Interface damage analysis method and device for ballastless track under coupling of high-low cyclic loading

Abstract

The application discloses a kind of high-low cycle cyclic load coupling under ballastless track interface damage analysis method and device, comprising: input track interface attribute, determine current stress and displacement, and mixed mode and failure displacement;Judge whether track interface is damaged;If interface has not been damaged, then update static damage variable under the action of sustained monotonic load or fatigue damage variable under the action of cyclic load;If track interface is damaged, judge whether cyclic load is applied;The cyclic load at least includes high cycle cyclic load and low cycle cyclic load;If cyclic load is not applied, update static damage variable under the action of monotonic load;If cyclic load is applied, update fatigue damage variable under the action of cyclic load, interface total damage variable;Determine the threshold when different cyclic load produces damage to interface, and the threshold when interface completely fails.The application can realize high-low cycle cyclic load coupling under ballastless track interface cumulative fatigue analysis.

Description

Technical Field

[0001] This invention belongs to the field of rail transit technology, specifically a method and apparatus for analyzing interface damage of ballastless track under high and low cycle cyclic load coupling. Background Technology

[0002] Ballastless track structures are the main track structure form for high-speed and ordinary railways in my country. These track structures are mainly composed of vertical multi-layered concrete structures such as rails, fasteners, sleepers, track slabs, mortar buffer layers, and base plates. The track slabs are precast and made of C55 concrete, while the mortar buffer layers may be cast-in-place using emulsified asphalt mortar. The base plates are cast-in-place C40 concrete foundations. Therefore, the interlayer bonding performance of the track slabs, mortar buffer layers, and base plates is the weak link in ballastless track structures.

[0003] The design life of ballastless track structures is generally 60 years. During their service life, ballastless track structures face complex train loads and temperature effects. Current research on the impact of various environmental factors on the interfacial bonding performance of ballastless track mainly analyzes the effects of individual high-cycle train loads or individual low-cycle temperature loads, often neglecting the coupled effects of high-cycle and low-cycle cyclic loads. Due to the significant differences in characteristics between high-cycle and low-cycle cyclic loads, the interfacial bonding performance of the track slab, mortar buffer layer, and base plate is more susceptible to fatigue damage under the coupled effects of these loads, leading to defects such as interlayer separation and voids.

[0004] Therefore, there is an urgent need to design a method for analyzing the cumulative fatigue damage of the ballastless track interface under the coupled action of high and low cycle cyclic loads. Summary of the Invention

[0005] The purpose of this invention is to provide a method and apparatus for analyzing interface damage of ballastless track under high- and low-cycle cyclic load coupling, so as to solve the technical problem in the prior art that the coupling effect of high-cycle cyclic load and low-cycle cyclic load is not analyzed when studying the influence of various factors in the service environment on the interface bonding performance of ballastless track.

[0006] Therefore, this invention provides a method for analyzing interface damage of ballastless track under coupled high and low cycle loads, including:

[0007] Input track interface properties to determine the current stress and displacement, as well as the hybrid mode and failure displacement;

[0008] Based on the current stress and displacement, mixed mode and failure displacement, determine whether the ballastless track interface is damaged; if the interface is not yet damaged, update the static damage variable under continuous monotonic load or the fatigue damage variable under cyclic load; if the track interface is damaged, determine whether to apply cyclic load; the cyclic load includes at least one high-cycle cyclic load and one low-cycle cyclic load.

[0009] If no cyclic load is applied, update the static damage variable under monotonic load; if cyclic load is applied, update the fatigue damage variable under cyclic load; calculate the total interface damage variable based on the fatigue damage variable and the static damage variable.

[0010] Based on the static damage variables under monotonic load, the fatigue damage variables under cyclic load, and the total interface damage variables, the thresholds at which different cyclic loads begin to cause damage to the interface and the thresholds at which the interface completely fails are determined.

[0011] This invention studies fatigue damage variables under individual high-cycle cyclic loading, individual low-cycle cyclic loading, and coupled high- and low-cycle cyclic loading. By comparing these fatigue damage variables under cyclic loading with static damage variables under monotonic loading and total interface damage variables, it is possible to determine the threshold at which different cyclic loads begin to cause damage to the interface and the threshold at which the interface completely fails. This allows for the analysis of the evolution process of interfacial bonding performance and the evolution law of cumulative interface fatigue damage under different high- and low-cycle cyclic loading.

[0012] In a preferred embodiment of the present invention, the updated fatigue damage variables under cyclic loading include:

[0013] Input a pre-constructed nonlinear fatigue cohesion model;

[0014] The nonlinear fatigue cohesion model is imported into the pre-constructed three-dimensional thermo-mechanical coupling model;

[0015] Calculate the fatigue damage variables under cyclic loading.

[0016] In a more preferred embodiment of the present invention, the method for constructing the nonlinear fatigue cohesive model includes: deriving the formula for the nonlinear fatigue cohesive model of the ballastless track interface based on the fatigue cohesive model of the composite structure.

[0017] In a more preferred embodiment of the present invention, the method for constructing the three-dimensional thermo-coupling model includes:

[0018] Establish ballastless track solid units;

[0019] Nonlinear fatigue cohesive force model parameters are selected between the vertical multi-layers of the ballastless track and between the longitudinal plates of the ballastless track;

[0020] Three-dimensional thermo-mechanical coupling models of ballastless track were established using finite element analysis software. The three-dimensional thermo-mechanical coupling models include heat conduction under low-cycle load and thermo-mechanical coupling models under dynamic action of high-cycle load.

[0021] The thermodynamic response of the ballastless track under cyclic load coupling was calculated, and the results were compared with those from pre-set experiments or literature to verify and correct the three-dimensional thermodynamic coupling model.

[0022] In a more preferred embodiment of the present invention, the calculation of fatigue damage variables under cyclic loading includes: calculating fatigue damage variables under each type of cyclic loading, and the total fatigue damage variable under all coupled cyclic loading.

[0023] In a more preferred embodiment of the present invention, the fatigue damage variables include: temperature field and stress field at the ballastless track interface, relative displacement, axial force at both ends, stiffness reduction, and damage factor.

[0024] In a more preferred embodiment of the present invention, the total interface damage variable is the sum of the fatigue damage variable and the static damage variable, or the larger value between the fatigue damage variable and the static damage variable.

[0025] In a more preferred embodiment of the invention, the cyclic load includes at least a temperature cyclic load and a train cyclic load.

[0026] Another aspect of the present invention provides a device for analyzing fatigue damage at a track interface under cyclic load coupling, comprising:

[0027] The input module is used to input track interface properties, determine the current stress and displacement, as well as the hybrid mode and failure displacement;

[0028] The judgment module is used to determine whether the ballastless track interface is damaged based on the current stress and displacement, mixed mode and failure displacement; and to determine whether to apply cyclic load.

[0029] The calculation module is used to calculate fatigue damage variables under cyclic loading, static damage variables under monotonic loading, and total interface damage variables.

[0030] The analysis module is used to determine the threshold at which different cyclic loads begin to cause damage to the interface and the threshold at which the interface completely fails, based on the static damage variables under monotonic loads, the fatigue damage variables under cyclic loads, and the total interface damage variables.

[0031] Another aspect of the present invention provides a terminal, including a memory and a processor, wherein the memory stores a computer-readable program that can be executed by the processor; when the processor executes the computer-readable program, it implements the method for analyzing the interface damage of ballastless track under high and low cycle cyclic load coupling as described above.

[0032] Compared with the prior art, the features and beneficial effects of the present invention are as follows: The present invention studies the fatigue damage variables under individual high-cycle cyclic loading, individual low-cycle cyclic loading, and the coupled action of high and low-cycle cyclic loading. By comparing the fatigue damage variables under these cyclic loading actions with the static damage variables under monotonic loading and the total interface damage variables, it is possible to determine the threshold at which different cyclic loadings begin to cause damage to the interface and the threshold at which the interface completely fails. This allows for the analysis of the evolution process of interface bonding performance and the evolution law of interface fatigue cumulative damage under different high and low-cycle cyclic loading. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0034] Figure 1 This is a flowchart illustrating the interface damage analysis method for ballastless track under high and low cycle cyclic load coupling according to the present invention.

[0035] Figure 2 This is a schematic diagram of the vertical multi-layered ballastless track of the present invention.

[0036] Figure 3 The diagram shows the bilinear and nonlinear cohesive force models for interface fatigue of the present invention; (a) is the bilinear cohesive force model; (b) is the nonlinear cohesive force model.

[0037] Figure 4 This is a flowchart illustrating the application of a fatigue cohesive force model in one implementation of the present invention.

[0038] Figure 5 This is a schematic diagram of the cyclic temperature and high and low cycle loads of the train load according to the present invention.

[0039] Figure 6 This is a schematic diagram of the ballastless track structure of the present invention, including train load and temperature.

[0040] Figure 7This is a schematic diagram of the fatigue damage evolution of the ballastless track interface under temperature and train load according to the present invention; (a) shows the load and temperature at 0.25 hours; (b) shows the load and temperature at 18 hours.

[0041] Figure 8 This invention relates to the displacement changes of the interlayer interface of ballastless track under temperature and train load.

[0042] Figure 9 This is a schematic diagram of the ballastless track interface damage analysis device under high and low cycle cyclic load coupling according to the present invention.

[0043] Figure 10 This is a functional schematic diagram of the terminal of the present invention. Detailed Implementation

[0044] This invention provides a method and apparatus for interface damage analysis of ballastless track under coupled high and low cycle loads. To make the objectives, technical solutions, and effects of this application clearer and more explicit, the following detailed description is provided with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining this application and are not intended to limit this application.

[0045] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this application’s specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when the invention refers to an element as being “connected” or “coupled” to another element, it may be directly connected or coupled to the other element, or there may be intermediate elements. Furthermore, “connected” or “coupled” as used herein may include wireless connections or wireless coupling. The term “and / or” as used herein includes all or any units and all combinations of one or more associated listed items.

[0046] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0047] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0048] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0049] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0050] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0051] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0052] Exemplary methods

[0053] During service, ballastless track structures face complex environmental factors, especially high-cycle cyclic loads (such as train cyclic loads) and low-cycle cyclic loads (such as temperature cyclic loads). Temperature cyclic loads are the longest-lasting low-cycle cyclic loads that ballast tracks bear during service, while train cyclic loads are one of the most significant cyclic loads on longitudinally connected ballastless tracks. The load characteristics of temperature cyclic loads and train cyclic loads differ greatly. Under the coupled action of these two cyclic loads, the interlayer bonding performance of the track slab, mortar buffer layer, and base plate is more prone to fatigue damage, leading to track defects such as interlayer separation and voids.

[0054] Based on this, the present invention provides a method for interface damage analysis of ballastless track under coupled high and low cycle loads, such as... Figure 1 As shown, the method for analyzing interface damage of ballastless track under coupled high and low cycle loads includes:

[0055] S100, Input track interface properties to determine current stress and displacement, as well as hybrid mode and failure displacement;

[0056] S200. Based on the current stress and displacement, mixed mode and failure displacement, determine whether the ballastless track interface is damaged; if the interface is not yet damaged, update the static damage variable under continuous monotonic load or the fatigue damage variable under cyclic load; if the track interface is damaged, determine whether to apply cyclic load.

[0057] S300: If no cyclic load is applied, update the static damage variable under monotonic load; if a cyclic load is applied, update the fatigue damage variable under cyclic load; calculate the total interface damage variable based on the fatigue damage variable and the static damage variable.

[0058] S400. Based on the static damage variable under monotonic load, the fatigue damage variable under cyclic load, and the total interface damage variable, determine the threshold when different cyclic loads begin to cause damage to the interface and the threshold when the interface completely fails.

[0059] In this embodiment, the method for analyzing the interface damage of ballastless track under high and low cycle cyclic load coupling is mainly used to analyze the track interface damage in the ballastless track structure. The ballastless track structure can be a vibration-damping ballastless track, a CRTSⅠ type slab ballastless track, a CRTSⅡ type slab ballastless track, a CRTSⅢ type slab ballastless track, a CRTSⅡ type double-block ballastless track, a CRTSⅠ type double-block ballastless track, a floating slab track structure, etc.

[0060] like Figure 2 As shown, in one implementation of this embodiment, the ballastless track structure is mainly composed of a vertical multi-layered concrete structure including rails, fasteners, sleepers, track slabs, mortar buffer layer, and base plate, wherein the interface bonding performance between the track slab, mortar layer, and base plate is [not specified].

[0061] Specifically, the method for analyzing the interface damage of ballastless track under coupled high and low cycle loads is implemented through fatigue cohesion model analysis. The fatigue cohesion model is a nonlinear fatigue cohesion model improved from a bilinear cohesion model, such as... Figure 3 As shown, by Figure 3 The bilinear cohesion model shown in (a) is changed to Figure 3 The nonlinear cohesive force model shown in (b) is used. Of course, in other implementations of this embodiment, the nonlinear fatigue cohesive force model can be transformed into a nonlinear fatigue cumulative damage model improved from multilinear, exponential, trapezoidal, etc.

[0062] This embodiment, through the aforementioned nonlinear fatigue cohesive model, can fully consider the cumulative fatigue damage under cyclic loading. Based on this, a three-dimensional thermo-mechanical coupling model of slab track under the coupled action of temperature and train load is established. The model compares and analyzes the temperature conduction, interface stress field, and displacement of the ballastless track interface under different individual temperature amplitudes, speeds, and cycle times, different individual train speeds, axle loads, and number of cycles, as well as the damage factor under the combined action of these two loads. This enables the cumulative fatigue analysis of the ballastless track interface under high and low cycle cyclic loading.

[0063] In step S100, track interface properties need to be input into the analysis software to determine the current stress and displacement of the ballastless track interface, as well as the hybrid mode and failure displacement; wherein, the hybrid mode can be a bilinear cohesive model of interface damage in multiple directions, such as a hybrid model of tangential and normal damage.

[0064] In step S200, it is necessary to determine whether the ballastless track interface is damaged based on the current stress and displacement, mixed mode and failure displacement of the ballastless track interface; if the interface is not yet damaged, the static damage variable under continuous monotonic load or the fatigue damage variable under cyclic load is updated; since there is also cyclic load before the ballastless track interface is damaged, the static damage variable and the total interface damage variable are updated when the interface is not yet damaged.

[0065] If the track interface is damaged, it is determined whether to apply a cyclic load; the cyclic load described in this embodiment includes at least one high-cycle cyclic load and one low-cycle cyclic load; such as Figure 5 As shown, Figure 5 For cyclic temperature and high and low cycle loads of train load, such as Figure 6 As shown, Figure 6 A scenario for applying train loads and temperatures to a ballastless track structure.

[0066] For example, the cyclic load includes at least temperature cyclic load and train cyclic load. It is understood that the cyclic load of the present invention may also include other cyclic loads besides temperature cyclic load and train cyclic load, such as wind load, rain load, etc. Other cyclic loads may be high-cycle cyclic loads or low-cycle cyclic loads.

[0067] Of course, in this embodiment, when selecting the cyclic load, the size, rate and cycle time of the selected temperature cyclic load can be changed, and the size, frequency and number of cycles of the selected train cyclic load can also be changed.

[0068] When determining whether to apply cyclic loading, if no cyclic loading is applied, the static damage variable under monotonic loading is updated; if cyclic loading is applied, the fatigue damage variable under cyclic loading is updated. Furthermore, the total interface damage variable is calculated based on the fatigue damage variable and the static damage variable. The fatigue damage variable includes: the temperature and stress fields of the ballastless track interface, relative displacement, axial forces at both ends, stiffness reduction, and damage factor. The total interface damage variable is the sum of the fatigue damage variable and the static damage variable, or the larger value between the fatigue damage variable and the static damage variable.

[0069] In one implementation of this embodiment, the method for updating the fatigue damage variable under cyclic loading in step S300 includes:

[0070] S310, Input the pre-built nonlinear fatigue cohesion model.

[0071] In this embodiment, during the process of updating the fatigue damage variables under cyclic loading, a pre-constructed nonlinear fatigue cohesion model needs to be input into the analysis software; wherein, the method for constructing the nonlinear fatigue cohesion model includes:

[0072] S311. Based on the fatigue cohesive force model of the composite structure, derive the formula for the nonlinear fatigue cohesive force model of the ballastless track interface.

[0073] In this embodiment, the nonlinear fatigue cohesion model can define unloading-reloading path rules for temperature and train cyclic loads. The loading path in the unloading-reloading path rules is determined based on the temperature rise amplitude, rate, and time of the cyclic temperature load, or based on the vehicle wheel weight, speed, and time when the cyclic train load passes. The unloading path in the unloading-reloading path rules is determined based on the temperature drop amplitude, rate, and time. It can be determined that the unloading in this embodiment is the process after the cyclic train load passes (loads).

[0074] After defining the unloading-reloading path rules for train cyclic loads, the fatigue damage variables of the track interlayer interface under cyclic loads can be derived. These fatigue damage variables can be derived based on their damage factors, which are defined as follows:

[0075] Where E0 is the elastic modulus of concrete.

[0076] After deriving the fatigue damage variable, it is introduced into the static damage variable of the bilinear cohesive model under monotonic loading. Simultaneously, the static and fatigue cohesive constitutive relations under monotonic and cyclic loading are considered, and the relationship between monotonic damage, fatigue damage, and total damage is reasonably defined. The static and fatigue cohesive constitutive relations include seven cases: static cohesive constitutive relations under monotonic temperature load, static cohesive constitutive relations under monotonic train load, fatigue cohesive constitutive relations under cyclic temperature load, fatigue cohesive constitutive relations under cyclic train load, fatigue cohesive constitutive relations under the coupled action of monotonic temperature load and cyclic train load, fatigue cohesive constitutive relations under the coupled action of monotonic train load and cyclic temperature load, and fatigue cohesive constitutive relations under the coupled action of cyclic temperature load and cyclic train load.

[0077] Specifically, the nonlinear fatigue cohesive force model of the ballastless track interface in this invention includes a thermo-mechanical coupling model under the thermal conduction of low-cycle load and the dynamic action of high-cycle load.

[0078] 1) Low-period nonlinear fatigue cohesion model

[0079] When the number of cycles is less than 104, the damage process is usually regarded as low-cycle fatigue damage behavior; the typical interface fatigue damage constitutive model can adopt the irreversible damage model proposed by scholars Roe and Siegmund.

[0080] Damage change rate under monotonic load It can be characterized as: In the formula, the subscripts t and t-Δt represent the current time step and the previous time step, respectively, and the symbols are... This represents the composite displacement value of the interface in composite mode. This represents the initial normal opening displacement.

[0081] Damage change rate under low-cycle cyclic loading It can be characterized as:

[0082] In the formula, H(x) is the Heavisidec function, used to control the displacement opening threshold; the additional parameter σ is introduced. f δΣ represents the damage tolerance; δΣ represents the cumulative cohesive length, and δΣ represents the normalized increment of the equivalent displacement. Its value determines the cumulative equivalent displacement value required for interface cracking when the cohesive region fails, and its magnitude is an integer multiple of the damage initiation displacement. The current stress value, i.e., the current traction force in the cohesive force model, σ max This represents the maximum traction force value under the current damage condition.

[0083] The interface damage under low-cycle loading consists of static damage and fatigue damage, and the total damage variable D can be characterized as: or

[0084] 2) High-period nonlinear fatigue cohesion model

[0085] The interface damage under high-cycle loading consists of static damage and fatigue damage; therefore, the high-cycle fatigue damage rate of the interface can be expressed as:

[0086]

[0087] The rate of change of damage under monotonic load is:

[0088]

[0089] Based on the continuous damage model proposed by Peerlings for high-cycle fatigue damage at interfaces, the rate of change of fatigue damage can be expressed as:

[0090]

[0091] In the formula, C represents the fatigue damage coefficient, β represents the fatigue damage index, λ is the fatigue damage amplification coefficient, and Gth is the energy release rate threshold used to determine the initiation of fatigue damage. The parameters C and β need to be determined experimentally, while λ is selected based on the dependence of the current damage state on the damage rate.

[0092] δ represents the current strain. For the strain increment, δ f The damage failure separation displacement under monotonic loading, where δ0 is the initial separation displacement under load. G is the cohesive fracture energy.

[0093] In one implementation of this embodiment, the method for updating the fatigue damage variable under cyclic loading in step S300 further includes:

[0094] S320. Import the nonlinear fatigue cohesion model into the pre-built three-dimensional thermo-mechanical coupling model.

[0095] In this embodiment, during the import of the nonlinear fatigue cohesive model into the COMSOL software, contact pairs can be inserted at the interfaces between the layers and plates of the track structure. The adhesion and peeling modules within the contact pairs can be set through secondary development to set important parameters of the high-cycle and low-cycle nonlinear fatigue cohesive models, such as interface strength, stiffness, and fracture energy. The three-dimensional thermo-mechanical coupling model in this embodiment can also be pre-built based on software such as ABAQUS and ANSYS.

[0096] In one implementation of this embodiment, the method for constructing the three-dimensional thermo-mechanical coupling model includes:

[0097] S321. Establish the solid unit of ballastless track;

[0098] S322. Nonlinear fatigue cohesive force model parameters are selected between vertical multi-layers of ballastless track and between longitudinal plates of ballastless track.

[0099] S323. Using finite element analysis software, establish three-dimensional thermo-mechanical coupling models of the scaled-down ballastless track model. The three-dimensional thermo-mechanical coupling model includes the thermo-mechanical coupling model under the heat conduction of low-cycle load and the dynamic action of high-cycle load.

[0100] S324. Calculate the thermodynamic response of the ballastless track under cyclic load coupling, compare and verify with the results of preset experiments or literature, and correct the three-dimensional thermodynamic coupling model.

[0101] In this embodiment, a solid element of the ballastless track is first established, comprising rails, fasteners, sleepers, track slabs, mortar layers, and a base plate. Then, the selected nonlinear fatigue cohesive model parameters are those between the vertical multi-layers of the ballastless track and between the longitudinal plates of the ballastless track; specifically, the parameters between the vertical multi-layers are those selected between the track slab, mortar layer, and base plate layers. Finally, using COMSOL's heat transfer and solid mechanics modules, a heat conduction model and a spatially refined dynamic model of the scaled-down ballastless track are established, respectively. These are then combined with the heat transfer, solid mechanics, and fatigue damage modules to establish a thermo-mechanical coupling model of the ballastless track structure. The thermo-mechanical response of the ballastless track under cyclic load coupling is calculated and compared with existing experimental or literature results (i.e., preset experimental or literature results) for verification. After correction, the three-dimensional thermo-mechanical coupling model is obtained.

[0102] In one implementation of this embodiment, the method for updating the fatigue damage variable under cyclic loading in step S300 further includes:

[0103] S330. Calculate the fatigue damage variables under cyclic loading.

[0104] In this embodiment, the calculation of fatigue damage variables under cyclic loading includes:

[0105] S331. Calculate the fatigue damage variables under each type of cyclic load, as well as the fatigue damage variables under all coupled cyclic loads.

[0106] Specifically, the fatigue damage variables include: temperature and stress fields at the ballastless track interface, relative displacement, axial forces at both ends, stiffness reduction, and damage factor.

[0107] In this embodiment, step S300 can calculate the fatigue damage variable under cyclic loading and the static damage variable under monotonic loading without cyclic loading. Using the fatigue damage variable and the static damage variable, the total interface damage variable can be calculated. The total interface damage variable is the sum of the fatigue damage variable and the static damage variable, or the larger value between the fatigue damage variable and the static damage variable.

[0108] Specifically, the fatigue damage variable and the static damage variable can be calculated using the following formula:

[0109] The initial displacement of the damage. This represents the displacement due to damage and failure.

[0110] Furthermore, the fatigue damage numerical calculation can be performed based on a three-dimensional thermo-mechanical coupling model of the ballastless track established by finite element analysis software. During the calculation, the control equations of heat conduction and stress field of the track structure can be solved by sequential coupling of finite element methods. The long and short cycle temperatures of the annual and daily temperature differences, the cycle duration of different train models, and the temperature conduction, stress field, and relative displacement of the ballastless track interface under the combined effect of these two factors can be calculated to obtain the corresponding parameters.

[0111] It is worth mentioning that the nonlinear fatigue cohesive model: the low-cycle fatigue cohesive model can draw on the irreversible damage model of the interface, and the high-cycle fatigue cohesive model can draw on the Peerling damage variable recognized in the field of interlaminar damage of composite materials and the Paris formula characterizing the crack propagation of metal fatigue. The damage evolution law with cycle number and strain (displacement) as parameters is selected to derive the fatigue cohesive model under high and low cycle loading, and the static damage variable and fatigue damage variable are combined to form a new constitutive relationship of the nonlinear fatigue cohesive model.

[0112] The three-dimensional thermo-mechanical coupling model of the ballastless track can take into account the effects of cyclic temperature and cyclic train load. The spatial refined thermo-mechanical coupling model of the ballastless track structure can be established by jointly using the heat transfer module, solid mechanics module and fatigue damage module of the finite element software.

[0113] The cumulative damage analysis method for ballastless track under cyclic loading can compare and analyze the temperature conduction, interface stress, interlayer deformation, interface damage factor and evolution process, and failure mode between the track slab and mortar layer under individual temperature cyclic loading, individual train cyclic loading, and coupled temperature and train load, to obtain the total damage variables.

[0114] In this embodiment, after calculating the total interface damage variable in step S300, the thresholds at which different cyclic loads begin to cause damage to the interface and the thresholds at which the interface completely fails can be determined based on the static damage variable under monotonic load, the fatigue damage variable under cyclic load, and the total interface damage variable.

[0115] Specifically, in this embodiment, fatigue damage analysis is used to compare and analyze the differences in temperature conduction, stress field, and relative displacement of the ballastless track interface under cyclic temperature, cyclic train, and the combined effect of both, as well as the differences in damage factors. This process characterizes the evolution of interfacial bonding performance under different cyclic loads from initial debonding, partial debonding to complete debonding, and reveals the evolution law of cumulative fatigue damage at the interface.

[0116] The following examples illustrate this embodiment:

[0117] Taking the high temperature of summer days as an example, the temperature cycle is between 30℃ and 40℃, with different temperature change rates of 10℃ / 24 hours, 10℃ / 12 hours, and 10℃ / 6 hours; the cyclic train load: for an 8-car train model, the number of cycles per year is about 3.5 million, the wheel weight is 170kN, the frequency is 25Hz, M-type wave, and the cyclic loading is 3.5 million times.

[0118] After setting the above environmental parameters and cyclic train load, fatigue analysis was performed using the nonlinear fatigue cohesion model of this embodiment, as follows: Figure 4 As shown, the specific steps include:

[0119] S11, Input track interface properties;

[0120] S12. Determine the current stress and displacement, determine the hybrid mode and failure displacement;

[0121] S13. Determine if the track interface is damaged; if yes, proceed to step S14; if no, end the analysis.

[0122] S14. Determine whether a cyclic load is applied; if no, proceed to step S15; if yes, proceed to steps S17a, S17b, and S17c simultaneously.

[0123] S15. Input the bilinear cohesive force model;

[0124] S16. Update the static damage variable and proceed to step S20.

[0125] S17a, Input a pre-built low-period nonlinear fatigue cohesive model; S17b, Input a pre-built high-period nonlinear fatigue cohesive model; S17c, Input a pre-built high- and low-period coupled nonlinear fatigue cohesive model;

[0126] S18. Import the nonlinear fatigue cohesion model into the pre-constructed three-dimensional thermo-mechanical coupling model;

[0127] S19. Update fatigue damage variables; where fatigue damage variables are calculated based on high-cycle cyclic load, low-cycle cyclic load, and high-low-cycle coupled cyclic load.

[0128] S20. Calculate the total damage variable; where the total damage variable is obtained based on the updated static damage variable and the updated fatigue damage variable;

[0129] S21. Determine if the total damage variable is invalid; if yes, end the analysis; if no, return to step S12.

[0130] like Figure 7As shown, analysis reveals that under the influence of temperature and train load, the fatigue damage at the ballastless track interface increases, meaning the relative displacement between layers increases; correspondingly, as... Figure 8 As shown, the geometric shape of ballastless track changes more and more under the influence of temperature and train load.

[0131] Compared with the prior art, the features and beneficial effects of the present invention are as follows:

[0132] This invention studies fatigue damage variables under individual high-cycle cyclic loading, individual low-cycle cyclic loading, and coupled high- and low-cycle cyclic loading. By comparing these fatigue damage variables under cyclic loading with static damage variables under monotonic loading and total interface damage variables, it is possible to determine the threshold at which different cyclic loads begin to cause damage to the interface and the threshold at which the interface completely fails. This allows for the analysis of the evolution of interfacial bonding performance and the cumulative fatigue damage of the interface under different high- and low-cycle cyclic loading.

[0133] Exemplary device

[0134] like Figure 9 As shown, another aspect of the present invention provides a device for analyzing the interface damage of ballastless track under high and low cycle cyclic load coupling, comprising: an input module 101, a judgment module 102, a calculation module 103 and an analysis module 104.

[0135] The input module 101 is used to input interface properties and determine the current stress and displacement, as well as the mixed mode and failure displacement.

[0136] The judgment module 102 is used to determine whether the ballastless track interface is damaged based on the current stress and displacement, mixed mode and failure displacement; and to determine whether to apply cyclic load.

[0137] The calculation module 103 is used to calculate the fatigue damage variables under cyclic loading, the static damage variables under monotonic loading, and the total interface damage variables.

[0138] The analysis module 104 is used to determine the threshold at which different cyclic loads begin to cause damage to the interface and the threshold at which the interface completely fails, based on the static damage variable under monotonic load, the fatigue damage variable under cyclic load, and the total interface damage variable.

[0139] Based on the above-mentioned method for analyzing interface damage of ballastless track under coupled high and low cycle loads, this invention also provides a terminal, such as... Figure 10As shown, the terminal includes at least one processor 20; a display screen; and a memory 22, and may also include a communication interface 23 and a bus 24. The processor 20, display screen, memory 22, and communication interface 23 can communicate with each other via the bus 24. The display screen is configured to show a preset user guide interface in the initial setup mode. The communication interface 23 can transmit information. The processor 20 can call logical instructions in the memory 22 to execute the methods described in the above embodiments.

[0140] Furthermore, the logical instructions in the aforementioned memory 22 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium.

[0141] The memory 22, as a computer-readable storage medium, can be configured to store software programs, computer-executable programs, such as program instructions or modules corresponding to the methods in the embodiments of this disclosure. The processor 20 executes functional applications and data processing by running the software programs, instructions, or modules stored in the memory 22, thereby implementing the methods in the above embodiments.

[0142] The memory 22 may include a program storage area and a data storage area. The program storage area may store the operating system and application programs required for at least one function; the data storage area may store data created based on the use of the terminal device. Furthermore, the memory 22 may include high-speed random access memory (RAM) and non-volatile memory. Examples include various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks, as well as transient storage media.

[0143] Furthermore, the specific process of loading and executing multiple instruction processors in the aforementioned storage medium and terminal device has been described in detail in the above method, and will not be repeated here.

[0144] Of course, the above description of the embodiments of the present invention is quite detailed, but it should not be construed as a limitation on the scope of protection of the present invention. The present invention may have many other implementations. Based on this implementation, other implementations obtained by those skilled in the art without any creative effort are all within the scope of protection of the present invention. The scope of protection of the present invention is determined by the appended claims.

Claims

1. A method for analyzing interface damage of ballastless track under coupled high and low periodic loads, characterized in that, include: Input track interface properties to determine the current stress and displacement, as well as the hybrid mode and failure displacement; Based on the current stress and displacement, hybrid mode and failure displacement, determine whether the ballastless track interface is damaged; If the interface is not yet damaged, update the static damage variable under continuous monotonic load or the fatigue damage variable under cyclic load. The cyclic loads include: individual high-cycle cyclic loads, individual low-cycle cyclic loads, and high-low-cycle cyclic loads; wherein, updating the fatigue damage variables under the cyclic loads includes: calculating the fatigue damage variables under the combined action of the individual high-cycle cyclic loads, the individual low-cycle cyclic loads, and the high-low-cycle cyclic loads; if the track interface is damaged, it is determined whether to apply cyclic loads. If no cyclic load is applied, update the static damage variable under monotonic load; if cyclic load is applied, update the fatigue damage variable under cyclic load; calculate the total interface damage variable based on the fatigue damage variable and the static damage variable. Based on the static damage variables under monotonic loading, the fatigue damage variables under cyclic loading, and the total interface damage variables, the thresholds for when different cyclic loads begin to cause damage to the interface and the thresholds for when the interface completely fails are determined. This includes comparing the fatigue damage variables under various cyclic loads with the static damage variables under monotonic loading and the total interface damage variables to determine the thresholds for when different cyclic loads begin to cause damage to the interface and the thresholds for when the interface completely fails. The evolution process of interface bonding performance and the evolution law of interface fatigue cumulative damage under different high and low cycle cyclic loads are analyzed.

2. The method for analyzing interface damage of ballastless track under coupled high and low cycle loads as described in claim 1, characterized in that, The updated fatigue damage variables under cyclic loading include: Input a pre-constructed nonlinear fatigue cohesion model; The nonlinear fatigue cohesion model is imported into the pre-constructed three-dimensional thermo-mechanical coupling model; Calculate the fatigue damage variables under cyclic loading.

3. The method for analyzing interface damage of ballastless track under coupled high and low cycle loads as described in claim 2, characterized in that, The method for constructing the nonlinear fatigue cohesive force model includes: deriving the formula for the nonlinear fatigue cohesive force model of the ballastless track interface based on the fatigue cohesive force model of the composite structure.

4. The method for analyzing interface damage of ballastless track under coupled high and low cycle loads according to claim 2, characterized in that, The method for constructing the three-dimensional thermo-coupling model includes: Establish ballastless track solid units; Nonlinear fatigue cohesive force model parameters are selected between the vertical multi-layers of the ballastless track and between the longitudinal plates of the ballastless track; Three-dimensional thermo-mechanical coupling models of ballastless track were established using finite element analysis software. The three-dimensional thermo-mechanical coupling models include heat conduction under low-cycle load and thermo-mechanical coupling models under dynamic action of high-cycle load. The thermodynamic response of the ballastless track under cyclic load coupling was calculated, and the results were compared with those from pre-set experiments or literature to verify and correct the three-dimensional thermodynamic coupling model.

5. The method for analyzing interface damage of ballastless track under coupled high and low cycle loads according to claim 2, characterized in that, The calculation of fatigue damage variables under cyclic loading includes: calculating the fatigue damage variables under each type of cyclic loading, and the total fatigue damage variables under all coupled cyclic loading.

6. The method for analyzing interface damage of ballastless track under coupled high and low cycle loads as described in claim 1, characterized in that, The fatigue damage variables include: temperature and stress fields at the ballastless track interface, relative displacement, axial forces at both ends, stiffness reduction, and damage factor.

7. The method for analyzing interface damage of ballastless track under coupled high and low cycle loads according to claim 1, characterized in that, The total interface damage variable is the sum of the fatigue damage variable and the static damage variable, or the larger value between the fatigue damage variable and the static damage variable.

8. The method for analyzing interface damage of ballastless track under coupled high and low cycle loads according to claim 1, characterized in that, The cyclic load includes at least temperature cyclic load and train cyclic load.

9. A device for analyzing interface damage of ballastless track under coupled high and low cycle loads, characterized in that, include: The input module is used to input track interface properties, determine the current stress and displacement, as well as the hybrid mode and failure displacement; The judgment module is used to determine whether the ballastless track interface is damaged based on the current stress and displacement, mixed mode and failure displacement; If the interface is not yet damaged, update the static damage variable under continuous monotonic load or the fatigue damage variable under cyclic load. The cyclic loads include: individual high-cycle cyclic loads, individual low-cycle cyclic loads, and high-low-cycle cyclic loads; wherein, updating the fatigue damage variables under the cyclic loads includes: calculating the fatigue damage variables under the combined action of the individual high-cycle cyclic loads, the individual low-cycle cyclic loads, and the high-low-cycle cyclic loads; if the track interface is damaged, it is determined whether to apply cyclic loads. The calculation module is used to update the static damage variable under monotonic load when no cyclic load is applied; and to update the fatigue damage variable under cyclic load when cyclic load is applied; and to calculate the total interface damage variable based on the fatigue damage variable and the static damage variable. The analysis module is used to determine the thresholds at which different cyclic loads begin to cause damage to the interface and the thresholds at which the interface completely fails, based on the static damage variables under monotonic loads, the fatigue damage variables under cyclic loads, and the total interface damage variables. This includes comparing the fatigue damage variables under various cyclic loads with the static damage variables under monotonic loads and the total interface damage variables to determine the thresholds at which different cyclic loads begin to cause damage to the interface and the thresholds at which the interface completely fails, and analyzing the evolution process of interfacial bonding performance and the evolution law of cumulative interface fatigue damage under different high and low cycle cyclic loads.

10. A terminal, comprising a memory and a processor, wherein the memory stores a computer-readable program executable by the processor; characterized in that, When the processor executes the computer-readable program, it implements the method for analyzing the interface damage of ballastless track under high and low cycle cyclic load coupling as described in any one of claims 1 to 8.

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