A bogie frame fault reproduction test method based on actual service working conditions

Abstract

The present application relates to a bogie frame failure reproduction test method based on actual service working conditions, which comprises: according to the defect characteristics of the failure frame, presetting initial defects in the corresponding area of the bogie frame; based on the line dynamic stress test, obtaining the equivalent stress of the failure area, and establishing the corresponding relationship between the TPDS impact equivalent and the equivalent stress of the failure area; combining the actual operation mileage data of the failure frame, the Miner linear cumulative damage criterion and the equal damage principle, converting the line equivalent stress into the bench grading control stress and the cycle number, and forming the bench grading loading spectrum block; through simulating the actual constraint state of the vehicle, installing the constraint on the bogie frame, and determining the loading parameters based on the strain calibration; according to the loading parameters, performing cyclic loading, monitoring the crack propagation state of the defect area, and obtaining the failure reproduction result. The present application provides a test basis for the failure analysis verification and evaluation of the bogie frame through service load equivalence, defect preset matching and failure whole process reproduction.

Description

Technical Field

[0001] This invention relates to a method for reproducing bogie frame faults based on actual service conditions, belonging to the field of fatigue testing technology for running gear structures of rail transit vehicles. Background Technology

[0002] The bogie frame of a bus is a core load-bearing and force-transmitting component. During long-term operation, the cast steel frame is prone to cracking or even fracture in critical areas such as side beams and guide pillars due to casting defects, welding quality, stress concentration, and fatigue accumulation, directly impacting driving safety. After a failure occurs, it is necessary to reproduce the entire process of crack initiation, propagation, and fracture in a laboratory to pinpoint the root cause, propose targeted rectification plans, and optimize design and maintenance standards.

[0003] Existing bogie frame fatigue tests are mainly divided into two categories:

[0004] 1. Standard load fatigue test: Vertical, transverse and longitudinal standard loads are applied according to specifications such as TB3549.1 to assess the static strength and fatigue strength of the structure. However, it does not target specific original defects and actual failure paths, making it difficult to reproduce the evolution process of the current failure.

[0005] 2. Line load spectrum bench test: The load spectrum is compiled based on the dynamic stress test of the line. Multi-channel loads are applied to the bench to more closely resemble the service condition. However, it is a multi-faceted strength verification of intact structures. It does not include an integrated fault reproduction design for casting and welding defects, the relationship between TPDS equivalent and stress, and the mileage and cycle number of equivalent damage.

[0006] However, existing technologies have the following drawbacks:

[0007] 1. Inaccurate defect simulation: The location, shape, size, and corrosion state of the actual fault were not preset, resulting in distorted reproduction.

[0008] 2. Stress and load are out of sync with reality: Standard loads or general spectra are often used, without establishing a correspondence between impact equivalent and equivalent stress based on actual TPDS monitoring data of the vehicle, resulting in a mismatch between load and actual damage.

[0009] 3. The mileage and cycle equivalence are not scientific: The structural life mileage was not accurately converted into bench loading cycles according to the turning wheel cycle maintenance history and the principle of equal damage. The test cycle and damage degree deviated from the actual working conditions.

[0010] 4. Unreasonable constraint loading and stress control: Symmetrical strain calibration of intact and defective sites was not adopted, making it difficult to accurately lock the stress in the defect area. Summary of the Invention

[0011] The technical problem to be solved by this invention is to overcome the shortcomings of existing bogie frame fatigue tests, solve the problem of not being able to accurately reproduce the actual failure evolution of cast steel frames with original defects, and propose a bogie frame failure reproduction test method based on actual service conditions.

[0012] To address the aforementioned technical problems, this invention proposes a bogie frame fault reproduction test method based on actual service conditions, comprising the following steps:

[0013] On a bogie frame of the same model as the faulty frame, based on the location, shape, and size of the faulty frame, an initial defect matching the actual fault is pre-set in the corresponding area of ​​the bogie frame;

[0014] Based on the TPDS impact equivalent data and line dynamic stress test data obtained by the vehicle operation quality dynamic monitoring system, the correspondence between TPDS impact equivalent and fault area equivalent stress is established, and the equivalent stress of the fault area corresponding to different TPDS impact equivalents in actual service is determined based on the correspondence.

[0015] Based on the actual operating mileage data of the faulty structure, combined with the Miner linear cumulative damage criterion and the equal damage principle, the equivalent stress of the faulty area is converted into the graded control stress and corresponding number of cycles in the test bench loading process, forming a bench graded loading spectrum block with the turning wheel cycle as the unit.

[0016] The pre-defected bogie frame is installed on the test bench. The bogie frame is constrained by a clamping method that simulates the actual constraint state of the vehicle. Preloading is performed according to the graded loading spectrum of the bench, and the bench loading parameters are determined based on the symmetrical strain calibration results of the non-destructive area and the defective area.

[0017] The bogie frame was cyclically loaded according to the bench loading parameters, and the crack propagation status of the pre-set defect area was monitored during the loading process. The fault reproduction results were obtained based on the crack propagation status.

[0018] The beneficial effects of this invention are as follows:

[0019] 1. This invention reproduces the original casting and welding defects of the frame, as well as the corrosion state during long-term operation, making the fault reproduction realistic and reliable. The defects, stress, load, and mileage are close to the actual service state throughout the entire process, and the reproduction consistency is high.

[0020] 2. This invention establishes a quantitative mapping between TPDS impact equivalent, line equivalent stress, and bench control stress.

[0021] 3. This invention converts real operating mileage into bench loading cycles through the principle of equal damage, and converts it according to the operation and maintenance history and Miner linearity criterion. The test damage is equivalent to the actual operation, thus achieving damage equivalence and accelerated reproduction.

[0022] 4. This invention eliminates the interference of defect stress concentration on the experiment by symmetrical strain calibration and periodic loading of the spectrum block, making the stress in the defect area controllable and stably reproducing the entire cycle of crack initiation, stable propagation and fracture.

[0023] 5. The testing cycle of this invention is controllable, and faults that occur during long-term use and operation can be reproduced in the laboratory in a short time.

[0024] 6. This invention has strong engineering practicality, directly serving fault tracing, welding repair process improvement, operation and maintenance standard optimization, and structural life extension.

[0025] 7. This invention has a wide range of applications and can be extended to the reproduction and fatigue verification of faults in other cast steel and welded load-bearing structures with original defects. Attached Figure Description

[0026] The invention will now be further described with reference to the accompanying drawings.

[0027] Figure 1 This is a flowchart illustrating the overall process of an example of the present invention.

[0028] Figure 2 This is a diagram showing the dynamic stress measurement points in the fault area of ​​the structure of this invention.

[0029] Figure 3 This is a diagram showing the correspondence between the TPDS equivalent and the equivalent stress in the fault area in this invention.

[0030] Figure 4 This is a schematic diagram of the constraint loading structure of the present invention.

[0031] Figure 5 This is a schematic diagram of the strain gauge arrangement of the present invention.

[0032] Figure 6 This is a schematic diagram of each spectral block in the present invention.

[0033] In the picture:

[0034] 1. Test frame; 2. Simulated shaft; 3. Rigid support; 4. Shaft housing; 5. Steel cylinder; 6. Vertical actuator; A1. One of the dynamic stress test points; A2. Another dynamic stress test point; A3. A third dynamic stress test point; A4. A fourth dynamic stress test point; K1. Strain gauge at the intact stress control point; Q. Pre-set defect; J1. Stress monitoring point at the intact location; J2. Stress monitoring point at the pre-set defect location; F Z 1. Load of intact location; F Z 2. Loads at pre-set defect locations. Detailed Implementation

[0035] The present invention will now be described in detail with reference to the accompanying drawings, which will make the technical approach and operation steps of the present invention clearer.

[0036] like Figure 1 As shown, according to an embodiment of the present invention, a method for bogie frame fault reproduction test based on actual service conditions is provided, including the following steps:

[0037] S1. On a bogie frame of the same model as the faulty frame, based on the location, shape, and size of the faulty frame, an initial defect matching the actual fault is pre-set in the corresponding area of ​​the bogie frame.

[0038] In a preferred embodiment, an initial defect matching the actual fault is pre-set in the corresponding area of ​​the bogie frame, including:

[0039] Based on the location, size, and shape of the defect in the actual faulty frame, a notch corresponding to the actual fault is machined on the surface of the bogie frame.

[0040] The notch was subjected to nitric acid aqueous solution corrosion treatment to simulate the corrosion state caused by long-term operating environment;

[0041] The defects of incomplete fusion are formed by pre-embedding casting sand, setting tungsten rod positioning, and filling with arc welding. The defect area is then ground and repaired to make the pre-set defects consistent with the actual fault defects.

[0042] Specifically, in the same area of ​​the same type of cast steel frame, pre-set unfused and exposed defects according to the location, shape and size of the faulty frame defects to match the actual fault characteristics.

[0043] Furthermore, for defect pre-setting, a notch is ground in the pre-setting area, with the size consistent with the fault defect; long-term operational corrosion is simulated by corrosion with 20% nitric acid aqueous solution for 24 hours; casting sand is pre-embedded; the tungsten rod is positioned and filled by manual arc welding, and the tungsten rod is removed to form an exposed unfused defect; then the weld bead is ground and shaped, and the grinding of the weld bead is required to be smooth and flat. The qualified standard for the pre-setting defect is that the diameter of the tungsten rod is consistent with the diameter of the fault defect, and the length and depth of the pre-setting notch are consistent with the anatomical size of the fault defect.

[0044] It should be noted that the melting point of tungsten rods is much higher than that of welding materials, and the welding materials can be manually pulled out after filling.

[0045] S2. Based on the TPDS impact equivalent data and line dynamic stress test data obtained by the vehicle operation quality dynamic monitoring system, establish the correspondence between TPDS impact equivalent and fault area equivalent stress, and determine the fault area equivalent stress corresponding to different TPDS impact equivalents in actual service based on the correspondence.

[0046] As a preferred implementation, the correspondence between the TPDS impact equivalent and the equivalent stress in the fault region is established, including:

[0047] Acquire dynamic strain data of the frame of the faulty wheel during operation on the faulty track;

[0048] The dynamic strain data is processed by zero drift removal, strain-stress conversion, and rainflow counting to obtain the graded equivalent stress during line operation.

[0049] The graded equivalent stress is fitted with the TPDS impact equivalent data at the corresponding location to obtain a linear correlation model between the TPDS impact equivalent and the equivalent stress.

[0050] Specifically, the relationship between TPDS equivalent and equivalent stress is established. Dynamic stress tests of the frame are performed on the faulty track using faulty wheels or wheels in similar condition to obtain the measured dynamic stress in the faulty area. Combined with the impact equivalent data of the TPDS detection station, a linear correlation model y=kx+b is fitted.

[0051] Wherein, the dependent variable y is the equivalent force. (Unit: MPa); Independent variable x is the TPDS equivalent; K is the slope of the fitted line; b is the intercept of the fitted line.

[0052] The formula for calculating equivalent stress is as follows:

[0053] ;

[0054] in, The total mileage of the dynamic stress test; Total structural lifespan (mileage); This represents the number of cycles corresponding to the fatigue limit. The number of stress cycles corresponding to each stress level; The exponent of the SN curve; For each stress level.

[0055] Furthermore, equivalent stress The method for obtaining the strain is to attach dynamic strain gauges to key parts of the bogie frame, and then connect the strain signals to a data acquisition system inside the carriage via cables. During train operation, strain and time signals at each measuring point are continuously collected. After data processing steps such as zero drift removal, strain-to-stress conversion, and rainflow counting, a graded stress spectrum is obtained, which is the equivalent stress calculation formula mentioned above. and . This can be obtained through the vehicle's odometer; the mileage at the end of the data collection period is subtracted from the mileage at the start of the data collection period.

[0056] It should be noted that the number of cycles corresponding to the fatigue limit The fatigue limit of steel welds, commonly used by the IIW International Institute of Welding, corresponds to 2 million cycles; the exponent of the SN curve. The data is obtained through fatigue performance testing of the material. In accordance with the GB / T 3075-2021 standard, standard specimens of the material are prepared, and axial fatigue tests are performed using an electro-hydraulic servo fatigue testing machine. A series of stress and fatigue life data points are obtained, and then the material SN curve is plotted according to the method specified in the GB / T 24176-2009 standard. The slope of the SN curve is taken as the reciprocal of the m value, which is 3.5 in this embodiment.

[0057] TPDS impact equivalent refers to the wheelset tread impact equivalent obtained by the Vehicle Operation Quality Dynamic Monitoring System (one of the railway 5T safety monitoring systems), abbreviated as TPDS equivalent. TPDS equivalent is a unified indicator for quantifying the degree of damage to the wheel tread. It collects wheel-rail vertical impact load, wheel weight, and train speed in real time, and uses a built-in algorithm to comprehensively calculate a dimensionless equivalent value, uniformly measuring the impact destructive force of all tread defects such as abrasions, peeling, wheel out-of-roundness, and tread pits on the rails and vehicles.

[0058] Furthermore, dynamic stress testing was performed on the faulty wheel or a similar wheel and the faulty track, with the measurement point diagram shown below. Figure 2 As shown, the correspondence between TPDS equivalent and fault area equivalent stress is established, such as... Figure 3 The correspondence between TPDS equivalent and fault area equivalent stress is shown in Table 1.

[0059] Table 1. Correspondence between TPDS equivalent and equivalent stress in the fault area

[0060]

[0061] It should be noted that, Figure 2 The arrows A1, A2, A3, and A4 in the diagram indicate the specific arrangement of the measuring points for the dynamic stress test. Figure 3 The TPDS impact equivalent is a dimensionless parameter with no unit. In this embodiment, there are six TPDS detection stations along the faulty line. Each wheel at each location can obtain a TPDS value at each detection station, and the equivalent stress at the corresponding location's dynamic stress measurement point within the area containing that detection station can be calculated. Since the TPDS values ​​obtained from different detection stations may be the same, different equivalent stresses will occur under the same TPDS equivalent. The average equivalent stress can be taken as the equivalent stress under that TPDS equivalent, thus generating... Figure 3 The eight data points were then subjected to linear fitting.

[0062] S3. Based on the actual operating mileage data of the faulty structure, combined with the Miner linear cumulative damage criterion and the equal damage principle, the equivalent stress of the faulty area is converted into the graded control stress and corresponding number of cycles in the test bench loading process, forming a bench graded loading spectrum block with the turning wheel cycle as the unit.

[0063] As a preferred implementation, the calculation formula combining Miner's linear cumulative damage criterion and the equal damage principle is as follows:

[0064] ;

[0065] in, For each level of equivalent stress; This represents the number of cycles corresponding to the fatigue limit. Total structural lifespan (mileage); Control stress for each stage of the test bench; The number of cycles for the i-th level spectral block; For the first The number of kilometers corresponding to each spectral block. is the exponent of the SN curve.

[0066] It should be noted that the correspondence between TPDS equivalent and mileage during the turning cycle can be determined by extracting the TPDS equivalent data from the last turning of the faulty wheel to the day of the fault. This allows us to establish the relationship between the operating mileage of the faulty structure and the TPDS equivalent within one turning cycle (600,000 kilometers). The test bench control stress is applied at a rate of 1 cycle equal to 1 kilometer. Based on Miner's linear cumulative damage and equal damage principles, the equivalent stress of the line is converted into graded test bench control stress.

[0067] Specifically, by using the TPDS equivalent data monitored by the wheel at the fault location from the last wheel turning to the day of the fault, the correspondence between the operating mileage of the faulty structure and the TPDS equivalent within a wheel turning cycle (600,000 km) can be determined as shown in Table 2, based on a wheel turning cycle of 600,000 km.

[0068] Table 2. Correspondence between the mileage of the faulty wheel and the TPDS equivalent within one turning cycle.

[0069]

[0070] Furthermore, the equal damage equivalent bench control stress and cycle number are calculated using the formula combining Miner's linear cumulative damage criterion and the equal damage principle, as shown in Table 3.

[0071] Table 3 Stress at various control points during bench testing

[0072]

[0073] S4. Install the pre-defected bogie frame on the test bench, constrain the bogie frame by clamping in a way that simulates the actual constraint state of the vehicle, preload according to the graded loading spectrum of the bench, and determine the bench loading parameters based on the symmetrical strain calibration results of the non-destructive area and the defective area.

[0074] As a preferred embodiment, the bogie frame is constrained by a clamping method that simulates the actual constraint state of the vehicle, including:

[0075] The bogie frame is mounted on top of the axle box, and the primary spring support structure of the vehicle is simulated by steel cylinders.

[0076] A simulated axle is used to simulate a vehicle axle, and rigid supports are set in the wheel seat area of ​​the simulated axle to simulate the constraint state of the wheel on the bogie frame;

[0077] The bogie frame is subjected to load by multiple vertical actuators acting on the bogie frame boom seats.

[0078] As a preferred embodiment, the test bench loading parameters are determined based on the symmetrical strain calibration results of the undamaged region and the defective region, including:

[0079] Stress monitoring points are set in the pre-defined defect area, and corresponding stress control points and stress monitoring points are set in the non-destructive area that is symmetrical to the center of the defect area.

[0080] Apply a load to the undamaged area and obtain the corresponding stress response;

[0081] Adjust the load applied to the defective area until the stress response of the stress monitoring point in the defective area is consistent with the stress monitoring point in the undamaged area.

[0082] The bench loading parameters are determined based on the adjusted load applied to the defect area.

[0083] Specifically, such as Figure 4 As shown, the constraint method of the test bench is that the frame is placed in the axle box body by simulating a series of springs through steel cylinders. The axle box body is connected to the tooling simulated shaft through bearings, simulating the rigid support of the axle wheel seat area, and restoring the operating boundary conditions.

[0084] The loading method involves four vertical actuators acting on four boom supports, with the load amplitude determined by the target control stress at the stress control point.

[0085] Figure 4 The test frame 1 (i.e., the bogie frame) is equipped with a simulated axle 2 to simulate the axle of the bogie; a rigid support 3 is installed in the wheel seat area of ​​the simulated axle to simulate wheel constraints; an axle box 4 serves as a support for the primary steel cylinder and a bearing installation; a steel cylinder 5 replaces the primary steel spring support; and a vertical actuator 6 is used for loading.

[0086] Furthermore, for strain gauge placement, strain gauges are symmetrically arranged at intact and defective locations, and the load is calibrated, such as... Figure 5 As shown, Figure 5 In the diagram, K1 is a strain gauge at a intact stress control point symmetrical to the center of the pre-set defect location; Q is the pre-set defect; J1 is a stress monitoring point at an intact location; J2 is a stress monitoring point at a pre-set defect location, symmetrical to J1; F Z 1 represents the load at an intact position (1 vertical load); F Z 2 is the load for the pre-set defect location (1 vertical load).

[0087] For the pre-set defect location, stress control points and strain gauges for stress monitoring points are first arranged at the intact locations symmetrically on the frame. Based on the symmetry of the structure, by applying load Fz1 to the intact locations, the stress control points reach the control stress in Table 3. At this time, the stress level of the stress monitoring points at the intact locations is recorded. At the pre-set defect location, load Fz2 is applied to make the stress level of the same stress monitoring point at that location consistent with the stress monitoring point at the intact location, and the load at the defect location is locked.

[0088] It should be further explained that strain gauges are densely arranged near the pre-set defects and also densely arranged near the stress control points at the center symmetry. Stress monitoring points are found by trial loading so that the stress and position of the stress monitoring points at the defect location and the symmetry location are the same.

[0089] In this embodiment, a total of 22 strain gauges (4 positions) were arranged in the pre-set defect area, and a total of 23 strain gauges were arranged in the symmetrical area of ​​position 1. Finally, the stress control point of position 1 was determined to be 1-M22, the stress monitoring point was determined to be 1-M16, and the stress monitoring point of position 4 was determined to be 4-M16. The applied load and stress response at each position during the experiment are listed in Table 4.

[0090] Table 4 Loading load and stress at stress measurement points for each spectral block

[0091] It should also be noted that the stress error at each stage of the stress control point test does not exceed 5%.

[0092] S5. Perform cyclic loading on the bogie frame according to the bench loading parameters, and monitor the crack propagation status of the pre-set defect area during the loading process. Obtain the fault reproduction result based on the crack propagation status.

[0093] In a preferred embodiment, the bogie frame is cyclically loaded according to the bench loading parameters, including:

[0094] The loading spectrum is divided according to the operating mileage corresponding to the wheel turning cycle of the vehicle;

[0095] According to the number of loading cycles corresponding to the graded control stress, the control stress at each level is cyclically applied;

[0096] Repeatedly executing multiple loading spectrum blocks causes the steering architecture to accumulate fatigue damage corresponding to the actual operation process.

[0097] As a preferred implementation, after each loaded spectrum block is completed, non-destructive testing is performed on the defect area;

[0098] Obtain the crack length and crack propagation state in the defect area;

[0099] Based on the crack length and crack propagation state, the correspondence between the number of loading cycles and the fault evolution process is recorded.

[0100] As a preferred embodiment, the failure reproduction result is obtained based on the crack propagation state, including:

[0101] When the detected crack length reaches the preset crack determination size, stop the cyclic loading of the spectrum block;

[0102] Based on the number of loading cycles, crack length, and crack propagation process at the time of loading cessation, the failure evolution reproduction results during the actual service process of the bogie frame are determined.

[0103] As a preferred implementation, the failure evolution reproduction results include the number of loading cycles corresponding to the crack initiation stage, the crack stable propagation stage, and the fracture failure stage.

[0104] Specifically, the spectral block periodic loading is carried out with a loading block of 600,000 kilometers (one turning wheel cycle), and graded stress spectra are applied cyclically until the structure completely cracks, thus reproducing the real failure evolution.

[0105] Furthermore, the crack propagation monitoring frequency and fracture determination were determined by performing a non-destructive testing on the pre-set defect area after each cycle of the control stress corresponding to each level of the loading spectrum block. The presence and length of cracks were recorded (measured and photographed using a soft measuring tape). The total transverse length of the bottom surface of the inner side of the guide column (fault area) of the frame was 151 mm. When the bottom surface crack propagation length reached 151 mm, complete fracture was determined, the test ended, and the fault reproduction was completed. The fault determination was complete fracture of the frame, the test ended, and the cycle number and crack length were recorded.

[0106] It should be further explained that the spectral loading is performed in 600,000-kilometer increments, with cyclic loading to simulate the wheel maintenance process. Periodic flaw detection monitors cracks and records the cycle number and crack length. For example... Figure 6 As shown, Figure 6 middle arrive This represents the control stress from level 1 to level 6. arrive This indicates the number of loading cycles from the first level control stress to the sixth level control stress.

[0107] The test subject used a cast steel bogie frame (i.e., bogie frame) of the same model as the failed frame, consistent with its material, structure, casting, and welding repair process. The test equipment included a bogie fatigue test bench, a four-channel vertical actuator, a dynamic strain gauge, and manual arc welding equipment. The specific installation orientation of the bogie fatigue test bench and the four-channel vertical actuator during use is as follows: Figure 4 As shown.

[0108] Dynamic strain gauges are devices that collect stress data. They are connected to strain gauges via cables, and their location is not fixed. Manual arc welding equipment is used for manual arc welding when defects are pre-existing. It is a movable device, and its location is not fixed. This allows for the implementation of a fault reproduction test method on a laboratory bench, based on actual service conditions of the railway line, TPDS wheel-rail impact monitoring data, and the principle of equivalent damage, to reproduce the entire process of crack initiation to fracture of the bogie cast steel frame.

[0109] Taking the cracking failure of the inner guide column of the side beam of the cast steel bogie of a passenger car as the object, the defect shape, size and corrosion state were first simulated. Then, the TPDS equivalent and equivalent stress relationship was established through track dynamic stress test. Combined with the turning wheel cycle maintenance data, the control stress and cycle number of each stage of the bogie were calculated according to the equal damage principle. Finally, symmetrical support, four vertical actuator loading, strain calibration of intact and defective positions, and periodic spectrum block cyclic loading were adopted until the frame cracked, thus completing the fault reproduction. The comparative analysis of this method with the existing technology is shown in Table 5.

[0110] Table 5 Comparative Analysis of Existing Technologies

[0111]

[0112] According to another embodiment of the present invention, a bogie frame fault reproduction test system based on actual service conditions is provided, comprising:

[0113] The defect pre-setting module is used to pre-set initial defects that match the actual faults in the corresponding area of ​​the bogie frame based on the location, shape, and size of the defects in the faulty frame.

[0114] The service load mapping module is used to establish the correspondence between TPDS impact equivalent and fault area equivalent stress by using TPDS impact equivalent data and line dynamic stress test data obtained by the vehicle operation quality dynamic monitoring system, and to determine the fault area equivalent stress corresponding to different TPDS impact equivalent during actual service based on the correspondence.

[0115] The damage equivalent conversion module is used to convert the equivalent stress of the fault area into the graded control stress and corresponding number of cycles in the test bench loading process by combining the actual operating mileage data of the faulty structure with the Miner linear cumulative damage criterion and the equal damage principle, forming a bench graded loading spectrum block with the turning wheel cycle as the unit.

[0116] The bench loading calibration module is used to install the pre-defected bogie frame on the test bench, constrain the bogie frame by clamping in a way that simulates the actual constraint state of the vehicle, preload according to the bench graded loading spectrum block, and determine the bench loading parameters based on the symmetrical strain calibration results of the non-destructive area and the defective area.

[0117] The fault reproduction monitoring module is used to cyclically load the bogie frame according to the bench loading parameters, monitor the crack propagation status of the preset defect area during the loading process, and obtain the fault reproduction result based on the crack propagation status.

[0118] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for reproducing bogie frame faults based on actual service conditions, characterized in that, Includes the following steps: Based on the location, shape, and size of the defects in the faulty structure, initial defects matching the actual faults are pre-set in the corresponding area of ​​the bogie frame; Based on the TPDS impact equivalent data and line dynamic stress test data obtained by the vehicle operation quality dynamic monitoring system, the correspondence between TPDS impact equivalent and fault area equivalent stress is established, and the equivalent stress of the fault area corresponding to different TPDS impact equivalents in actual service is determined based on the correspondence. Based on the actual operating mileage data of the faulty structure, combined with the Miner linear cumulative damage criterion and the equal damage principle, the equivalent stress of the faulty area is converted into graded control stress and corresponding cycle number during the loading process of the test bench, forming a bench graded loading spectrum block with the turning wheel cycle as the unit. The pre-defected bogie frame is installed on the test bench. The bogie frame is constrained by a clamping method that simulates the actual constraint state of the vehicle. Preloading is performed according to the graded loading spectrum of the bench, and the bench loading parameters are determined based on the symmetrical strain calibration results of the non-destructive region and the defective region. The bogie frame was cyclically loaded according to the bench loading parameters, and the crack propagation status of the pre-set defect area was monitored during the loading process. The fault reproduction results were obtained based on the crack propagation status.

2. The method for reproducing bogie frame faults based on actual service conditions according to claim 1, characterized in that, The initial defects that are pre-set in the corresponding area of ​​the bogie frame to match the actual faults include: Based on the location, size, and shape of the defect in the actual faulty frame, a notch corresponding to the actual fault is machined on the surface of the bogie frame. The notch was subjected to nitric acid aqueous solution corrosion treatment to simulate the corrosion state caused by long-term operating environment; The defects of incomplete fusion are formed by pre-embedding casting sand, setting tungsten rod positioning, and filling with arc welding. The defect area is then ground and repaired to make the pre-set defects consistent with the actual fault defects.

3. The bogie frame fault reproduction test method based on actual service conditions according to claim 1, characterized in that, The establishment of the correspondence between the TPDS impact equivalent and the equivalent stress in the fault area includes: Acquire dynamic strain data of the frame of the faulty wheel during operation on the faulty track; The dynamic strain data is processed by zero drift removal, strain-stress conversion, and rainflow counting to obtain the graded equivalent stress during line operation. The graded equivalent stress is fitted with the TPDS impact equivalent data at the corresponding location to obtain a linear correlation model between the TPDS impact equivalent and the equivalent stress.

4. The bogie frame fault reproduction test method based on actual service conditions according to claim 1, characterized in that, The calculation formula combining the Miner linear cumulative damage criterion and the equal damage principle is as follows: ； in, For each level of equivalent stress; This represents the number of cycles corresponding to the fatigue limit. Total structural lifespan (mileage); Control stress for each stage of the test bench; The number of cycles for the i-th level spectral block; For the first The number of kilometers corresponding to each spectral block. is the exponent of the SN curve.

5. The method for reproducing bogie frame faults based on actual service conditions according to claim 1, characterized in that, The method of constraining the bogie frame by simulating the actual constraint state of the vehicle includes: The bogie frame is mounted on top of the axle box, and the primary spring support structure of the vehicle is simulated by steel cylinders. A simulated axle is used to simulate a vehicle axle, and rigid supports are set in the wheel seat area of ​​the simulated axle to simulate the constraint state of the wheel on the bogie frame; The bogie frame is subjected to load by multiple vertical actuators acting on the bogie frame boom seats.

6. The method for reproducing bogie frame faults based on actual service conditions according to claim 1, characterized in that, The determination of the test bench loading parameters based on the symmetrical strain calibration results of the undamaged region and the defective region includes: Stress monitoring points are set in the pre-defined defect area, and corresponding stress control points and stress monitoring points are set in the non-destructive area that is symmetrical to the center of the defect area. Apply a load to the undamaged area and obtain the corresponding stress response; Adjust the load applied to the defective area until the stress response of the stress monitoring point in the defective area is consistent with the stress monitoring point in the undamaged area. The bench loading parameters are determined based on the adjusted load applied to the defect area.

7. The method for reproducing bogie frame faults based on actual service conditions according to claim 1, characterized in that, The step of cyclically loading the bogie frame according to the bench loading parameters includes: The loading spectrum is divided according to the operating mileage corresponding to the wheel turning cycle of the vehicle; According to the number of loading cycles corresponding to the graded control stress, the control stress at each level is cyclically applied; Repeatedly executing multiple loading spectrum blocks causes the steering architecture to accumulate fatigue damage corresponding to the actual operation process.

8. The method for reproducing bogie frame faults based on actual service conditions according to claim 7, characterized in that, After repeatedly executing multiple loading spectrum blocks to cause fatigue damage accumulation in the steering frame corresponding to the actual operation process, the process further includes: After each loaded spectrum block is completed, non-destructive testing is performed on the defect area; Obtain the crack length and crack propagation state in the defect area; Based on the crack length and crack propagation state, the correspondence between the number of loading cycles and the fault evolution process is recorded.

9. The method for reproducing bogie frame faults based on actual service conditions according to claim 1, characterized in that, The method of obtaining fault reproduction results based on crack propagation state includes: When the detected crack length reaches the preset crack determination size, stop the cyclic loading of the spectrum block; Based on the number of loading cycles, crack length, and crack propagation process at the time of loading cessation, the failure evolution reproduction results during the actual service process of the bogie frame are determined.

10. The method for reproducing bogie frame faults based on actual service conditions according to claim 9, characterized in that, The failure evolution reproduction results include the number of loading cycles corresponding to the crack initiation stage, the crack stable propagation stage, and the fracture failure stage.

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