A rolling contact test system for turnouts with actual wheelsets and a method for assessing turnout damage.

Abstract

This invention provides a full-scale wheelset rolling contact test system for turnouts and a method for assessing turnout damage. This method relies on a high-performance test platform that is full-scale, multi-degree-of-freedom, and can accurately reproduce the dynamic interaction between wheels and rails. The system enables the controlled introduction, dynamic monitoring, and comprehensive assessment of turnout rail damage. It solves the problems mentioned in the background technology, such as uncontrollable field tests, difficulty in replicating real-world conditions in laboratory tests, insufficient accuracy of theoretical models, and the distortion or limited degrees of freedom in existing test devices.

Description

Technical Field

[0001] This invention relates to the field of testing, and in particular to a real-size wheelset turnout rolling contact test system and a turnout damage assessment method. Background Technology

[0002] Turnouts are critical equipment on railway lines and also structurally weak points. The inherent geometric irregularities in their area induce significant wheel-rail impact loads, exacerbating wheel-rail wear and rolling contact fatigue (RCF) damage. Key components such as switch rails, stock rails, wing rails, and frog rails are subjected to complex alternating stresses (including impact loads, contact fatigue, and sliding friction), resulting in a wear rate far exceeding that of ordinary straight rails and a greater susceptibility to RCF damage. This not only directly affects the smoothness and safety of trains passing through the turnout (e.g., increasing the risk of derailment), but also significantly shortens the turnout's service life and increases maintenance costs. Therefore, effective testing and evaluation of wear and RCF damage in key components of the turnout area (especially switch rails and frogs) is a crucial foundation for improving turnout service performance.

[0003] Currently, field testing is a common method for evaluating turnout condition, but it has significant limitations: the testing cycle is long, and it is affected by factors such as the complex working conditions of the turnout laying location, the differences in the condition of operating trains, and the uncontrollable nature of on-site maintenance activities, making it difficult to systematically study the development law of fatigue damage; at the same time, the test results are easily affected by various uncontrollable factors such as the condition of the rail support, axle load, speed, laying accuracy, and vehicle condition, resulting in large data dispersion and making it difficult to provide a clear basis for the structural optimization of key components (such as frogs). Although laboratory material performance testing can be used for basic research, it is difficult to reproduce the actual stress state of multi-field coupling such as the wheel-rail stress field and temperature field on-site, and it cannot truly simulate the service environment of turnouts in operation.

[0004] This technical solution provides a real-size wheelset turnout rolling contact test system and a turnout damage assessment method to solve the above problems. Summary of the Invention

[0005] This invention addresses the challenges of existing technologies, such as long testing cycles in field trials, and the difficulty in systematically studying the development of fatigue damage due to complex working conditions at turnout installation sites, variations in operating train status, and uncontrollable on-site maintenance activities. Furthermore, test results are easily affected by uncontrollable factors like rail support conditions, axle load, speed, installation accuracy, and vehicle condition, resulting in significant data dispersion and hindering the provision of clear data for optimizing the structure of key components. While laboratory material performance testing can facilitate fundamental research, it struggles to replicate the actual stress state of multi-field coupling between wheel and rail, including stress and temperature fields, thus failing to realistically simulate the operational service environment of turnouts. This invention provides a full-scale wheelset turnout rolling contact test system, resolving these issues.

[0006] This invention provides a real-size wheelset turnout rolling contact test system, including a frame, test components, and a drive mechanism. The frame is used to provide fixed support for the test components. It adopts a hollow structure, and the test components are set inside the hollow cavity of the frame. The frame has no degree of freedom relative to the external environment. The test components include wheelset test components and turnout rail specimens. The wheelset test components simulate the wheelset structure, and the turnout rail specimens simulate the rail structure. The wheelset test assembly is a full-size wheelset structure, and it only has rotational freedom with the wheelset axle axis as the center of rotation. The turnout rail specimen includes at least one pair of rails, several fasteners, and a carrier plate. The carrier plate is a plate structure that is disassembled according to the connection relationship of the turnout rail structure. The rails are fixedly installed on the carrier plate by fasteners. The drive mechanism, fixed on the frame, is used to drive the rotation of the wheelset test assembly and the position change of the turnout rail specimen on the platform; Each wheel of the wheelset test assembly has at least one contact point with the turnout rail specimen.

[0007] The present invention provides a rolling contact test system for wheelsets of turnouts of actual size. In a preferred embodiment, the position of the wheelset test components is fixed in the translational direction relative to the frame.

[0008] This invention provides a method for assessing turnout damage during a rolling contact test of a turnout with actual wheelsets, comprising the following steps: S1. Select a real-size turnout test piece or rail section that meets the technical standards, accurately install the test piece on the test bench track platform, and secure it reliably. S2. Attach strain gauges to key parts of the specimen, calibrate other detection systems, and debug the loading and motion system; S3. Conduct static and dynamic tests; S4. Conduct online real-time monitoring and offline destructive detection and analysis; S5. Based on the results of steps S3 and S4, conduct a comprehensive performance evaluation and life prediction.

[0009] This invention provides a method for assessing turnout damage in a rolling contact test of a turnout with actual wheelsets. As a preferred method, the objects monitored in real time online specifically include load parameters, displacement parameters, motion parameters, stress response, strain response, profile evolution, and temperature field.

[0010] This invention provides a method for assessing turnout damage in a rolling contact test of a turnout with actual wheelsets. As a preferred method, other detection systems include a force-measuring wheelset, a profiler, a crack detection device, and a non-contact measurement system.

[0011] This invention provides a method for assessing turnout damage in a rolling contact test of a turnout with actual wheelsets. As a preferred method, based on the cumulative damage theory and crack propagation model, combined with measured wear rate and da / dN data, the service life of key turnout components under specific track conditions is predicted. The life prediction model is optimized by combining machine learning algorithms. The input parameters in the machine learning algorithm include axle load, speed, angle of attack, etc., and the output life prediction value and confidence interval are provided.

[0012] This invention provides a method for assessing turnout damage through a rolling contact test of actual wheelsets. As a preferred method, the static test in step S3 specifically includes: A graded loading mode was adopted, with the single-sided wheel load gradually applied to cover common axle load railway conditions. After data acquisition, the rail top elevation under 200kN wheel load was used as the benchmark, and the relative height of each characteristic section was measured using a dial indicator to establish a turnout geometric benchmark model.

[0013] This invention provides a method for assessing turnout damage through a rolling contact test of actual wheelsets. As a preferred embodiment, the dynamic test in step S3 specifically includes: Dynamic parameters are set, including total axle load, the ratio of lateral force to vertical force, platform running speed, length of constant speed section, angle of attack, number of load cycles per level, and period, and are monitored online.

[0014] The beneficial effects of this invention are as follows: This technical solution simulates the wheel-rail contact state in the turnout area using a full-scale structural model, including wheel load transfer, impact behavior, and dynamic variable cross-section contact characteristics in the switch and frog areas. It monitors the dynamic development and evolution of wear and RCF damage in real time, realistically reproducing typical damage morphologies of key components such as the switch rail and frog rail. Based on hardware, this solution provides a specialized assessment of the turnout scenario through a combination of controllable damage introduction, dynamic development monitoring, and quantitative performance evaluation. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a real-size wheelset turnout rolling contact test system; Figure 2 This is a flowchart of a method for assessing turnout damage using a real-size wheelset rolling contact test.

[0016] Figure label: 1. Frame; 2. Test components; 21. Wheelset test components; 22. Turnout rail test specimen; 3. Drive mechanism. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0018] Example 1: like Figure 1 As shown, a real-size wheelset turnout rolling contact test system includes a frame 1, a test assembly 2, and a drive mechanism 3. The frame 1 is used to provide fixed support for the test component 2. It adopts a hollow structure. The test component 2 is set inside the hollow cavity of the frame 1. The frame 1 has no degree of freedom relative to the external environment. Test component 2 includes wheelset test component 21 and turnout rail specimen 22, wherein wheelset test component 21 simulates wheelset structure and turnout rail specimen 22 simulates rail structure. The wheelset test assembly 21 is a full-size wheelset structure. The wheelset test assembly 21 only has rotational freedom with the wheelset axle axis as the center of rotation. The turnout rail specimen 22 includes at least one pair of turnout rails, several fasteners, and a carrier plate. The carrier plate is a plate structure that is disassembled according to the connection relationship of the turnout rail structure. The turnout rails are fixedly installed on the carrier plate by fasteners. In this embodiment, a working mode combining the rotation of real-scale wheelsets with the longitudinal movement of a real-scale track platform is adopted, supporting unidirectional or bidirectional reciprocating motion and directly simulating real wheel-rail rolling contact, fundamentally avoiding the fundamental distortion of "wheel-wheel" or single "wheel-rail" contact. The track platform can be equipped with real-scale finished turnouts or rail specimens, maintaining their factory condition and real structural characteristics such as variable cross-section, unevenness, and discrete support.

[0019] The drive mechanism 3 is fixed on the frame 1 and is used to drive the rotation of the wheelset test assembly 21 and the position change of the turnout rail specimen (22) on the platform.

[0020] In this embodiment, it is specifically divided into: Vertical loading unit: It adopts 8 electro-hydraulic servo actuators, with the lower 4 used to actively apply vertical load according to the axle load, and the upper 4 providing reaction force; all vertical actuators work together to apply constant preload to ensure the stability of the platform's attitude during movement and to precisely control the wheel-rail normal force.

[0021] Lateral loading unit: It is equipped with 4 lateral actuators to precisely control the lateral displacement and rotation of the platform, simulate the change of the angle of attack and curve passing behavior of the wheelset when passing through the turnout, and provide lateral constraints and longitudinal forces.

[0022] Longitudinal drive unit: The platform is driven by two longitudinal actuators to achieve longitudinal movement; the platform is supported on a low-friction sliding bearing, which significantly reduces motion resistance and enables long-term maintenance-free operation.

[0023] Each wheel of the wheelset test assembly 21 has at least one contact point with the turnout rail specimen 22.

[0024] Based on this, the driving method of this device is based on: Wheel-rail creep simulation: Simulates longitudinal creep under traction / braking conditions by controlling the wheelset drive.

[0025] The curve is simulated by using lateral, longitudinal, and vertical actuators to synchronously adjust the platform's rotation angle and spatial displacement to simulate the working conditions of the wheelset passing through a curve with a minimum radius of 300m.

[0026] This system can reproduce the three-dimensional dynamic interaction between wheels and rails, and accurately simulate complex behaviors such as wheel load transfer, impact, and variable cross-section contact in actual railway lines.

[0027] like Figure 2 As shown in this embodiment, the method for assessing turnout damage in a rolling contact test of a turnout with a corresponding physical structure is provided. Includes the following steps: S1. Select a real-size turnout test piece or rail section that meets the technical standards, accurately install the test piece on the test bench track platform, and secure it reliably. Specifically, in this embodiment, step S1 requires selecting a standard turnout test piece or rail section, approximately 3 meters in length, with an initial surface crack depth not exceeding 0.1 mm. The test piece is precisely installed on the test bench track platform with a positioning accuracy of ±0.1 mm and reliably fixed. S2. Attach strain gauges (insulation resistance ≥500MΩ) to key parts of the specimen (such as the tip of the switch rail, 50mm above the top of the core rail, etc.) to monitor dynamic stress-strain response. Fully calibrate force-measuring wheelsets (force measurement error ≤ ±0.5%), profile measuring instruments such as Miniprof with an accuracy of ±0.1mm, crack detection equipment such as penetrant, ultrasonic, eddy current or magnetic particle testing equipment, and non-contact measurement systems such as DIC digital image correlation systems; Debug the loading and motion system to ensure vertical force control accuracy of ±1% and displacement control accuracy of ±0.01mm.

[0028] S3. Conduct static and dynamic tests; In this embodiment, the static loading test adopted a graded loading mode, with single-sided wheel loads set at 150kN, 200kN, 250kN, and 300kN, covering common axle load railway conditions. The vertical loading rate was 10kN / s, and the lateral loading rate was 5kN / s, with each load level held for 60s after stabilization. Vertical force, lateral force, strain response, and displacement were collected simultaneously at a sampling frequency of 1kHz. Data was recorded every 10s, and the strain fluctuation under the same load should not exceed 2% to verify installation stability. Using the rail top elevation under a 200kN wheel load as a benchmark, a dial indicator was used to measure the relative height of each characteristic section to establish a turnout geometric benchmark model.

[0029] The dynamic loading test parameters were set as follows: the total axle load increased from 300kN to 650kN in increments of 50kN; the ratio of lateral force to vertical force was controlled between 0.2 and 0.3; the platform running speed was 5km / h; the length of the constant speed section was 900mm; the angle of attack was adjusted in 0.1mrad increments within the range of -40 to 40mrad; each load cycle was 20,000 times (approximately 14 hours); and the single cycle period was 2.5s.

[0030] Further online monitoring and intermittent testing were conducted using the following methods: real-time monitoring of various force, displacement, and strain signals; pausing the test every 5000 cycles to use a Miniprof profiler to conduct contact testing on the profile of key cross-sections and record and analyze the wear depth distribution; observing the morphology of the rail top light band and measuring its width using a portable microscope (200~500x); measuring the roughness and hardness values ​​of key cross-sections using a portable roughness measuring instrument and a Leeb hardness tester; performing an initial eddy current test (frequency 50kHz) every 10000 cycles; verifying suspected crack areas using fluorescent magnetic particle testing (UV light intensity 1000μW / cm²); using penetrant testing agent as needed; and determining crack depth using ultrasonic testing (5MHz probe).

[0031] Based on the above method, the specific termination conditions for the test are as follows: the test of that load level is terminated when the crack length of any monitored section is ≥5mm or the wear depth is ≥3mm, or the test continues by increasing the axial load if the termination condition is not triggered, until 650kN is reached or the specimen fails.

[0032] S4. Conduct online real-time monitoring and offline destructive detection and analysis; S5. Based on the results of steps S3 and S4, conduct a comprehensive performance evaluation and life prediction.

[0033] Comprehensive performance evaluation and life prediction involve linking online monitoring data, offline detection results, and microscopic analysis data into a database according to load level, cycle number, and characteristic parameters; calculating the volumetric wear and wear rate of each cross section and establishing a wear-load relationship curve; fitting the Paris formula based on crack propagation data to determine the material constants C and m; and predicting the remaining life of turnouts under different axle loads based on Miner's rule and crack propagation model.

[0034] The final output is a comprehensive evaluation report containing all test parameters, data charts, microscopic images, and life prediction results, providing a basis for turnout rail selection, structural optimization, and maintenance.

[0035] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A rolling contact test system for turnouts with actual wheelsets, characterized in that: It includes a frame (1), test components (2) and a drive mechanism (3). The frame (1) is used to provide fixed support for the test component (2). It adopts a hollow structure. The test component (2) is set inside the hollow cavity of the frame (1). The frame (1) has no degree of freedom relative to the external environment. The test assembly (2) includes a wheelset test assembly (21) and a rail test assembly (22), wherein the wheelset test assembly (21) simulates the wheelset structure, and the turnout rail specimen (22) simulates the turnout rail structure. The wheelset test assembly (21) is a full-size wheelset structure. The wheelset test assembly (21) only has rotational freedom with the wheelset axle axis as the center of rotation. The turnout rail specimen (22) includes at least one pair of turnout rails, several fasteners, and a carrier plate. The carrier plate is a plate structure that is split according to the connection relationship of the turnout rail structure. The rails are fixedly installed on the carrier plate by the fasteners. The drive mechanism (3) is fixed on the frame (1) to drive the rotation of the wheelset test assembly (21) and the position change of the turnout rail specimen (22) on the platform; Each wheel of the wheelset test assembly (21) has at least one contact point with the turnout rail specimen (22).

2. The rolling contact test system for a turnout with actual wheelsets according to claim 1, characterized in that: The position of the wheelset test assembly (21) relative to the frame (1) in the translational direction is fixed.

3. A method for assessing turnout damage during a rolling contact test of a turnout with actual wheelsets, characterized in that: Includes the following steps: S1. Select a real-size turnout test piece or rail section that meets the technical standards, accurately install the test piece on the test bench track platform, and secure it reliably. S2. Attach strain gauges to key parts of the specimen, calibrate other detection systems, and debug the loading and motion system; S3. Conduct static and dynamic tests; S4. Conduct online real-time monitoring and offline destructive detection and analysis; S5. Based on the results of steps S3 and S4, conduct a comprehensive performance evaluation and life prediction.

4. The method for assessing turnout damage in a rolling contact test of a turnout with actual wheelsets according to claim 3, characterized in that: The objects monitored in real time online specifically include load parameters, displacement parameters, motion parameters, stress response, strain response, profile evolution, and temperature field.

5. The method for assessing turnout damage in a rolling contact test of a turnout with actual wheelsets according to claim 3, characterized in that: The other detection systems include force-measuring wheelsets, profilers, crack detection equipment, and non-contact measurement systems.

6. The method for assessing turnout damage in a rolling contact test of a turnout with actual wheelsets according to claim 3, characterized in that: The specific method for lifetime prediction in step S5 is as follows: Based on the cumulative damage theory and crack propagation model, combined with measured wear rate and da / dN data, the service life of key turnout components under specific track conditions is predicted. The service life prediction model is optimized by combining machine learning algorithms. The input parameters of the machine learning algorithm include axle load, speed, angle of attack, etc., and the output is the predicted service life value and confidence interval.

7. The method for assessing turnout damage in a rolling contact test of a turnout with actual wheelsets according to claim 3, characterized in that: The static test described in step S3 specifically includes: A graded loading mode was adopted, with the single-sided wheel load gradually applied to cover common axle load railway conditions. After data acquisition, the rail top elevation under 200kN wheel load was used as the benchmark, and the relative height of each characteristic section was measured using a dial indicator to establish a turnout geometric benchmark model.

8. The method for assessing turnout damage in a rolling contact test of a turnout with actual wheelsets according to claim 3, characterized in that: The dynamic test described in step S3 specifically includes: Dynamic parameters are set, including total axle load, the ratio of lateral force to vertical force, platform operating speed, length of constant speed section, angle of attack, number of load cycles per level, and period, and are monitored online.

Images