Method for calculating equivalent stress of wheel-rail large impact interference

Abstract

A method for calculating equivalent stress of excluding wheel rail large impact interference, relates to the field of high-speed motor train unit bogie system, solves the problems that the existing equivalent stress calculation method cannot guide line maintenance, and the test data of the actual line includes the test signal of wheel rail large impact interference and cannot be eliminated, and the like, the method can predict the equivalent stress of the bogie frame after excluding the wheel rail large impact according to the actually measured wheel rail large impact signal, and can effectively guide the establishment of line maintenance standard. The method can calculate the equivalent stress amplitude of the bogie frame without large impact by excluding the wheel rail large impact interference, evaluate the line maintenance state, and predict the actual equivalent stress of the bogie frame under the condition without large impact. The reasonable line maintenance standard is established, so that the structure strength of the bogie frame meets the requirements in the use process, and damage does not occur.

Description

Technical Field

[0001] This invention relates to the field of high-speed train bogie systems, and specifically to a method for calculating equivalent stress of a frame to eliminate wheel-rail impact interference. Background Technology

[0002] With the rapid development of the rail transit industry, higher requirements have been placed on rail transit equipment. As the most important component affecting the safety of rail vehicles, the safety of the running gear is particularly crucial. The bogie frame, as the bridge supporting and connecting other components of the running gear, has always been an important topic in the rail transit industry for lifespan assessment.

[0003] Currently, before a rail vehicle bogie is put into service, various methods such as simulation analysis, bench testing, and track testing are used to assess the structural strength of the newly designed bogie to ensure that the bogie meets the structural strength requirements during use, preventing damage that could affect driving safety and cause loss of life and property.

[0004] In track testing, the equivalent stress assessment method is a widely adopted and reasonable approach in the rail transit industry. Although bogie frames must meet rigorous review processes and stringent testing conditions before being put into use, various factors can still lead to cracks or insufficient lifespan during actual use, resulting in excessive equivalent stress indicators. Wheel-rail impact is the most significant cause of excessive equivalent stress. To extend the frame's service life, track modifications are sometimes unavoidable. This necessitates analyzing measured data to evaluate track modification standards. However, actual track test data includes test signals affected by large wheel-rail impacts, thus necessitating a method to assess the equivalent stress of the frame under conditions without large wheel-rail impacts.

[0005] Currently, conventional equivalent stress calculations are widely used for measured lines, but there are no methods for calculating equivalent stress in areas where interference in measured data is eliminated. For example... Figure 1 As shown, the traditional equivalent stress evaluation method mainly relies on measured stress data. After filtering to eliminate electrical system interference and trend filtering, rainflow counting is performed. The rainflow counting results are then classified to facilitate computer calculation, and the equivalent stress is calculated based on the actual SN curve of the material.

[0006] Traditional equivalent stress calculation methods can calculate the equivalent stress of the structure under actual track conditions. However, the equivalent stress under actual track conditions cannot guide track maintenance. It is necessary to find a method to calculate the equivalent stress of the structure under different standard track conditions. A method that excludes wheel-rail large impact interference in calculating the equivalent stress of the structure can meet the requirements. Summary of the Invention

[0007] To address the problems that existing equivalent stress calculation methods cannot guide track maintenance, and that actual track test data includes test signals of large wheel-rail impact interference that cannot be eliminated, this invention provides a method for calculating equivalent stress by excluding large wheel-rail impact interference.

[0008] A method for excluding the equivalent stress of a calculation framework from large wheel-rail impact interference, the method is implemented by the following steps:

[0009] Step 1: Collect measured data, calculate the kurtosis value of the measured signal, and analyze whether there is a large impact signal in the signal;

[0010] Step 2: Count the major impact points and determine whether the number and magnitude of the impact points meet the requirements. If yes, proceed to Step 4; otherwise, proceed to Step 3.

[0011] Step 3: Based on the axle box vibration acceleration and vehicle speed, perform a time-delay correlation analysis with the frame stress to verify the impact point location. Then, eliminate the impact point locations for each cycle until the requirements are met, and proceed to Step 4.

[0012] Step 4: Calculate the equivalent stress of the time-domain signal after stress elimination, compare the equivalent stress before and after elimination, and output a report using the lifetime and kurtosis indices.

[0013] The beneficial effects of this invention are:

[0014] This invention can predict the equivalent stress of the structure after eliminating large wheel-rail impacts based on measured large wheel-rail impact signals. It can effectively guide the formulation of track maintenance standards.

[0015] By excluding large wheel-rail impact interference, the equivalent stress amplitude of the bogie frame without large impact is calculated to assess the track condition and predict the actual equivalent stress of the frame under conditions without large impact. Reasonable track maintenance standards are then established to ensure that the bogie frame meets structural strength requirements and does not suffer damage during use. Attached Figure Description

[0016] Figure 1 A flowchart of existing equivalent stress calculation methods;

[0017] Figure 2 This is a flowchart of a method for calculating equivalent stress of a framework to eliminate large wheel-rail impact interference, as described in this invention. Detailed Implementation

[0018] Combination Figure 2 This embodiment describes a method for eliminating the equivalent stress of a calculation framework affected by large wheel-rail impacts. This method is implemented through the following steps:

[0019] Step 1: Obtain actual track data through sensors and data acquisition system. The actual track data includes vehicle speed, frame stress and axle box vibration acceleration data.

[0020] Step 2: Based on the obtained frame stress data, calculate the proportion of large impact in the stress data and axle box vibration acceleration data, and determine whether the large impact meets the requirements. If the large impact meets the requirements, then proceed to step 5; otherwise, proceed to step 3.

[0021] In this embodiment, it is required that the amplitude of the impact acceleration of the axle box vibration is not greater than 70g, and the time occupied by the impact with the axle box acceleration amplitude less than 70g is less than the measurement time under the non-zero velocity state of 0.03% (the impact time is calculated by taking the envelope spectrum, taking the amplitude of the 0.03% quantile point before strain as the start and end amplitude, and the time interval between the start and end times of the envelope spectrum).

[0022] Step 3: Based on the axle box vibration acceleration and frame strain, calculate the delay time through time delay correlation analysis, and then determine the specific time and location of the strain impact point in the test data based on the vehicle speed, and proceed to Step 4.

[0023] Step 4: Extract the impact point location from Step 3, remove the data from the velocity, strain, and vibration acceleration signals, and return to Step 2;

[0024] Step 5: Calculate the equivalent stress. The calculation method is the same as the traditional equivalent stress calculation method, but the influence of the wheel-rail impact has been eliminated in the signal.

[0025] Step 6: Compare the equivalent stress calculation results and service life before and after eliminating the wheel-rail impact, and simultaneously calculate the strain signal kurtosis before and after eliminating the wheel-rail impact as an auxiliary verification, and output the calculation report.

[0026] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0027] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for calculating equivalent stress of a framework to eliminate interference from large wheel-rail impacts, characterized by: This method is implemented by the following steps: Step 1: Collect measured data, calculate the kurtosis value of the measured signal, and analyze whether there is a large impact signal in the signal; Step 2: Count the major impact points and determine whether the number and magnitude of the impact points meet the requirements. If yes, proceed to Step 4; otherwise, proceed to Step 3. Step 3: Based on the axle box vibration acceleration and vehicle speed, perform a time-delay correlation analysis with the frame stress to verify the impact point location. Then, eliminate the impact point locations for each cycle until the requirements are met, and proceed to Step 4. Step 4: Calculate the equivalent stress of the time-domain stress signal after stress elimination, compare the equivalent stress before and after elimination, and output a report using the lifetime and kurtosis indices.

2. The method for calculating equivalent stress of a wheel-rail large impact interference calculation framework according to claim 1, characterized in that: In step one, the collected measured data includes the acquisition of measured data on vehicle speed, axle box vibration, and frame stress using sensors, accelerometers, and strain gauges, respectively.

3. The method for calculating equivalent stress of a wheel-rail large impact interference calculation framework according to claim 1, characterized in that: In step two, the stress data of the frame and the vibration acceleration data of the axle box are calculated to determine the proportion of large impacts. It is determined whether the large impacts meet the requirements. The axle box vibration acceleration impact acceleration amplitude is required to be less than or equal to 70g, and the time occupied by impacts with axle box acceleration amplitude less than 70g is less than 0.03% of the velocity measurement time under non-zero conditions.

4. The method for calculating equivalent stress of a wheel-rail large impact interference calculation framework according to claim 1, characterized in that: The specific process of step three is as follows: Based on the axle box vibration acceleration and frame stress, the delay time is calculated through time delay correlation analysis. Then, based on the vehicle speed, the time of the strain impact point and its location in the test data are determined. For all impact points within a cycle, the data at that point is eliminated from the velocity, strain, and vibration acceleration signals.

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