory, such as at least one magnetic disk storage device, a flash memory device, or other non-transitory solid-state storage devices. In some embodiments, the memory may optionally include a memory remotely disposed relative to the processor, and these remote memories can be connected to the processor through a network. Examples of the above network include but are not limited to the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0103] The embodiments described in the embodiments of the present application are for more clearly illustrating the technical solutions of the embodiments of the present application, and do not constitute a limitation on the technical solutions provided by the embodiments of the present application. Those skilled in the art will know that with the evolution of technology and the emergence of new application scenarios, the technical solutions provided by the embodiments of the present application are equally applicable to similar technical problems.

[0104] Those skilled in the art can understand that the technical solutions shown in the figures do not constitute a limitation on the embodiments of the present application, and may include more or fewer steps than those shown in the figures, or combine certain steps, or different steps.

[0105] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, that is, they may be located in one place, or may be distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0106] Those of ordinary skill in the art can understand that all or some of the steps in the methods disclosed above, and the functional modules / units in the systems and devices, can be implemented as software, firmware, hardware, and appropriate combinations thereof.

[0107] The terms "first", "second", "third", "fourth", etc. (if any) in the specification of the present application and the above figures are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present application described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units does not have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0108] It should be understood that in this application, "at least one (item)" means one or more, and "a plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that there can be three relationships. For example, "A and / or B" can mean: only A exists, only B exists, and both A and B exist at the same time. Among them, A and B can be singular or plural. The character " / " generally represents an "or" relationship between the associated objects before and after. "At least one (one)" or a similar expression below refers to any combination of these items, including any combination of single item (one) or plural items (ones). For example, at least one (one) of a, b, or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0109] In several embodiments provided in this application, it should be understood that the disclosed systems and methods can be implemented in other ways. For example, the system embodiments described above are merely illustrative. For example, the division of the above units is only a logical function division. In actual implementation, there can be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling or direct coupling or communication connection to each other can be through some interfaces, and the indirect coupling or communication connection of devices or units can be in electrical, mechanical or other forms.

[0110] The units described above as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they can be located in one place, or they can be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0111] In addition, each functional unit in each embodiment of this application can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above integrated units can be implemented in the form of hardware or in the form of software functional units.

[0112] When the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-accessible storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes multiple instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods of various embodiments of this application. The aforementioned storage medium includes: various media that can store programs, such as USB flash drives, mobile hard disks, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical discs.

[0113] The preferred embodiments of the embodiments of this application have been described above with reference to the accompanying drawings. However, this does not limit the scope of the rights of the embodiments of this application. Any modifications, equivalent replacements, and improvements made by those skilled in the art without departing from the scope and essence of the embodiments of this application shall fall within the scope of the rights of the embodiments of this application.

Claims

1. A method for detecting residual stress of a rail transit vehicle car body, applied to a residual stress detector, characterized in that Including: Obtain the metal material parameters and surface parameters of the vehicle body to be tested; Determine a metal sheet having the same metal material parameters according to the metal material parameters; Carry out metal tensile calibration on the metal sheet by controlling an electronic tensile tester to obtain the acoustoelastic coefficient corresponding to the metal material parameters; Control a zero-stress metal preparator to fabricate the metal sheet into a zero-stress calibration test block, and the zero-stress calibration test block is used as an auxiliary detection object of the vehicle body to be tested under zero stress; Determine whether the vehicle body to be tested meets the requirements for residual stress testing according to the surface parameters; If the vehicle body to be tested meets the requirements for residual stress testing, control an ultrasonic detector to detect and calibrate the zero-stress calibration test block to determine the detection method and process parameters for the ultrasonic detector to detect the vehicle body to be tested; Control the ultrasonic detector to perform ultrasonic detection on the vehicle body to be tested according to the detection method and the process parameters to obtain target ultrasonic parameters; Establish a side wall finite element model of the vehicle body to be tested, and simulate the corresponding stress conditions and constraint conditions in the side wall finite element model according to the acoustoelastic coefficient and the target ultrasonic parameters to determine the residual stress distribution of the vehicle body to be tested under different working conditions, and determine the cause of residual stress according to the residual stress distribution.

2. The residual stress detection method according to claim 1, characterized in that, The target ultrasonic parameters include a first critically refracted longitudinal wave parameter and a second critically refracted longitudinal wave parameter, the ultrasonic detector includes an ultrasonic probe, a piezoelectric wafer and a transmitting ultrasonic wedge block are arranged inside the ultrasonic probe, the piezoelectric wafer is used for transmitting and receiving ultrasonic waves, the transmitting ultrasonic wedge is used to convert the critically refracted shear wave parameter into a critically refracted longitudinal wave, and controlling the ultrasonic detector to perform ultrasonic detection on the vehicle body to be tested to obtain target ultrasonic parameters includes: Control the ultrasonic probe to be placed on the surface of the vehicle body to be tested; Control the piezoelectric wafer to send ultrasonic waves to the vehicle body to be tested, and receive the critically refracted shear wave parameter and the first critically refracted longitudinal wave parameter refracted by the vehicle body to be tested; Control the transmitting ultrasonic wedge to convert the critically refracted shear wave parameter into the second critically refracted longitudinal wave parameter.

3. The residual stress detection method according to claim 2, characterized in that The simulating the corresponding stress conditions and constraint conditions in the side wall finite element model according to the acoustoelastic coefficient and the target ultrasonic parameters includes: Determine the stress parameters of the vehicle body to be tested under fatigue conditions according to the acoustoelastic coefficient and the target ultrasonic parameters, wherein the stress parameters include a first stress parameter parallel to the vehicle body weld and a second stress parameter perpendicular to the vehicle body weld; Determine a first fatigue strength parameter parallel to the vehicle body weld according to the first stress parameter; Determine a second fatigue strength parameter perpendicular to the vehicle body weld according to the second stress parameter; Determine the weld synthetic fatigue strength utilization coefficient of the vehicle body to be tested according to the first fatigue strength parameter and the second fatigue strength parameter; Simulate the corresponding stress conditions and constraint conditions in the side wall finite element model according to the stress parameters and the weld synthetic fatigue strength utilization coefficient.

4. The residual stress detection method according to claim 3, characterized in that, The acoustoelastic coefficient is used to reflect the linear relationship between the change in residual stress and the critically refracted longitudinal wave. Determining the stress parameter of the vehicle body to be measured according to the acoustoelastic coefficient and the target ultrasonic parameter includes: Performing a multiplication operation on the acoustoelastic coefficient and the first critically refracted longitudinal wave parameter to obtain the first stress parameter; Performing a multiplication operation on the acoustoelastic coefficient and the second critically refracted longitudinal wave parameter to obtain the second stress parameter.

5. The residual stress detection method according to claim 3, characterized in that The first stress parameter includes a first stress amplitude perpendicular to the vehicle body weld and a first allowable stress amplitude perpendicular to the vehicle body weld. Determining the first fatigue strength parameter parallel to the vehicle body weld according to the first stress parameter includes: Performing a division operation on the first stress amplitude and the first allowable stress amplitude to obtain a first ratio; Taking the absolute value of the first ratio to obtain the first fatigue strength parameter.

6. The residual stress detection method according to claim 3, wherein The second stress parameter includes a second stress amplitude parallel to the vehicle body weld and a second allowable stress amplitude parallel to the vehicle body weld. Determining the second fatigue strength parameter perpendicular to the vehicle body weld according to the second stress parameter includes: Performing a division operation on the second stress amplitude and the second allowable stress amplitude to obtain a second ratio; Taking the absolute value of the second ratio to obtain the second fatigue strength parameter.

7. The residual stress detection method according to claim 1, characterized in that The method further includes: If the vehicle body to be measured does not meet the residual stress test requirements, surface grinding of the vehicle body to be measured is performed by controlling a pneumatic grinding wheel so that the vehicle body to be measured meets the residual stress test requirements, wherein the pneumatic grinding wheel includes sandpaper with a mesh number of 200# to 1000#.

8. The residual stress detection method according to claim 1, characterized in that Determining whether the vehicle body to be measured meets the residual stress test requirements according to the surface parameter includes: When the surface parameter indicates that there is a substance affecting the stress test on the surface of the vehicle body to be measured, it is determined that the vehicle body to be measured does not meet the residual stress test requirements; Or, when the surface parameter indicates that there is no substance affecting the stress test on the surface of the vehicle body to be measured, it is determined that the vehicle body to be measured meets the residual stress test requirements, wherein the substances affecting the stress test include grooves, bumps, welding spatter, rust, and oil stains.

9. The residual stress detection method according to claim 1, characterized in that Determining the cause of residual stress according to the residual stress distribution includes one of the following: Before the vehicle body to be measured undergoes the welding and assembly process, when the residual stress value in the first target area of the vehicle body to be measured is not zero, it is determined that the cause of residual stress generation is characterized by the generation of residual stress due to the vehicle body to be measured being extruded in the first target area; Or, During the welding and assembly process of the vehicle body to be measured, when the residual stress values in the areas far from the weld of the vehicle body to be measured are all within a first preset stress range, and the residual stress values in the areas close to the weld are all within a second preset stress range, it is determined that the cause of residual stress generation is characterized by the generation of residual stress due to the normal welding operation of the vehicle body to be measured, wherein the first preset stress range is -200 MPa to 190 MPa, and the second preset stress range is 100 MPa to 190 MPa; Or, After the vehicle body to be tested undergoes the welding and assembly process, when a bulge or indentation appears in the second target area of the vehicle body to be tested due to the absolute value of the residual stress value being greater than the first preset stress value, it is determined that the cause of the residual stress is characterized by uneven distribution of welding points near the second target area or incorrect repair operations in the second target area, resulting in residual stress; Among them, the welding and assembly process includes a front solder strip tooling process, a front solder unloading tooling process, a back solder unloading tooling process, and a tooling repair process.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a program executable by a processor, and when the program executable by the processor is executed by the processor, the residual stress detection method according to any one of claims 1 to 9 is implemented.

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