A method and system for analyzing the influence of ballastless track vehicle operation stability

Abstract

This invention discloses a method and system for analyzing the impact of trackless track vehicle operation stability, belonging to the interdisciplinary technical field of railway track engineering and vehicle dynamics. First, this invention establishes a model library containing various hyperelastic constitutive models and determines the applicable strain range of each model. Then, it establishes a mapping relationship between the adjustment amount and the compressive strain of the track slab, selects the optimal constitutive model to construct a finite element model of the track slab, and obtains the nonlinear curve of the adjustment amount versus the equivalent stiffness of the track slab. Based on this curve, a three-dimensional finite element model of the trackless track structure is established and coupled with the vehicle dynamics model to form a vehicle-track coupled dynamics model. Finally, through multi-condition simulation, stability indicators such as the derailment coefficient and wheel load reduction rate are obtained, and a relationship curve between the adjustment amount and the stability indicator is established to determine the critical adjustment amount corresponding to the safety threshold. This achieves a quantitative assessment from track adjustment amount to vehicle stability indicators, significantly improving the assessment accuracy.

Description

Technical Field

[0001] This invention relates to the interdisciplinary field of railway track engineering and vehicle dynamics, and in particular to a method and system for analyzing the impact of ballastless track vehicle operation stability. Background Technology

[0002] The assessment of vehicle operational stability for ballastless track on high-speed railways is a core technical issue ensuring operational safety. Slab track consists of rails, elastic fasteners, track slabs, a cement emulsified asphalt mortar (CA mortar) adjustment layer, and a concrete base. During long-term service, the track structure is affected by factors such as foundation settlement, geological deformation, and temperature stress, requiring vertical height adjustment to restore smoothness. Height-adjustable ballastless track achieves large-scale vertical adjustment through a height adjustment system composed of fasteners, rail supports, and sleeper pads.

[0003] Currently, the main method for analyzing the operational stability of ballastless track vehicles employs a vehicle-track coupled dynamics model, which couples the vehicle system and track system through the wheel-rail contact relationship for solution. Several typical solutions exist in the existing technology: Option 1: Vehicle-rail coupling analysis based on multi-rigid-body dynamics. This method establishes the vehicle system as a multi-body dynamics model, simplifies the track system using beam or plate elements, and simulates elastic elements such as fasteners using linear spring-damped elements. The wheel-rail force is calculated using wheel-rail contact theory, and then the vehicle's dynamic response and stability indices are solved.

[0004] Option 2: Track-vehicle coupling analysis based on linear finite element method. This method discretizes each component of the track structure using three-dimensional solid elements or beam-plate elements, simplifies the fastener system to linear spring elements, establishes a finite element model of the track as a whole, and then couples it with the vehicle model for solution.

[0005] Option 3: An empirical assessment method based on track irregularity spectrum. This method obtains track irregularity data by detecting the track geometry and judges whether the stability of vehicle operation meets the requirements based on empirical formulas or standard limits.

[0006] The above-mentioned existing technical solutions have the following shortcomings: (1) The nonlinear changes caused by height adjustment are ignored. After vertical adjustment, the compression state, contact conditions and working stiffness of the elastic components under the rail of the height-adjustable ballastless track will change significantly. Rubber-type elastic pads exhibit significant hyperelastic behavior over a large strain range, and their stiffness characteristics vary greatly under different strain levels. However, existing vehicle-rail coupling models generally simplify elastic elements such as fasteners as linear springs with constant stiffness, which cannot capture the nonlinear stiffness changes of the elastic pads caused by changes in strain level after adjustment, resulting in a systematic deviation between the evaluation results and the actual working conditions.

[0007] (2) Lack of nonlinear constitutive models for materials. Track-mounted elastic pads are typically made of hyperelastic materials such as neoprene rubber, exhibiting significant nonlinear and incompressible mechanical behavior. Existing track finite element analysis lacks assessments of the applicability of various hyperelastic models across different strain ranges, and further fails to address the quantitative impact of constitutive model selection on the prediction accuracy of the dynamic response of the track-vehicle coupled system. Previous studies have shown that different hyperelastic models exhibit significantly different prediction accuracies and stability across different strain ranges.

[0008] (3) The influence of element type on analysis accuracy is neglected. In the finite element analysis of track structures, the choice of element type has a key impact on the simulation accuracy of large deformation of nonlinear materials. Studies have shown that hexahedral elements and tetrahedral elements exhibit significant differences in simulating the large deformation behavior of hyperelastic materials, and existing track finite element analysis generally lacks a systematic optimization strategy for element type.

[0009] (4) Lack of a quantitative transmission chain from adjustment amount to stability index. Existing technical solutions have failed to establish a complete quantitative transmission chain from track height adjustment amount to vehicle dynamic response, and cannot quantitatively analyze how changes in adjustment amount affect the core engineering problem of vehicle stability index. Summary of the Invention

[0010] The purpose of this invention is to provide a method and system for analyzing the impact of ballastless track vehicle operation stability, in order to solve the problem that there is a lack of quantitative evaluation methods for the operation stability of highly adjustable ballastless track after adjustment in the prior art, and in particular to overcome the deficiency of insufficient evaluation accuracy caused by neglecting the nonlinear constitutive behavior of hyperelastic materials in the existing vehicle-track coupling analysis.

[0011] In a first aspect, the present invention provides a method for analyzing the impact of ballastless track vehicle operation stability, comprising the following steps: Obtain the structural and vehicle parameters of the ballastless track; Based on the obtained parameters, a model library containing multiple hyperelastic constitutive models was established for the hyperelastic material properties of the under-rail elastic pad, and the applicable strain range of each hyperelastic constitutive model was determined. Based on the pre-established mechanical mapping relationship between the vertical height adjustment of the track and the compressive strain of the elastic pad under the track, the optimal hyperelastic constitutive model within the current strain range is selected from the model library to construct the three-dimensional solid finite element model of the elastic pad under the track, thereby establishing a nonlinear correspondence between the vertical height adjustment of the track and the equivalent stiffness of the pad under each compression state. Based on the nonlinear correspondence between the vertical height adjustment of the track and the equivalent stiffness of the pad under various compression states, a three-dimensional finite element model of the ballastless track structure, including rails, fastening system, track slab, CA mortar adjustment layer and base plate, is established. A vehicle system dynamics model is established and coupled with the three-dimensional finite element model of the ballastless track structure to form a vehicle-track coupled dynamics model; For different track vertical height adjustment conditions, the vehicle-track coupled dynamics model is used for simulation calculations to obtain vehicle operation stability evaluation indicators. Using the vertical height adjustment of the track as the independent variable and the stability evaluation index as the dependent variable, a relationship curve between the vertical height adjustment of the track and the stability index is established to determine the critical adjustment amount corresponding to when the stability index reaches the safety threshold.

[0012] Preferably, obtaining the structural parameters and vehicle parameters of the ballastless track specifically includes: Obtain the track slab dimensions and material parameters, CA mortar layer thickness and material parameters, base plate dimensions and material parameters, fastener type and arrangement spacing, elastic pad geometric dimensions and initial stiffness parameters, and height adjustment system structural parameters; Obtain vehicle type, axle load, wheelbase, suspension parameters, wheel tread profile, design operating speed range, and roughness spectrum type.

[0013] Preferably, a model library containing multiple hyperelastic constitutive models is established, and the applicable strain range of each hyperelastic constitutive model is determined, specifically including: Establish a model library including the Mooney-Rivlin model, Yeoh model, Ogden model, Arruda-Boyce model and Marlow model; Stress-strain test data of elastic pad material under different strain conditions were obtained by mechanical property tests of rubber material. The parameters of each hyperelastic model were fitted by the least squares method to obtain the material parameters of each hyperelastic constitutive model. The coefficient of determination was used to evaluate the fitting accuracy of each hyperelastic constitutive model in different strain ranges, and the Drucker stability condition was verified by the built-in stability criterion of the finite element software. The applicable strain range of each hyperelastic constitutive model was determined by a comprehensive criterion combining fitting accuracy and stability.

[0014] Preferably, the mechanical mapping relationship between the vertical height adjustment of the track and the compressive strain of the elastic pad under the track is pre-established in the following manner: The relationship between the compression increment Δh of the elastic pad under the rail and the vertical height adjustment ΔH of the rail is established using the compression transfer coefficient β. ; The compressive strain ε of the track pad is determined by the relationship between the compression increment Δh of the track pad and the initial thickness of the pad, and then the mechanical mapping relationship between the vertical height adjustment of the track and the compressive strain of the track pad is obtained.

[0015] Preferably, when the vertical height adjustment amount ΔH of the track is negative and the compression amount of the pad is reduced to zero or below, the pad and the interface of the rail bearing lose contact. At this time, the equivalent stiffness of the pad is defined by a piecewise function, and the stiffness takes a minimum value under the unloaded state.

[0016] Preferably, when constructing the three-dimensional solid finite element model of the elastic pad under the track, the element type is selected according to the geometric characteristics. Hexahedral hybrid elements are used for regular geometric regions, and tetrahedral hybrid elements are used for complex geometric regions.

[0017] Preferably, the nonlinear relationship between the vertical height adjustment of the track and the equivalent stiffness of the pad under each compression state is defined in the form of a piecewise function, wherein the stiffness value in the working zone of the pad under pressure is obtained through nonlinear static analysis, and the stiffness in the unloaded zone of the pad is taken as a minimum value.

[0018] Preferably, when establishing a three-dimensional finite element model of the ballastless track structure, the vertical height adjustment of the track is reflected at each fastener position through the change of the vertical coordinates of the track slab side nodes; the CA mortar adjustment layer uses a generalized Maxwell model to describe its viscoelastic material properties; the force-displacement nonlinear curve used for the vertical mechanical properties of the fastener system is implemented in the vehicle-track coupled dynamics solution process using a piecewise linear interpolation method, that is, each time step is dynamically interpolated based on the current relative displacement between the rail node and the track slab reference point, and the resistance value is indexed in real time.

[0019] Preferably, the vehicle operation stability evaluation index includes a derailment coefficient and a wheel load reduction rate. The derailment coefficient is the ratio of the lateral force of the wheelset to the vertical force of the wheel and rail, and the wheel load reduction rate is the ratio of the wheel load reduction amount to the static wheel weight.

[0020] Secondly, the present invention also provides a system for analyzing the impact of ballastless track vehicle operation stability, comprising: The data acquisition module is used to acquire the structural parameters and vehicle parameters of the ballastless track. The constitutive model library module is used to establish a model library containing various hyperelastic constitutive models for the hyperelastic material properties of the under-rail elastic pad based on the obtained parameters, and to determine the applicable strain range of each hyperelastic constitutive model. The nonlinear modeling module for the pad is used to select the optimal hyperelastic constitutive model within the current strain range from the model library based on the mechanical mapping relationship between the current vertical height adjustment of the track and the compressive strain of the elastic pad under the track to construct a three-dimensional solid finite element model of the elastic pad under the track, thereby establishing a nonlinear correspondence between the vertical height adjustment of the track and the equivalent stiffness of the pad under each compression state. The track structure modeling module is used to establish a three-dimensional finite element model of the ballastless track structure, including rails, fastening system, track slab, CA mortar adjustment layer and base plate, based on the nonlinear correspondence between the vertical height adjustment of the track and the equivalent stiffness of the pad under various compression states. The coupled simulation module is used to establish a vehicle system dynamic model and couple it with the three-dimensional finite element model of the ballastless track structure to form a vehicle-track coupled dynamic model. It also performs simulation calculations for different track vertical height adjustment conditions to obtain stability evaluation indicators for vehicle operation. The stability evaluation module is used to establish a relationship curve between the track vertical height adjustment amount and the stability evaluation index, with the track vertical height adjustment amount as the independent variable and the stability evaluation index as the dependent variable, so as to determine the critical adjustment amount corresponding to the stability index reaching the safety threshold.

[0021] Thirdly, embodiments of the present invention also provide an electronic device, the electronic device comprising: One or more processors; Storage device for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the method for analyzing the impact of ballastless track vehicle operation stability as described in any embodiment of the present invention.

[0022] Fourthly, embodiments of the present invention also provide a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements a method for analyzing the impact of ballastless track vehicle operation stability as described in any embodiment of the present invention.

[0023] Compared with the prior art, the present invention has the following beneficial effects: (1) The evaluation accuracy is significantly improved. By introducing the constitutive modeling technology of hyperelastic materials and the model selection strategy based on the "R²+ stability" comprehensive criterion, the systematic error caused by the simplification of the elastic pad as a linear spring in the existing methods is overcome.

[0024] (2) Establish a quantitative correspondence between regulation amount and stability. This invention provides a systematic quantitative analysis framework that can quantitatively analyze how changes in regulation amount affect the core engineering problem of vehicle stability index.

[0025] (3) Element type optimization improves computational reliability and efficiency. In finite element modeling, the element type is reasonably selected according to geometric characteristics, which effectively reduces the risk of convergence difficulties in the simulation process.

[0026] (4) This invention can be integrated into the simulation analysis platform of railway design or maintenance units to perform offline calculations for typical elevation adjustment conditions in engineering, and form an elevation adjustment-safety index comparison table or fitting formula for on-site maintenance personnel to quickly query and use. It does not require the execution of a complete simulation process each time, and has good engineering practicality. Attached Figure Description

[0027] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings. The drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a flowchart of a method for analyzing the impact of ballastless track vehicle operation stability provided by an embodiment of the present invention; Figure 2 This is a fitting curve of the constitutive model of the hyperelastic material of the elastic pad provided in the embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of a system for analyzing the impact of ballastless track vehicle operation stability provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0029] Before discussing the exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processes or methods depicted as flowcharts. Although the flowcharts describe operations (or steps) as being processed sequentially, many of these operations (or steps) may be performed in parallel, concurrently, or simultaneously. Furthermore, the order of the operations may be rearranged. The process may be terminated when its operation is completed, but may also have additional steps not included in the figures. The process may correspond to a method, function, procedure, subroutine, subroutine, etc.

[0030] Ballastless track: A track structure that replaces the traditional granular crushed stone track bed with integral materials such as concrete or asphalt mixture. Slab ballastless track consists of steel rails, elastic fasteners, track slabs, cement emulsified asphalt mortar (CA mortar) adjustment layer, concrete base and other parts.

[0031] Height-adjustable ballastless track: A ballastless track structure that can actively adjust the vertical height of the track by adjusting the fastening system, rail support platform or rail pad, etc., to adapt to engineering needs such as foundation deformation and settlement. The height adjustment system is usually composed of "fasteners + rail support platform + sleeper pad".

[0032] Vehicle-track coupled dynamics: This approach treats the vehicle system and track system as a large, interacting, and coupled system. It studies wheel-rail interaction, system dynamic response, and their impact on driving safety and stability by establishing the dynamic relationship between the two subsystems.

[0033] Hyperelastic constitutive models: constitutive models that describe the nonlinear mechanical behavior of rubber-like materials (such as elastic pads under rails) under large deformation conditions. They are based on the strain energy density function to describe the stress-strain relationship of the material. Commonly used models include the Mooney-Rivlin model, the Yeoh model, and the Ogden model.

[0034] Derailment coefficient: The ratio of lateral force to vertical force on the wheelset is one of the core indicators for evaluating vehicle operation safety, reflecting the wheels' ability to resist derailment.

[0035] Wheel load reduction rate: The ratio of wheel load reduction to static wheel weight reflects the risk of wheel derailment due to load reduction and is another core indicator for evaluating vehicle operation safety.

[0036] The core inventive concept of this invention lies in the systematic integration of nonlinear constitutive modeling technology for hyperelastic materials with vehicle-track coupled dynamics analysis. Addressing the issue of nonlinear changes in local track stiffness caused by alterations in the working state of elastic components under the track after vertical adjustment of highly adjustable ballastless tracks, this invention precisely captures the evolution of the nonlinear mechanical response of the track structure under adjustment conditions through refined finite element modeling. It establishes a quantitative transmission chain from adjustment amount to vehicle dynamics response, enabling quantitative assessment of vehicle operational stability and determination of safety thresholds. The key lies in establishing a strain-state-driven hyperelastic model selection mechanism and embedding material nonlinearity into the vehicle-track coupled dynamics solution process in real time through parametric mapping. Specifically, after accurately extracting the hyperelastic nonlinear stiffness at the material level, it is embedded into the track structure model in a downscaled manner. Then, through wheel-rail coupling, the influence of local stiffness changes is transmitted to the vehicle system-level response, ultimately forming a closed-loop quantitative chain sequentially from adjustment amount, local strain, nonlinear stiffness, track structure response, and irregularity evolution to vehicle dynamics. Within the typical parameters of high-speed railway ballastless track structure, finite element analysis shows that the equivalent stiffness of the pad plate changes significantly nonlinearly with compressive strain, with a variation range typically reaching 20% ​​to 60%. If a linear stiffness assumption is adopted, it may introduce a dynamic response deviation of about 5% to 15%. This invention effectively overcomes this defect.

[0037] Example 1 like Figure 1 The diagram shows a flowchart of a method for analyzing the impact of ballastless track vehicle operation stability according to Embodiment 1 of the present invention. The method includes the following steps: S1: Obtain the structural parameters and vehicle parameters of the ballastless track; Step S1 is used to obtain basic data. This includes obtaining the structural parameters of the ballastless track, including: track slab dimensions and material parameters, CA mortar layer thickness and material parameters, base plate dimensions and material parameters, fastener type and spacing, elastic pad geometric dimensions and initial stiffness parameters, and height adjustment system structural parameters; obtaining vehicle parameters, including vehicle type, axle load, wheelbase, suspension parameters, and wheel tread profile; and obtaining the design operating speed range and irregularity spectrum type.

[0038] In one specific embodiment, a CRTSⅠ type slab track for a high-speed railway is used as the analysis object. The track slab dimensions are 4.95m × 2.4m × 0.19m, using C60 concrete; the CA mortar layer thickness is 50mm; the base plate thickness is 300mm, using C40 concrete; the fastener spacing is 0.65m. The height adjustment system adopts a combination scheme of "fasteners + rail support platform + sleeper pad", and the total height adjustment range of the fastener system is ±30mm. The elastic pad under the rail is made of neoprene rubber, with geometric dimensions of 150mm × 80mm × 12mm, and an initial pre-compression amount... =3.6mm (corresponding to initial compressive strain) =0.30). The initial thickness of the pad is denoted as... =12mm.

[0039] The vehicle parameters adopt the CRH2 type EMU, with an axle load of 14t, an operating speed of v=350km / h, and an LMA type wheel tread profile. The irregularity excitation adopts the ballastless track spectrum of Chinese high-speed railways.

[0040] S2: Based on the obtained parameters, establish a model library containing multiple hyperelastic constitutive models for the hyperelastic material properties of the under-rail elastic pad and determine the applicable strain range of each hyperelastic constitutive model. Step S2 is used to establish a constitutive model library for elastic pad materials.

[0041] To address the hyperelastic material properties of the rubber elastic pad under the rail, a model library containing various hyperelastic constitutive models was established. The model library includes the Mooney-Rivlin model, Yeoh model, Ogden model, Arruda-Boyce model, and Marlow model.

[0042] Stress-strain test data of the elastic pad material under different strain conditions were obtained through mechanical property tests on rubber materials, such as uniaxial tensile tests, biaxial tensile tests, and plane shear tests. The least squares method was used to fit the parameters of each hyperelastic model, obtaining the material parameters of each hyperelastic constitutive model. The coefficient of determination R² was used to evaluate the fitting accuracy of each hyperelastic constitutive model within different strain ranges. Simultaneously, the Drucker stability condition was verified using the built-in stability criterion of the finite element software. The applicable strain range of each hyperelastic constitutive model was determined by a comprehensive criterion of "fitting accuracy R² + stability".

[0043] In one specific embodiment, the process of establishing a constitutive model library for elastic pad materials is as follows: The nominal stress-strain data of chloroprene rubber materials in the strain range of 0–200% were obtained through uniaxial tensile tests, equal biaxial tensile tests, and plane shear tests. The least squares method was used to fit the parameters of each hyperelastic model; all parameters are in MPa.

[0044] (1) Mooney-Rivlin model parameters: C 10 =0.351, C 01 =0.644. Where, C 10 C 01 All are material constants, in MPa, and correspond to the coefficients of the first and second strain deviator invariants, respectively.

[0045] (2) Yeoh model parameters: C10 =0.678, C 20 =0.0592, C 30 =-0.00147. Where, C 10 C 20 C 30 All are material constants, in MPa and C. 10 Dominant small strain region stiffness, C 20 To control the nonlinear response in the medium strain region (approximately 50%~150% strain), C 30 Control the gradual behavior in the large strain region (>150% strain).

[0046] (3) Ogden third-order model parameters: μ1=0.618, α1=1.30; μ2=0.00118, α2=5.00; μ3=-0.00981, α3=-2.00. Verified by the Abaqus software's stability assessment function, these parameters satisfy the Drucker stability condition within the working strain range of 0~0.75, and the strain energy function remains positive definite throughout the entire analysis strain domain. (The initial shear modulus is positive). Wherein, : Shear modulus coefficients for each order, in MPa; μ1, μ2, and μ3 are the first-order shear modulus parameter, the second-order shear modulus parameter, and the third-order shear modulus parameter, respectively. The dimensionless exponents of each order determine the rate of strain hardening or softening. α1, α2, and α3 are the first, second, and third order dimensionless exponents, respectively. Figure 2 The figure shown is the fitting curve of the constitutive model of the hyperelastic material of the elastic pad (chloroprene rubber, uniaxial tensile test data).

[0047] (4) Arruda-Boyce model parameters: μ=0.98, λ m =4.50. Where μ: initial shear modulus, in MPa, directly determines the stiffness under small strain. λ m Locked-out stretch ratio: A statistically averaged value representing the ultimate stretching limit of the molecular chain. When the strain approaches λ... m When this value is reached, the material stiffness increases sharply (lock-in effect). The larger this value is, the greater the ultimate strain that the material can withstand.

[0048] (5) The Marlow model is automatically generated by software based on the test data to generate the strain energy function.

[0049] The fitting curves of each hyperelastic model on the experimental data are as follows: Figure 2As shown in the figure, the light-shaded area indicates the working strain range of the elastic pad under the rail under typical adjustment conditions. As the strain increases, the curves of each model gradually diverge. These differences indicate that the selection of the constitutive model must match the actual working strain range; a single model cannot be simply applied to the entire strain domain. This is precisely the engineering basis for introducing the "R² + stability" comprehensive criterion for model selection in this invention. Table 1 shows the applicable strain range of each hyperelastic constitutive model.

[0050] Table 1 Applicable strain range of each hyperelastic constitutive model After filtering and preprocessing the experimental data, the fitting accuracy (R²) and stability of each model are shown in the table below. The R² values ​​above are typical experimental results; actual values ​​may vary slightly depending on the material batch. Stability is automatically determined by the built-in stability criterion of the finite element software.

[0051] In this embodiment, the compressive strain range of the pad is 0.15~0.50. The Ogden model has R²=0.990 within this range and has passed the stability verification. Therefore, the Ogden third-order model is preferred.

[0052] S3: Based on the mechanical mapping relationship between the current vertical height adjustment of the track and the compressive strain of the elastic pad under the track, select the optimal hyperelastic constitutive model within the current strain range from the model library to construct the three-dimensional solid finite element model of the elastic pad under the track, and then establish the nonlinear correspondence between the vertical height adjustment of the track and the equivalent stiffness of the pad under each compression state. S3.1: Establishment of the mapping relationship between adjustment amount and pad strain Step S3.1 is used to establish the mechanical mapping relationship between the vertical height adjustment amount ΔH of the track and the compressive strain ε of the elastic pad under the track, based on the mechanical structural characteristics of the ballastless track height adjustment system.

[0053] The mechanical mapping relationship between the track vertical height adjustment ΔH and the compressive strain ε of the elastic pad under the track is pre-established in the following way: The relationship between the compression increment Δh of the elastic pad under the track and the track vertical height adjustment ΔH is established using the compression transfer coefficient β. The compressive strain ε of the track pad is determined by the relationship between the compression increment Δh of the track pad and the initial thickness of the pad, thereby obtaining the mechanical mapping relationship between the vertical height adjustment of the track and the compressive strain of the track pad.

[0054] The definition is that ΔH>0 indicates the direction of track lifting (corresponding to the lifting of the rail bearing surface of the fastener system, and the pad being subjected to additional compression), and ΔH<0 indicates the direction of track lowering (corresponding to the lowering of the rail bearing surface of the fastener system, and the reduction of the pre-compression of the pad).

[0055] The mapping relationship between the pad compression increment Δh and the system height adjustment ΔH is established through the compression transfer coefficient β, i.e. β is defined as the proportion of the actual compression change of the pad to the total height adjustment of the system. The value of β depends on the specific mechanical topology of the height adjustment system and can be calculated based on the geometric relationship of the fastener model or determined through calibration tests. When the vertical height adjustment ΔH of the track is negative and the compression of the pad decreases to zero or below, the interface between the pad and the rail loses contact, and the system stiffness is dominated by contact nonlinearity and decreases rapidly. At this time, the piecewise stiffness function defined in step S3.2 is used for processing. That is, the equivalent stiffness of the pad adopts the value corresponding to the unloaded state in the piecewise stiffness function, that is, the stiffness takes the minimum value in the unloaded state.

[0056] In one specific embodiment, a compression transfer coefficient is defined. For a certain type of fastener system using wedge-shaped height adjustment pads, β can be determined based on the geometric relationship of the fastener's height adjustment mechanism. This fastener converts horizontal displacement into vertical displacement through the inclined surface of the wedge-shaped pads. Each rotation of the height adjustment screw generates a horizontal displacement S, which is converted into vertical displacement via the inclined surface transmission ratio η. Considering the mechanism clearance and the elastic deformation loss coefficient δ, we have β = η × (1 - δ). The loss coefficient δ ranges from 0.2 to 0.35 and can be determined through fastener height adjustment tests; correspondingly, β is typically in the range of 0.15 to 0.25. In this embodiment, β = 0.18 is selected as the typical working condition analysis value. Specifically, this coefficient β can be determined through parameter sensitivity analysis or calibration tests; this embodiment is only an exemplary value.

[0057] Initial pre-compression of the pad =3.6mm. Total compression after adjustment Compressive strain of the elastic pad under the rail .

[0058] S3.2: Refined Finite Element Modeling and Equivalent Stiffness Calculation of Hyperelastic Pads Based on the material parameters in step S2 and the compressive strain value determined in step S3.1, a three-dimensional solid finite element model of the track-mounted elastic pad is established. The elastic pad material is defined using the hyperelastic constitutive model determined in step S2, which has the highest fitting accuracy within the current strain range and satisfies the Drucker stability condition. The three-dimensional solid finite element model of the track-mounted elastic pad selects the appropriate element type based on its geometric characteristics: for example, hexahedral hybrid elements are used for regular geometric regions, and tetrahedral hybrid elements are used for complex geometric regions. Boundary conditions are set according to the actual installation constraint state of the pad.

[0059] Compressive displacement loads corresponding to each compressive strain are applied to the finite element model of the pad, and the equivalent stiffness of the pad under this compressive state (i.e., the tangential stiffness under this state) is obtained through nonlinear static analysis. Therefore, the adjustment amount ΔH and the equivalent stiffness of the pad are established. The nonlinear correspondence curve is defined using a piecewise function: in the compression working zone of the pad (compressive strain is positive), the stiffness value is determined by the equivalent stiffness of the pad obtained from nonlinear static analysis; when the pad is unloaded to the release zone (compressive strain ε ≤ 0), the stiffness takes a value close to zero (minimum value), with a range of 10. -6 ~10 -4 The value is on the order of kN / mm, selected based on numerical stability requirements. This value originates from numerical regularization under non-contact conditions and does not affect the macroscopic dynamic response results. This stiffness curve will be input into the fastener unit in step S4 as a force-displacement nonlinear curve. The equivalent stiffness of the pad... As nonlinear constitutive input parameters of the fastener unit, they directly participate in the assembly of the finite element equations of the track structure.

[0060] In one specific embodiment, a three-dimensional solid model of the pad (150mm × 80mm × 12mm) was created in Abaqus / CAE. The mesh used hexahedral hybrid elements C3D8H, with an element size of 1.5mm, totaling approximately 28,000 elements. Compressive displacement loads corresponding to different compression states were applied, and the equivalent stiffness of the pad was obtained through nonlinear static analysis. The above stiffness values ​​are obtained by fitting discrete points from finite element calculations and are used to construct piecewise nonlinear functions. In practical engineering, these values ​​can be refined based on higher resolution calculation results.

[0061] The vertical height adjustment ΔH of the track and the equivalent stiffness of the pad under various compression conditions The nonlinear correspondence between them, i.e., the stiffness curve, is defined using a piecewise function: In the compression working zone of the pad, the stiffness value is determined by the equivalent stiffness of the pad obtained from the nonlinear static analysis; in the completely unloaded state of the pad, to avoid numerical singularity problems in the finite element calculation, a minimum value (e.g., 10) is assigned to the stiffness in this degree of freedom direction. -5 This value (kN / mm) is negligible compared to the normal plate stiffness (approximately 20-40 kN / mm) and will not affect the macroscopic dynamic response. This value is a regularization technique used in numerical calculations, and those skilled in the art can adjust it according to the finite element software used and the required numerical accuracy.

[0062] Based on the above model, the equivalent stiffness of the pad under the characteristic compression state is calculated as follows: (1) ε=0.15 (low compressibility): =21.8 kN / mm; (2) ε=0.30 (initial pre-compression state): =27.6 kN / mm; (3) ε=0.50 (high compression state): =38.4 kN / mm.

[0063] The equivalent stiffness of the pad As nonlinear constitutive input parameters of the fastener unit, they directly participate in the assembly of the finite element equations of the track structure.

[0064] S4: Based on the nonlinear correspondence between the vertical height adjustment of the track and the equivalent stiffness of the pad under each compression state, a three-dimensional finite element model of the ballastless track structure including rails, fastening system, track slab, CA mortar adjustment layer and base plate is established. Step S4 is used to construct a three-dimensional finite element model of the ballastless track structure.

[0065] Specifically, a three-dimensional finite element model of the overall structure of the ballastless track is established, including the rails, fastening system, track slab, CA mortar adjustment layer, and base plate. The rails are simulated using Timoshenko beam elements or three-dimensional solid elements. In the three-dimensional finite element model, the vertical mechanical properties of the fastening system are simulated using nonlinear spring elements. These spring elements connect the rail nodes to a reference point on the track slab (hereinafter referred to as the "spring reference point"), which is located at the connection point between the track slab and the fastening system. The vertical height adjustment ΔH of the track is reflected in the model as the change in the vertical coordinate of the spring reference point at each fastener position. When ΔH>0, the track slab side node is raised by ΔH relative to its original position, and the rail responds naturally through the action of the nonlinear spring of the fastener. The track slab and base plate are simulated using three-dimensional solid elements or shell elements. The CA mortar adjustment layer is simulated using three-dimensional solid elements, and its viscoelastic material properties are described using a generalized Maxwell model. The vertical mechanical properties of the fastener system are defined using the nonlinear force-displacement curve of the pad obtained in step S3, and implemented through nonlinear spring elements. The force-displacement curve is implemented using piecewise linear interpolation. At each time step of the vehicle-track coupled dynamics solution, dynamic interpolation is performed based on the current relative displacement between the rail node and the track slab reference point, and the resistance value is indexed in real time. The lateral and longitudinal mechanical properties of the fastener are simulated using nonlinear spring-damping elements. The interlayer contact interface is simulated using a nonlinear contact model to simulate the interface bonding-slip behavior.

[0066] Track geometric irregularities are introduced into the track structure model. Based on the design irregularity spectrum type, track irregularity samples are generated using the harmonic superposition method or the trigonometric series method, and applied to the track geometric model by adding offsets to the rail node coordinates. The track model length is no less than 2 to 3 times the maximum analysis wavelength.

[0067] In one specific embodiment, a three-dimensional finite element model of the CRTSⅠ type slab track structure was established in Abaqus / Standard. The model was taken along the longitudinal direction of the track for 80m (approximately the spacing of 123 fasteners) to reflect the irregularity components with wavelengths of 1~40m. The computational scale is acceptable under conventional engineering computing resource conditions.

[0068] The rails use B31 Timoshenko beam elements with a cross-section of CHN60. The adjustment amount ΔH is reflected in the vertical coordinate offset of the spring reference point on the side of the track plate at each fastener position.

[0069] The vertical mechanical properties of the fastener system are defined by the force-displacement nonlinear curve obtained in step S3.2. The force-displacement curve is realized by piecewise linear interpolation. At each time step of the coupled dynamic solution, dynamic interpolation is performed based on the current relative displacement between the rail node and the track slab reference point, and the resistance value is indexed in real time.

[0070] The track slab uses C3D8R solid elements and a C60 concrete linear elastic model. The CA mortar adjustment layer uses C3D8R solid elements, is 50mm thick, and adopts a generalized Maxwell viscoelastic model. The viscoelastic parameters of the CA mortar can be determined according to material tests or literature recommendations; for example, the instantaneous elastic modulus is usually 7~10GPa, and the relaxation time is on the order of 0.01~1s. This embodiment selects a set of representative parameters to illustrate the effectiveness of the method: instantaneous elastic modulus E0=8.5GPa, Poisson's ratio ν=0.20; first branch relaxation modulus E1=2.1GPa, relaxation time τ1=0.05s; second branch relaxation modulus E2=1.4GPa, relaxation time τ2=0.5s.

[0071] The base plate uses C3D8R solid elements and a C40 concrete linear elastic model. The interlayer interfaces use a cohesive model with a normal stiffness K. n =1×10 6 N / mm³, tangential stiffness K t =5×10 5 N / mm³, damage initiation displacement δ0=0.1mm.

[0072] Track irregularities are generated using a trigonometric series method and applied by adding offsets to the rail node coordinates.

[0073] S5: Establish a vehicle system dynamics model and couple it with the three-dimensional finite element model of the ballastless track structure to form a vehicle-track coupled dynamics model; S5 is used to establish a vehicle-track coupled dynamics model.

[0074] Specifically, a vehicle system dynamics model is established, simplifying the vehicle into a multi-rigid-body system including the car body, bogies, wheelsets, and primary / secondary suspension. Multibody dynamics methods are used to establish the vehicle system's differential equations of motion. The vehicle system and track system are coupled through wheel-rail contact: the wheel-rail normal contact force is calculated using nonlinear Hertz contact theory or the Kik-Piotrowski non-Hertz contact model; the wheel-rail tangential creep force is calculated using Kalker linear creep theory combined with the FastSim algorithm or the Polach model.

[0075] The finite element model of the track structure established in step S4 is coupled with the dynamic model of the vehicle system through the displacement-force compatibility condition of the wheel-rail contact interface, and the coupled solution is performed using the cross-iteration method. The convergence criterion is that the relative change in wheel-rail contact force between adjacent iteration steps is less than a preset threshold, and a comprehensive judgment is made in combination with the system energy residual or displacement residual.

[0076] In one specific embodiment, during the establishment and solution of the vehicle-track coupled dynamics model: The vehicle model uses the CRH2 high-speed train with 31 degrees of freedom. The wheel-rail normal contact is based on nonlinear Hertz contact theory, and the contact stiffness... The tangential creep force was calculated using Kalker linear creep theory combined with the FastSim algorithm, and the friction coefficient was taken as 0.35.

[0077] The coupled solution employs a cross-iteration method, with the convergence criterion being that the relative change in wheel-rail contact force between adjacent iteration steps is less than 1%, combined with a comprehensive criterion based on energy residuals. Time integration utilizes the Newmark-β method, with a time step size of 1×10⁻⁶. -4 s.

[0078] S6: For different track vertical height adjustment conditions, the vehicle-track coupled dynamics model is used to perform simulation calculations to obtain the stability evaluation index of vehicle operation. Step S6 is used to perform multi-condition dynamic simulation and stability index calculation.

[0079] For different track vertical height adjustment conditions (from the minimum to the maximum design adjustment, with values ​​taken in preset steps), repeat steps S3 to S5 to obtain the vehicle-track coupled dynamic response time history curves for each condition. Calculate vehicle operational stability evaluation indicators, including: derailment coefficient. Wheel load reduction rate The calculation formula is: ; ; in For the lateral force of the wheelset, For the vertical force of the wheel and rail, The static wheel weight is used. Evaluation criteria and safety thresholds for each indicator are determined according to relevant railway specifications.

[0080] In one specific embodiment, the multi-condition dynamic simulation and stability index calculation process is as follows: Seven analysis conditions were set with ΔH ranging from -30mm to +30mm in 10mm increments. The simulation time was 0.82s (time for v=350km / h to pass through an 80m track section). The time histories of the wheel-rail vertical force Q and lateral force Y were extracted, and the derailment coefficient was calculated. Wheel load reduction rate .

[0081] The compression state of the pad under various working conditions is analyzed as follows: ΔH=-20mm: =3.6+0.18×(-20)=0mm, the pad is exactly zero compression.

[0082] ΔH=-30mm: =-1.8mm<0, the pad plate loses contact with the rail bearing interface and enters a completely unloaded state, ε is taken as 0. Take 10 -6 kN / mm. This working condition is mainly used to analyze the mechanical boundary behavior under extreme adjustment conditions. In actual engineering, a complete unloaded state is usually avoided through construction and maintenance specifications.

[0083] ΔH = +30mm: =9.0mm, theoretical strain ε=0.75. According to the rubber pad product standard (refer to HG / T 3080-2009 "Rubber Materials for Shockproof Rubber Products"), the long-term working strain of the pad should not exceed 50%. The stiffness (38.4 kN / mm) calculated under this working condition based on the upper limit of allowable strain ε=0.50 is an equivalent treatment under engineering safety constraints, used to ensure that the model is within the allowable working range of the material.

[0084] S7: Using the vertical height adjustment amount of the track as the independent variable and the stability evaluation index as the dependent variable, establish a relationship curve between the vertical height adjustment amount of the track and the stability index, so as to determine the critical adjustment amount corresponding to the stability index reaching the safety threshold.

[0085] Step S7 is used to quantify the impact on stability and determine the threshold. Using the track vertical height adjustment ΔH as the independent variable, and the maximum derailment coefficient and maximum wheel load reduction rate calculated in step S6 as dependent variables, a relationship curve between the adjustment amount and the stability index is established. Piecewise linear interpolation or nonlinear regression methods are used to determine the critical adjustment amount corresponding to each stability index reaching the safety threshold. A stability impact assessment report is then generated.

[0086] In one specific embodiment, the simulation results for the seven operating conditions are shown in Table 2: Table 2 Simulation results for 7 operating conditions Note: When ΔH = -20mm =0, ε=0; ΔH=-30mm <0, ε=0; ΔH=+30mm, taken as the upper limit of allowable strain ε=0.50.

[0087] According to the "Design Code for High-Speed ​​Railways" TB 10621-2014, the derailment coefficient limit is 0.8, and the wheel load reduction rate limit is 0.6. All operating conditions meet the requirements of the code. During positive adjustment, the stability index increases with increasing stiffness. Under the +30mm condition, the margin from the wheel load reduction rate limit is 28%, which is relatively small.

[0088] Under the parameter conditions of this embodiment, the calculated positive adjustment amount is approximately +22mm and the negative adjustment amount is approximately -20mm, which are the corresponding boundary values. These results vary with track structure parameters, pad characteristics, and vehicle conditions. The method of this invention successfully identifies the safe adjustment boundaries of the height adjustment system, providing a quantitative decision-making basis for engineering applications.

[0089] Example 2 Figure 3 This is a schematic diagram of the structure of a system for analyzing the impact of ballastless track vehicle operation stability provided in Embodiment 2 of the present invention, as shown below. Figure 3 As shown, a system for analyzing the impact of ballastless track vehicle operation stability includes: Data acquisition module 210 is used to acquire the structural parameters and vehicle parameters of ballastless track; Constitutive model library module 220 is used to establish a model library containing multiple hyperelastic constitutive models for the hyperelastic material properties of the under-rail elastic pad based on the acquired parameters, and to determine the applicable strain range of each hyperelastic constitutive model. The nonlinear modeling module 230 for the pad is used to select the optimal hyperelastic constitutive model in the current strain range from the model library according to the mechanical mapping relationship between the current vertical height adjustment of the track and the compressive strain of the elastic pad under the track to construct the three-dimensional solid finite element model of the elastic pad under the track, and then establish the nonlinear correspondence between the vertical height adjustment of the track and the equivalent stiffness of the pad under each compression state. The track structure modeling module 240 is used to establish a three-dimensional finite element model of the ballastless track structure, including rails, fastening system, track slab, CA mortar adjustment layer and base plate, based on the nonlinear correspondence between the vertical height adjustment of the track and the equivalent stiffness of the pad under each compression state. The coupled simulation module 250 is used to establish a vehicle system dynamic model and couple it with the three-dimensional finite element model of the ballastless track structure to form a vehicle-track coupled dynamic model, and to perform simulation calculations for different track vertical height adjustment conditions to obtain vehicle operation stability evaluation indicators. The stability evaluation module 260 is used to establish a relationship curve between the track vertical height adjustment amount and the stability evaluation index, with the track vertical height adjustment amount as the independent variable and the stability evaluation index as the dependent variable, so as to determine the critical adjustment amount corresponding to the stability index reaching the safety threshold.

[0090] The ballastless track vehicle operation stability impact analysis system provided in this embodiment of the invention can execute the ballastless track vehicle operation stability impact analysis method provided in any of the above embodiments of the invention. It has the corresponding functions and beneficial effects of executing the ballastless track vehicle operation stability impact analysis method. For detailed process, please refer to the relevant operations of the ballastless track vehicle operation stability impact analysis method in the foregoing embodiments.

[0091] Example 3 Figure 4 This is a schematic diagram of the structure of an electronic device provided in Embodiment 3 of the present invention. The electronic device 10 is intended to represent various forms of digital computers, and may also represent various forms of mobile devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the invention described and / or claimed herein.

[0092] like Figure 4 As shown, the electronic device 10 includes at least one processor 11 and a memory, such as a read-only memory (ROM) 12 or a random access memory (RAM) 13, communicatively connected to the at least one processor 11. The memory stores computer programs executable by the at least one processor. The processor 11 can perform various appropriate actions and processes based on the computer program stored in the ROM 12 or loaded into the RAM 13 from storage unit 18. The RAM 13 can also store various programs and data required for the operation of the electronic device 10. The processor 11, ROM 12, and RAM 13 are interconnected via a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0093] Multiple components in electronic device 10 are connected to I / O interface 15, including: input unit 16, such as keyboard, mouse, etc.; output unit 17, such as various types of displays, speakers, etc.; storage unit 18, such as disk, optical disk, etc.; and communication unit 19, such as network card, modem, wireless transceiver, etc. Communication unit 19 allows electronic device 10 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0094] Processor 11 can be a variety of general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of processor 11 include, but are not limited to, central processing unit (CPU), graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, digital signal processors (DSPs), and any suitable processor, controller, microcontroller, etc. Processor 11 performs a method for analyzing the impact of ballastless track vehicle operation stability as described above.

[0095] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and no limitation is imposed herein.

[0096] The above embodiments are merely illustrative examples and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for analyzing the impact of ballastless track vehicle operation stability, characterized in that, Includes the following steps: Obtain the structural and vehicle parameters of the ballastless track; Based on the obtained parameters, a model library containing multiple hyperelastic constitutive models was established for the hyperelastic material properties of the under-rail elastic pad, and the applicable strain range of each hyperelastic constitutive model was determined. Based on the pre-established mechanical mapping relationship between the vertical height adjustment of the track and the compressive strain of the elastic pad under the track, the optimal hyperelastic constitutive model within the current strain range is selected from the model library to construct the three-dimensional solid finite element model of the elastic pad under the track, thereby establishing a nonlinear correspondence between the vertical height adjustment of the track and the equivalent stiffness of the pad under each compression state. Based on the nonlinear correspondence between the vertical height adjustment of the track and the equivalent stiffness of the pad under various compression states, a three-dimensional finite element model of the ballastless track structure, including rails, fastening system, track slab, CA mortar adjustment layer and base plate, is established. A vehicle system dynamics model is established and coupled with the three-dimensional finite element model of the ballastless track structure to form a vehicle-track coupled dynamics model; For different track vertical height adjustment conditions, the vehicle-track coupled dynamics model is used for simulation calculations to obtain vehicle operation stability evaluation indicators. Using the vertical height adjustment of the track as the independent variable and the stability evaluation index as the dependent variable, a relationship curve between the vertical height adjustment of the track and the stability index is established to determine the critical adjustment amount corresponding to when the stability index reaches the safety threshold.

2. The method for analyzing the impact of ballastless track vehicle operation stability according to claim 1, characterized in that, The acquisition of the structural parameters and vehicle parameters of the ballastless track specifically includes: Obtain the track slab dimensions and material parameters, CA mortar layer thickness and material parameters, base plate dimensions and material parameters, fastener type and arrangement spacing, elastic pad geometric dimensions and initial stiffness parameters, and height adjustment system structural parameters; Obtain vehicle type, axle load, wheelbase, suspension parameters, wheel tread profile, design operating speed range, and roughness spectrum type.

3. The method for analyzing the impact of ballastless track vehicle operation stability according to claim 1, characterized in that, A model library containing various hyperelastic constitutive models was established, and the applicable strain range of each hyperelastic constitutive model was determined, specifically including: Establish a model library including the Mooney-Rivlin model, Yeoh model, Ogden model, Arruda-Boyce model and Marlow model; Stress-strain test data of elastic pad material under different strain conditions were obtained by mechanical property tests of rubber material. The parameters of each hyperelastic model were fitted by the least squares method to obtain the material parameters of each hyperelastic constitutive model. The coefficient of determination was used to evaluate the fitting accuracy of each hyperelastic constitutive model in different strain ranges, and the Drucker stability condition was verified by the built-in stability criterion of the finite element software. The applicable strain range of each hyperelastic constitutive model was determined by a comprehensive criterion combining fitting accuracy and stability.

4. The method for analyzing the impact of ballastless track vehicle operation stability according to claim 1, characterized in that, The mechanical mapping relationship between the vertical height adjustment of the track and the compressive strain of the elastic pad under the track is pre-established in the following manner: The relationship between the compression increment Δh of the elastic pad under the rail and the vertical height adjustment ΔH of the rail is established using the compression transfer coefficient β. ; The compressive strain ε of the track pad is determined by the relationship between the compression increment Δh of the track pad and the initial thickness of the pad, and then the mechanical mapping relationship between the vertical height adjustment of the track and the compressive strain of the track pad is obtained.

5. The method for analyzing the impact of ballastless track vehicle operation stability according to claim 4, characterized in that, When the vertical height adjustment ΔH of the track is negative and the compression of the pad decreases to zero or below, the pad loses contact with the rail interface. At this time, the equivalent stiffness of the pad is defined by a piecewise function, and the stiffness takes a minimum value under the unloaded state.

6. The method for analyzing the impact of ballastless track vehicle operation stability according to claim 1, characterized in that, When constructing the three-dimensional solid finite element model of the elastic pad under the track, the element type is selected according to the geometric characteristics. Hexahedral hybrid elements are used for regular geometric regions, and tetrahedral hybrid elements are used for complex geometric regions.

7. The method for analyzing the impact of ballastless track vehicle operation stability according to claim 6, characterized in that, The nonlinear relationship between the vertical height adjustment of the track and the equivalent stiffness of the pad under each compression state is defined in the form of a piecewise function. The stiffness value in the working zone of the pad under pressure is obtained through nonlinear static analysis, and the stiffness in the unloaded zone of the pad is taken as a minimum value.

8. The method for analyzing the impact of ballastless track vehicle operation stability according to claim 1, characterized in that, When establishing a three-dimensional finite element model of the ballastless track structure, the vertical height adjustment of the track is reflected at each fastener position through the change of the vertical coordinates of the track slab side nodes; the CA mortar adjustment layer is described by a generalized Maxwell model to describe its viscoelastic material properties; the force-displacement nonlinear curve used for the vertical mechanical properties of the fastener system is realized by piecewise linear interpolation in the vehicle-track coupled dynamics solution process, that is, dynamic interpolation is performed at each time step based on the current relative displacement between the rail node and the track slab reference point, and the resistance value is indexed in real time.

9. The method for analyzing the impact of ballastless track vehicle operation stability according to claim 1, characterized in that, The vehicle operation stability evaluation indicators include the derailment coefficient and the wheel load reduction rate. The derailment coefficient is the ratio of the lateral force of the wheelset to the vertical force of the wheel and rail, and the wheel load reduction rate is the ratio of the wheel load reduction amount to the static wheel weight.

10. A system for analyzing the impact of ballastless track vehicle operation stability, characterized in that, include: The data acquisition module is used to acquire the structural parameters and vehicle parameters of the ballastless track. The constitutive model library module is used to establish a model library containing various hyperelastic constitutive models for the hyperelastic material properties of the under-rail elastic pad based on the obtained parameters, and to determine the applicable strain range of each hyperelastic constitutive model. The nonlinear modeling module for the pad is used to select the optimal hyperelastic constitutive model within the current strain range from the model library based on the mechanical mapping relationship between the current vertical height adjustment of the track and the compressive strain of the elastic pad under the track to construct a three-dimensional solid finite element model of the elastic pad under the track, thereby establishing a nonlinear correspondence between the vertical height adjustment of the track and the equivalent stiffness of the pad under each compression state. The track structure modeling module is used to establish a three-dimensional finite element model of the ballastless track structure, including rails, fastening system, track slab, CA mortar adjustment layer and base plate, based on the nonlinear correspondence between the vertical height adjustment of the track and the equivalent stiffness of the pad under various compression states. The coupled simulation module is used to establish a vehicle system dynamic model and couple it with the three-dimensional finite element model of the ballastless track structure to form a vehicle-track coupled dynamic model. It also performs simulation calculations for different track vertical height adjustment conditions to obtain stability evaluation indicators for vehicle operation. The stability evaluation module is used to establish a relationship curve between the track vertical height adjustment amount and the stability evaluation index, with the track vertical height adjustment amount as the independent variable and the stability evaluation index as the dependent variable, so as to determine the critical adjustment amount corresponding to the stability index reaching the safety threshold.

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