CN111339648B - High-speed railway turnout surface damage analysis method - Google Patents
High-speed railway turnout surface damage analysis method Download PDFInfo
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Abstract
The invention provides a method for analyzing surface damage of a turnout of a high-speed railway, which comprises the steps of calculating wheel load turnout passing and wheel load transfer through a vehicle-turnout model and a wheel-turnout steel rail model in a coupling manner, applying the load through a turnout combined steel rail local model, calculating the plastic deformation of a steel rail material, carrying out abrasion and fatigue accumulation, crack initiation and formation, crack expansion to a falling block or deep crack along with the passing frequency of a wheel, and finally making a maintenance strategy and parameters. According to the invention, through the formation and development of the surface damage of the turnout, the alternate change and the mutual influence of the surface wear and the crack development of the turnout steel rail under the action of the train load are reflected according to the sharing and transfer of the wheel load on the switch rail-basic rail, the point rail-wing rail, the wear change and the profile change of the switch rail-basic rail, the point rail and wing rail under the action of the load, the plastic deformation, the fatigue accumulation and the crack initiation and the expansion of the steel rail material.
Description
Technical Field
The invention relates to the field of rails, in particular to a railway turnout damage analysis method.
Background
The high-speed turnout is key line equipment for realizing switching of the high-speed train track, is the weakest part in the track structure, and is a main factor influencing traffic safety and limiting the speed of the train. At present, high-speed turnouts (special lines for passenger, CN and CZ) in China have been operated for about 10 years, the problem of contact fatigue damage of turnout steel rail pieces is gradually highlighted, the service life of the steel rail pieces is greatly shortened, even the operation safety of a high-speed railway is threatened, the contact damage of switch rails or point rails in a turnout area cannot be controlled in time, and once the turnout rails or point rails are broken, the switch rails and the point rails without buckling pressure can be in a free state, so that serious disastrous accidents are caused.
For the steel rail in the turnout zone of the high-speed railway, because the switch rail and the point rail have different sections, the switch rail-basic rail and the point rail-wing rail present different combination conditions at different positions, thus leading the vehicle-track interaction and the wheel rail contact relationship of the train passing through the turnout to be more complicated, and leading the steel rail to be more sensitive and obvious to contact fatigue damage. Aiming at the problem of contact fatigue damage of high-speed turnout wheel rails, related departments can carry out treatment by adopting measures such as material improvement, rail polishing, track geometric dimension adjustment and the like at present, but the contact fatigue damage still appears repeatedly and cannot be solved fundamentally.
The calculation of two types of damage of the conventional steel rail fatigue crack and abrasion is mostly considered independently, but from the mechanism, the crack can cause the surface material to break and separate from the base material to form fatigue abrasion. When the abrasion resistance of the steel rail is poor, metal around the cracks can be worn away, so that the cracks are eliminated or inhibited; otherwise, cracks remain in the rail skin material. Fatigue cracking and wear are therefore mutually influenced in coexistence by factors such as rail material properties, rail initial conditions, loads, wheel-rail geometry, wheel-rail contact, rail grinding and lubrication, friction control, rail geometry parameters, and system stiffness.
The method can calculate wheel load sharing and transfer, contact stress and adhesion-sliding effect by simulating vehicle-turnout power calculation, wheel-steel rail surface contact and position transfer when a vehicle passes through a turnout, respectively calculate the abrasion and fatigue of a steel rail material, further simulate the profile change and material fatigue damage accumulation under the condition of steel rail combination, and accordingly predict the fatigue crack and abrasion development of the turnout steel rail.
Disclosure of Invention
The invention considers the combination relation of basic rail-switch rail and point rail-wing rail when train passes through switch, load transfer and share, and the abrasion and profile change of switch combined rail under load action, and solves the problems of independent consideration, simultaneous existence, common development and mutual influence of crack and abrasion in the calculation of fatigue crack and abrasion of rail in the prior art.
The invention provides a method for analyzing surface damage of a turnout of a high-speed railway, which comprises the following steps of:
s1, extracting basic data of a vehicle and a track, and establishing a turnout coupling dynamic model of a high-speed train by using the basic data;
s2, carrying out wheel load calculation, wheel load transfer and sharing analysis according to the turnout coupling dynamic model of the high-speed train, and exporting results;
s3, establishing a turnout steel rail combination local model, and adding a wheel load calculation result and a wheel load transfer and sharing analysis result on the turnout steel rail combination local model;
s4, according to the turnout steel rail combination local model of the result of the additional wheel load calculation and the result of the wheel load transfer and sharing analysis, calculating plastic deformation, abrasion and fatigue of respective surface materials under the combination of the switch rail-basic rail and the point rail-wing rail under the action of shared load, and performing abrasion and fatigue accumulation along with the passing times of the wheels;
s5, calculating the service life and the position of crack initiation according to the position of the accumulated fatigue damage and the corresponding load times, adding a theoretical crack model or an actual measurement crack model at the switch rail-stock rail crack initiation position and the point rail-wing rail crack initiation position, and continuously simulating crack propagation under the conditions of load transfer and sharing;
and S6, if the crack is expanded to a certain degree, if the length and the depth reach certain numerical values, judging whether the deep crack occurs or the surface crack causes stripping and block falling, thereby making maintenance measures, carrying out rail change on the deep crack, polishing the surface crack which causes stripping and block falling, and simultaneously providing maintenance parameters, such as rail change time, polishing amount and the like.
The calculation under the coexistence condition of fatigue crack and abrasion of the turnout steel rail reflects the load sharing and transfer when the train passes through the turnout and the mutual influence on crack initiation, crack propagation and abrasion, and simultaneously can predict the crack initiation position, the initiation life and the propagation rate, the abrasion amount and the abrasion development rate, and the profile change of the turnout switch rail-basic rail, the point rail-wing rail, so as to guide the maintenance strategies of the turnout steel rail, such as rail changing time, polishing amount and the like.
The invention relates to a method for analyzing surface damage of a turnout of a high-speed railway, which is a preferred mode, and the step S4 specifically comprises the following steps:
s41, under the load action, the switch rail-stock rail and the point rail-wing rail respectively calculate the abrasion of the surface material according to the abrasion theory, subtracting the corresponding abrasion loss from each point of the initial profile to obtain the profile after abrasion, so that the profile changes of the switch rail-basic rail, the center rail-wing rail and the combined profile change;
s42, under the load action, respectively calculating the fatigue of the surface material according to a fatigue damage theory to obtain the fatigue damage distribution of the respective material and the fatigue accumulation of a certain number of wheels;
and S43, replacing the previous group of profiles when the profiles of the switch rail-stock rail and the point rail-wing rail change to a certain degree due to abrasion and reach a set abrasion threshold value, namely, the profiles change due to abrasion, and corresponding fatigue damage is accumulated to reflect the alternate change and mutual influence in abrasion and fatigue accumulation (crack initiation).
Calculating the plastic deformation, abrasion and fatigue of the material, and subsequently dividing the abrasion and fatigue accumulation into two items along with the passing times of the wheel: 1. the abrasion position and the accumulated development, the profile change (the basic rail and the switch rail are simultaneously changed according to the shared load and the abrasion caused by the load when the basic rail and the switch rail are combined), the profile change reaches the abrasion threshold value to form a new abrasion profile, and the original profile of the combined steel rail is replaced to continuously generate new abrasion; 2. fatigue formation, fatigue accumulation, accumulation of fatigue in new positions after profile replacement, fatigue to limit and position, crack initiation and position, and crack propagation.
Further, step S41 specifically includes:
s411, calculating the abrasion loss of the steel rail through an Archard abrasion model, wherein the formula is as follows:
wherein V w Volume to be abraded, k w As Archard abrasion coefficient, F N The contact normal force of the wheel track is used, s is the relative sliding distance of the wheel track contact spot interface, and H is the material hardness;
s412, calculating the abrasion loss of the section superposition: establishing position coordinates (x, y) of the contact patch, and calculating the abrasion loss of an inner point of the contact patch on the surface of the steel rail when the wheel passes through the upper section of the steel rail according to the following formula:
wherein, d y Dividing a wheel rail contact spot sliding area according to squares, and transversely numbering the total abrasion loss caused by the squares of the sliding area with the number of y; d is a radical of w (x, y) is the amount of wear at the grid (x, y); m is the total number of transverse unit grids of the contact patch; n is the total number of longitudinal unit grids of the contact patch;
further overlapping abrasion loss caused by the fact that 4 wheels of one section of the vehicle pass through the section to obtain the abrasion loss of the section of the stock rail and the section of the switch rail;
and S413, according to the abrasion loss obtained in the step S412, when the abrasion loss reaches an abrasion threshold, updating the profile, and selecting 6 basic control points for updating the profile: A. b, C, D, E, F, where point a is located 10mm from the center of the rail top of the stock rail on the non-gauge side; the point B is positioned on the stock rail and is level with the highest point C of the switch rail; according to the actually measured curved switch rail abrasion distribution on site, the point D can be positioned at the position 10mm below a rail distance measuring point on the switch rail; the point E and the point F are respectively the positions with the maximum abrasion depths of the stock rail and the switch rail; meanwhile, in the simulation service process, the position of the simulation platform is changed by combining field actual measurement and abrasion simulation;
in the ranges of A-B and C-D, generating basic rail and switch rail wear profiles smoothly by adopting a cubic spline interpolation curve, ensuring that the first-order derivatives at the starting point and the ending point are continuous in the solving process to ensure that the wear part is tangent to the curve of the rest part of the steel rail profile, and superposing the wear amount obtained by the Archard wear model in the step S411 on the steel rail profile to perform smoothing treatment;
s414, according to the total weight of the high-speed turnout preventive grinding cycle, if fatigue cracks are generated when the total weight of the turnout passes through the total weight of the grinding cycle in the simulation, the replacement of the profile caused by the grinding operation does not need to be additionally considered in the simulation process; and if the total weight reaches the total weight of the grinding period through simulation and cracks are not initiated, superposing the preventive grinding amount on the turnout steel rail profile to replace the profile.
And calculating the abrasion loss of the steel rail by the Archard abrasion model. In the Archard abrasion model, material abrasion only occurs in a contact spot sliding region, and the abrasion volume of the material is proportional to a normal force and a sliding distance and inversely proportional to the hardness of the material. The distribution of the abrasion depth of the steel rail in the contact patch range can be obtained.
Assuming that the wheel is in steady-state contact at a certain moment when the wheel runs on the rail in step S412, it can be considered that the contact state of the wheel and the rail is not changed at different moments when the wheel rolls over the vicinity of the section, that is, the contact stress, creep rate, creep force, contact patch area, adhesion area/sliding area, etc. on the contact patch are kept unchanged, and at this time, the wear amount of the section can be equivalent to the wear accumulation caused by the longitudinal movement of the contact patch, that is, the wear amount of each point on the longitudinal line segment of the sliding area. The 4 wheels of a section of vehicle are superposed through the abrasion loss caused by the section, and the difference of load sharing, load transfer and abrasion can be realized through the combination relationship of all the steel rails of the turnout.
Further, the fatigue calculating method in step S42 is to calculate the fatigue parameters according to the stress strain of each material point in the steel rail calculated by the finite element:
wherein σ 'and τ' are respectively LaThe tensile and shear fatigue strength coefficients, epsilon 'and gamma', respectively, the tensile and shear fatigue ductility coefficients, b is the fatigue strength index, c is the fatigue ductility index, P is R jmax is the maximum value of fatigue parameter of j point of rail at R rail profile, P R jmax is determined by:
wherein, the first and the second end of the pipe are connected with each other,<>is a bracket of MacCauley and is provided with a bracket,<σ max >＝0.5(|σ max |+σ max )，σ max the maximum positive stress on the crack surface, delta epsilon is the maximum value of the positive strain amplitude on all planes of each point caused when the wheel is in contact with the steel rail, delta tau and delta gamma are the maximum values of the shear stress amplitude and the shear strain amplitude on all planes of each point caused when the wheel is in contact with the steel rail respectively, and J is a material parameter.
The invention relates to a method for analyzing surface damage of a turnout of a high-speed railway, which is a preferred mode, and the step S1 specifically comprises the following steps:
s11, establishing a turnout integral model through vehicle track dynamics software;
s12, adding vehicle or wheel parameters, and establishing a high-speed train model;
and S13, coupling and assimilating the high-speed train model and the turnout integral model into a turnout coupling dynamic model of the high-speed train.
The method comprises the steps of establishing a high-speed rail vehicle and a turnout model through vehicle-track dynamics software, inputting a wheel profile and a steel rail profile as initial conditions of wheel-rail contact, and calculating the change, sharing and transfer conditions of a wheel-rail contact point when the vehicle passes a turnout. The turnout integral model and the high-speed train model are both physical data models, and the turnout power, wheel-rail contact, load sharing and transferring and impact load are calculated by coupling the turnout integral model and the high-speed train model, so that the turnout integral model and the high-speed train model are coupled into a three-dimensional entity model of a turnout coupling dynamic model of the high-speed train.
Further, the basic data includes vehicle parameters, turnout profiles, wheel profiles, turnout rail profiles, and train speeds.
The invention relates to a method for analyzing surface damage of a turnout of a high-speed railway, which is used as a preferred mode, wherein the results of wheel load calculation and wheel load transfer and sharing analysis are the wheel load transfer positions of wheel loads on a switch rail-basic rail and a point rail-wing rail, the sharing condition during transfer and the impact load condition of the wheel loads on the point rail-wing rail.
The invention relates to a method for analyzing surface damage of a turnout of a high-speed railway, which is a preferable mode, and the step S5 specifically comprises the following steps:
s51, obtaining the service life and the position of crack initiation according to the position (a certain point on a switch rail-stock rail, a point rail-wing rail reaches a fatigue limit value firstly) of the occurrence of the accumulated fatigue damage and the corresponding load times; simultaneously obtaining abrasion parameters such as abrasion loss, profile shape, abrasion development rate and the like;
s52, adding a theoretical crack model or an actually measured crack model at the crack initiation position on the switch rail-stock rail, the point rail-wing rail, and continuing to simulate the crack expansion under the conditions of load transfer and sharing according to the fracture mechanics theory;
and S53, in crack propagation, according to abrasion change and profile change of the point rail-stock rail and the point rail-wing rail caused by load, reducing the length and depth of the crack (the crack is worn away), and reflecting the alternate change and mutual influence in abrasion and crack propagation.
Furthermore, the crack propagation adopts a fracture mechanics theory and a Paris formula to calculate the stress intensity factor and the propagation rate of each point of the crack tip.
The invention has the following beneficial effects:
(1) When the profiles of the switch rail-basic rail, the point rail-wing rail change to a certain degree due to abrasion and reach a set abrasion threshold value, the previous profile is replaced, namely the abrasion causes the profile change, corresponding fatigue damage is accumulated, and the alternate change and the mutual influence in the abrasion and the fatigue accumulation (crack initiation) are reflected;
(2) Obtaining the service life and the position of crack initiation according to the position of the occurrence of accumulated fatigue damage (a certain point on a switch rail-stock rail, a point rail-wing rail reaches a fatigue limit value firstly) and the corresponding load times; simultaneously obtaining abrasion parameters such as abrasion loss, profile shape, abrasion development rate and the like;
(3) Adding a theoretical crack model or an actually measured crack model at the crack initiation position on the switch rail-stock rail, the point rail-wing rail, continuously simulating the crack expansion under the conditions of load transfer and sharing, and calculating the expansion rate, namely the crack length or depth reaches a certain numerical value after the load;
(4) During crack propagation, according to abrasion change and profile change of the switch rail-stock rail and the point rail-wing rail caused by load, the length and the depth of the crack are reduced (the crack is worn away), and alternate change and mutual influence in abrasion and crack propagation are reflected.
(5) And (3) if the crack is expanded to a certain degree, if the length and the depth reach certain numerical values, judging whether the deep crack or the surface crack causes stripping and block falling, thereby making maintenance measures, carrying out rail replacement on the deep crack, polishing the stripping and block falling caused by the surface crack, and simultaneously providing maintenance parameters, such as rail replacement opportunity, polishing amount and the like.
Drawings
FIG. 1 is a schematic diagram of a method for analyzing surface damage of a turnout of a high-speed railway.
Detailed Description
The technical solutions in the embodiments of the present invention will be made clear below with reference to the accompanying drawings in the embodiments of the present invention.
Example 1
As shown in fig. 1, a method for analyzing surface damage of a high-speed railway switch comprises the following steps:
s1, establishing a turnout integral model by Simpack \ Adams modeling and inputting vehicle parameters, a turnout line type, a wheel profile, a turnout steel rail profile and train speed;
s2, adding vehicle or wheel parameters, and establishing a high-speed train model;
s3, coupling and assimilating the high-speed train model and the turnout integral model into a turnout coupling dynamic model of the high-speed train;
the method comprises the steps of establishing a high-speed rail vehicle and turnout model through vehicle-track dynamics software, inputting wheel profile and steel rail profile as initial conditions of wheel-rail contact, and calculating the change, sharing and transfer conditions of wheel-rail contact points when the vehicle passes a turnout. The turnout integral model and the high-speed train model are both physical data models, and turnout power, wheel-rail contact, load sharing and transfer and impact load are calculated by coupling the turnout integral model and the high-speed train model, so that the turnout integral model and the high-speed train model are coupled into a three-dimensional entity model of the turnout coupling dynamic model of the high-speed train.
S4, carrying out wheel load calculation, wheel load transfer and sharing analysis according to the turnout coupling dynamic model of the high-speed train, and deriving and calculating wheel-rail force, wheel-rail contact positions, contact stress, adhesion-sliding states in contact spots, wheel pair transverse displacement and wheel load;
and wheel load calculation, wheel load transfer and sharing analysis are carried out, and a corresponding wheel rail contact position and a corresponding wheel rail force are obtained based on a Kalker wheel rail contact method.
S5, establishing a turnout steel rail combined local model, and adding a wheel load calculation result and a wheel load transfer and sharing analysis result on the turnout steel rail combined local model, namely calculating wheel rail force, a wheel rail contact position, contact stress, an adhesion-sliding state in a contact spot, wheel pair displacement and wheel load;
the turnout steel rail combination model is obtained by intercepting a turnout switch rail-stock rail combination model of one section (a section with serious actual measurement abrasion and crack), namely intercepting a three-dimensional entity model under the combination of the switch rail-stock rail and the center rail-wing rail, wherein the profile is obtained by actual measurement or a design drawing. Further calculation can obtain Qu Jiangui rail head stress strain magnitude and distribution.
S6, calculating the abrasion loss of the steel rail through an Archard abrasion model, wherein the formula is as follows:
wherein V w Volume to be abraded, k w Is Archard abrasion coefficient, F N Normal force for wheel-rail contact, sThe relative sliding distance of the wheel track contact spot interface is shown, and H is the material hardness;
s7, calculating the abrasion loss of the section superposition: establishing position coordinates (x, y) of the contact patch, and calculating the abrasion loss of an inner point of the contact patch on the surface of the steel rail when the wheel passes through the upper section of the steel rail according to the following formula:
wherein d is y Dividing a wheel rail contact spot sliding area according to squares, wherein the total abrasion loss is caused by the sliding area squares which are transversely numbered as y; d w (x, y) is the amount of wear at the grid (x, y); m is the total number of contact patch transverse unit grids; n is the total number of longitudinal unit grids of the contact patch;
further overlapping abrasion loss caused by the fact that 4 wheels of one section of the vehicle pass through the section to obtain the abrasion loss of the section of the stock rail and the section of the switch rail;
s8, according to the abrasion loss obtained in the step S7, when the abrasion loss reaches an abrasion threshold value, carrying out profile updating, and selecting 6 basic control points for profile updating: A. b, C, D, E, F, where point a is located 10mm from the center of the rail top of the stock rail on the non-gauge side; the point B is positioned on the stock rail and is level with the highest point C of the switch rail; according to the actually measured abrasion distribution of the curved switch rail on site, the point D can be positioned at the position 10mm below a measuring point of the distance between the upper rail and the point of the switch rail; the point E and the point F are respectively the positions with the maximum abrasion depths of the stock rail and the switch rail; meanwhile, in the simulation service process, the position of the simulation platform is changed by combining field actual measurement and abrasion simulation;
in the range from A to B and the range from C to D, generating the wear profiles of the stock rail and the switch rail smoothly by adopting a cubic spline interpolation curve, ensuring that the first-order derivatives at the starting point and the ending point are continuous in the solving process to ensure that the wear part is tangent with the curve of the rest part of the steel rail profile, and superposing the wear amount obtained by the Archard wear model of the step S411 on the steel rail profile for smoothing;
s9, taking the total weight of 30Mt as a preventive grinding period of the high-speed turnout as an example, if fatigue cracks are generated when the total weight of 30Mt is not reached in simulation, the replacement of the profile caused by grinding operation does not need to be additionally considered in the simulation process; if cracks do not grow when the total weight reaches 30Mt in fatigue simulation, superposing preventive grinding amount (taking the grinding amount of the rail top center as 0.1mm as an example) to the turnout steel rail profile for profile replacement;
s10, respectively calculating the fatigue of surface materials under the load action of the updated switch rail-stock rail and the center rail-wing rail to obtain the fatigue damage distribution and fatigue accumulation of the respective materials;
the fatigue calculation method is that the stress strain of each material point in the steel rail is calculated according to the finite element, and the fatigue parameters are calculated:
wherein, sigma 'and tau' are respectively tensile and shear fatigue strength coefficients, epsilon 'and gamma' are respectively tensile and shear fatigue ductility coefficients, b is a fatigue strength index, c is a fatigue ductility index, P is R jmax is the maximum value of fatigue parameter of j point of rail at R rail profile, P R jmax is determined by:
wherein the content of the first and second substances,<>is a bracket of MacCauley and is provided with a bracket,<σ max >＝0.5(|σ max |+σ max )，σ max the maximum positive stress on the crack surface, delta epsilon is the maximum value of the positive strain amplitude on all planes of each point caused when the wheel is in contact with the steel rail, delta tau and delta gamma are the maximum values of the shear stress amplitude and the shear strain amplitude on all planes of each point caused when the wheel is in contact with the steel rail respectively, and J is a material parameter.
S11, replacing the previous group of profiles when the profiles of the switch rail-stock rail and the point rail-wing rail change to 0.04mm due to abrasion;
s12, acquiring a crack initiation position according to the position where the accumulated fatigue damage occurs and the corresponding load times; simultaneously obtaining abrasion parameters such as abrasion loss, profile shape, abrasion development rate and the like;
s13, adding a theoretical crack model or an actual measurement crack model at the point rail-stock rail crack initiation position and the point rail-wing rail crack initiation position, and continuing to simulate crack expansion under the conditions of load transfer and sharing according to a fracture mechanics theory;
the theoretical crack model or the actual measurement crack model is a preset crack three-dimensional solid model.
S14, in crack propagation, according to abrasion change and profile change of a switch rail-stock rail, a point rail-wing rail caused by load, the length and the depth of cracks are reduced;
s15, judging whether deep cracks or surface cracks cause stripping and block falling according to the crack propagation condition, thereby making maintenance measures, carrying out rail replacement on the deep cracks, polishing the surface cracks causing stripping and block falling, and simultaneously proposing maintenance parameters.
As an example, when the crack propagation angle is positive (in the direction toward the rail surface) in the longitudinal direction of the crack, it is considered that the crack causes separation and chipping, and when the crack propagation angle is negative in the longitudinal direction of the crack, it is considered that the crack propagates into the rail. Further determining the grinding amount according to the depth and the range of the crack; the length and depth of the crack determine whether to grind or change the rail; the crack growth rate determines the timing of the rail change or grinding. The crack propagation adopts the fracture mechanics theory and the Paris formula to calculate the stress intensity factor and the propagation rate of each point of the crack tip.
The basic data comprises vehicle parameters, turnout line types, wheel profile shapes, turnout steel rail profile shapes and train speeds.
The results of the wheel load calculation and the results of the wheel load transfer and sharing analysis are the wheel load transfer positions and the sharing conditions during transfer of the wheel loads on the switch rail-stock rail and the point rail-wing rail, and the impact load conditions during transfer of the wheel loads on the point rail-wing rail are obtained.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.
Claims (9)
1. A method for analyzing surface damage of a high-speed railway turnout is characterized by comprising the following steps: the method comprises the following steps:
s1, extracting basic data of a vehicle and a track, and establishing a turnout coupling dynamic model of a high-speed train by using the basic data;
s2, carrying out wheel load calculation, wheel load transfer and sharing analysis according to the turnout coupling dynamic model of the high-speed train, and exporting results;
s3, establishing a turnout steel rail combination local model according to the result of the step S2, and adding the wheel load calculation result and the wheel load transfer and sharing analysis result to the turnout steel rail combination local model;
s4, according to the turnout steel rail combination local model added with the result of the wheel load calculation and the result of the wheel load transfer and sharing analysis, calculating plastic deformation, abrasion and fatigue of respective surface materials under the combination of the switch rail-stock rail and the point rail-wing rail under the effect of shared load, and carrying out abrasion and fatigue accumulation along with the passing times of the wheels;
s5, calculating the service life and the position of crack initiation according to the position of the accumulated fatigue damage and the corresponding load times, adding a theoretical crack model or an actual measurement crack model into the crack initiation position of the switch rail-stock rail and the crack initiation position of the center rail-wing rail, and continuing to simulate the crack expansion under the conditions of load transfer and sharing;
and S6, judging whether deep cracks or surface cracks cause stripping and block dropping according to the crack propagation condition, thereby making maintenance measures, carrying out rail replacement on the deep cracks, polishing the surface cracks causing stripping and block dropping, and simultaneously proposing maintenance parameters.
2. The method for analyzing the surface damage of the turnout of the high-speed railway according to claim 1, wherein the method comprises the following steps: the step S4 specifically includes:
s41, respectively calculating the abrasion of the surface material under the load action of the switch rail-stock rail and the point rail-wing rail, and subtracting the corresponding abrasion amount from each point of the initial profile to obtain the profile after abrasion;
s42, respectively calculating the fatigue of surface materials under the load action of the switch rail-stock rail and the point rail-wing rail updated in the step S41 to obtain the fatigue damage distribution and fatigue accumulation of respective materials;
and S43, replacing the previous group of profiles when the switch rail-stock rail and point rail-wing rail profiles change to the set abrasion threshold value due to abrasion.
3. The method for analyzing the surface damage of the turnout of the high-speed railway according to claim 2, wherein the method comprises the following steps: the step S41 specifically includes:
s411, calculating the abrasion loss of the steel rail through an Archard abrasion model, wherein the formula is as follows:
wherein V w Volume to be abraded, k w Is Archard abrasion coefficient, F N The contact normal force of the wheel track is adopted, s is the relative sliding distance of the wheel track contact spot interface, and H is the material hardness;
s412, calculating the abrasion loss of the section superposition: establishing position coordinates (x, y) of the contact patch, and calculating the abrasion loss of an inner point of the contact patch on the surface of the steel rail when the wheel passes through the upper section of the steel rail according to the following formula:
wherein d is y Dividing a wheel rail contact spot sliding area according to squares, wherein the total abrasion loss is caused by the sliding area squares which are transversely numbered as y; d is a radical of w (x, y) is the amount of wear at the grid (x, y); m is the total number of contact patch transverse unit grids; n is the total number of longitudinal unit grids of the contact patch;
further overlapping abrasion loss caused by the fact that 4 wheels of one section of the vehicle pass through the section to obtain the abrasion loss of the section of the stock rail and the section of the switch rail;
and S413, according to the abrasion loss obtained in the step S412, when the abrasion loss reaches an abrasion threshold, updating the profile, and selecting 6 basic control points for updating the profile: A. b, C, D, E, F, where point a is located 10mm from the center of the rail top of the stock rail on the non-gauge side; the point B is positioned on the stock rail and is level with the highest point C of the switch rail; according to the actually measured abrasion distribution of the curved switch rail on site, the point D can be positioned at the position 10mm below a measuring point of the distance between the upper rail and the point of the switch rail; points E and F are respectively the positions with the maximum abrasion depths of the stock rail and the switch rail; meanwhile, in the simulation service process, the position of the simulation platform is changed by combining field actual measurement and abrasion simulation;
in the ranges of A-B and C-D, generating basic rail and switch rail wear profiles smoothly by adopting a cubic spline interpolation curve, ensuring that the first-order derivatives at the starting point and the ending point are continuous in the solving process to ensure that the wear part is tangent to the curve of the rest part of the steel rail profile, and superposing the wear amount obtained by the Archard wear model in the step S411 on the steel rail profile to perform smoothing treatment;
s414, according to the total weight of the high-speed turnout preventive grinding cycle, if fatigue cracks are generated when the total weight of the turnout passes through the total weight of the grinding cycle in the simulation, the replacement of the profile caused by the grinding operation does not need to be additionally considered in the simulation process; and if cracks are not initiated yet when the total weight reaches the total weight of the grinding period in the simulation, superposing the preventive grinding amount on the turnout steel rail profile to replace the profile.
4. The method for analyzing the surface damage of the turnout of the high-speed railway according to claim 2, wherein the method comprises the following steps: the fatigue calculation method in the step S42 is to calculate the fatigue parameters according to the stress strain of each material point in the steel rail calculated by finite elements:
wherein, sigma ' and tau ' are respectively tensile and shearing fatigue strength coefficients, epsilon ' and gamma' respective tensile and shear fatigue ductility coefficient, b is fatigue strength index, c is fatigue ductility index, P R jmax is the maximum value of the fatigue parameter of the j point of the steel rail when the R-th steel rail molded surface is formed, and P is R jmax is determined by:
wherein the content of the first and second substances,<>is shown in the parentheses of MacCauley,<σ max >＝0.5(|σ max |+σ max )，σ max the maximum positive stress on the crack surface, delta epsilon is the maximum value of the positive strain amplitude on all planes of each point caused when the wheel is contacted with the steel rail, delta tau and delta gamma are the maximum values of the shear stress amplitude and the shear strain amplitude on all planes of each point caused when the wheel is contacted with the steel rail respectively, and J is a material parameter.
5. The method for analyzing the surface damage of the turnout of the high-speed railway according to claim 1, wherein the method comprises the following steps: the step S1 specifically includes:
s11, establishing a turnout integral model through vehicle track dynamics software;
s12, adding vehicle or wheel parameters, and establishing a high-speed train model;
and S13, coupling and unifying the high-speed train model and the turnout integral model into a turnout coupling dynamic model of the high-speed train.
6. The method for analyzing the surface damage of the turnout of the high-speed railway according to claim 5, wherein the method comprises the following steps: the basic data comprises vehicle parameters, turnout line types, wheel profile shapes, turnout steel rail profile shapes and train speeds.
7. The method for analyzing the surface damage of the turnout of the high-speed railway according to claim 1, wherein the method comprises the following steps: the results of the wheel load calculation and the results of the wheel load transfer and sharing analysis are the wheel load transfer positions of the wheel loads on the switch rail-basic rail and the point rail-wing rail, the wheel load sharing conditions during transfer and the impact load conditions of the wheel loads on the point rail-wing rail.
8. The method for analyzing the surface damage of the turnout of the high-speed railway according to claim 1, wherein the method comprises the following steps: step S5 specifically includes:
s51, acquiring a crack initiation position according to the position where the accumulated fatigue damage occurs and the corresponding load times; simultaneously obtaining abrasion parameters such as abrasion loss, profile shape, abrasion development rate and the like;
s52, adding a theoretical crack model or an actually measured crack model at the point rail-stock rail crack initiation position and the point rail-wing rail crack initiation position, and continuing to simulate crack propagation under the conditions of load transfer and sharing according to a fracture mechanics theory;
and S53, in crack propagation, the length and the depth of the crack are reduced according to abrasion change and profile change of the point rail-stock rail and the point rail-wing rail caused by load.
9. The method for analyzing the surface damage of the turnout of the high-speed railway according to claim 8, wherein the method comprises the following steps: the crack propagation adopts a fracture mechanics theory and a Paris formula to calculate the stress intensity factor and the propagation rate of each point of the crack tip.
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