Method for determining service performance demand of steel rail

Abstract

The invention discloses a method for determining the service performance requirement of a steel rail. The method comprises the following steps of: 1, acquiring service state parameters of the steel rail; 2, establishing a simulation analysis model; 3, predicting steel rail service performance development; 4, performing dynamic calculation to obtain a result; 5, establishing a steel rail service performance demand model; and 6, the steel rail performance improvement requirement is proposed. The steel rail performance requirement design method provided by the invention makes up the defects in the aspect of material selection and use of the current railway steel rail. According to the method, the specific characteristics of steel rail service are combined, the line shape, speed, abrasion, damage, corrosion states and the like are comprehensively considered, the steel rail performance requirement suitable for the characteristics is given through simulation calculation and theoretical analysis, and detailed and specific reference and guidance can be provided for steel rail component design.

Description

Technical Field

[0001] The invention belongs to the technical field of railway rail detection and relates to a method for determining service performance requirements of rails. Background Art

[0002] my country's high-speed and plateau railways are long in mileage and span. Under different line conditions, the development and evolution of rail wear and damage are also quite different. It is difficult for rail service performance to coordinate well with on-site needs, which restricts the continuous improvement of rail safety and life. Therefore, when designing rail performance, it is necessary to combine specific service scenarios, give full consideration to its application conditions and application scenarios, comprehensively consider the coordination of multiple parameters of material performance indicators, and the coordination of material performance and component service durability, and propose the improvement requirements of various rail service performance.

[0003] The existing technology for selecting rails for high-speed railways is mainly based on the line radius and speed level, while for conventional railways it is mainly based on annual transportation volume and curve radius. It does not take into account the service status and demand of the line, and cannot balance the relationship between strength and toughness;

[0004] At the same time, the demand for rail service performance is not fully considered, and the demand for rail service performance cannot be quantified. The demand for each performance is not fully analyzed, the demand is not quantified, and the correlation between various service performances cannot be considered. Summary of the invention

[0005] In order to overcome the above-mentioned defects of the prior art, the present invention proposes a method for determining the service performance requirements of rails.

[0006] A method for determining rail service performance requirements, the method comprising:

[0007] Step 1: Collect rail service status parameters;

[0008] Step 2: Establish a simulation analysis model;

[0009] Step 3: Prediction of rail service performance development;

[0010] Step 4: Kinetic calculation results;

[0011] Step 5: Establish rail service performance demand model;

[0012] Step 6: Propose requirements for improving rail performance.

[0013] The rail service status parameters collected in step 1 include two types: line parameters and rail parameters. The line parameters refer to the type of line (straight line, curve), linear parameters (curve radius, superelevation), operating conditions, and operating vehicle information on which the rail is located; the rail parameters refer to the rail material type, rail profile, smoothness, and damage characteristics, among which smoothness mainly focuses on joint straightness and corrugation, and damage mainly includes contact fatigue-related damage such as abrasions, oblique cracks, fish scales, and rust.

[0014] Among them, the simulation analysis model established in the step 2 is to establish the dynamic models of conventional trains and high-speed trains respectively according to the different needs of conventional and high-speed railways. The vehicle model is wheelset-bogie-car body from bottom to top. The normal contact between the wheel and the rail is calculated using Hertz elastic contact theory, and the tangential force is calculated using Kalker's simplified algorithm FASTSIM. The suspension system between the wheelset and the frame, and between the frame and the car body are simulated by spatial spring damping force elements. The bogie as a whole is composed of a virtual car body, wheelset, frame, front and rear beams, and the stop force and anti-snaking shock absorber unloading speed take into account their nonlinear characteristics.

[0015] The prediction of the development of rail service performance in step 3 includes prediction of rail wear development, prediction of rail contact fatigue damage crack propagation and prediction of rail corrosion development. The prediction of rail wear development requires the establishment of a rail wear development prediction model. First, the actual line and vehicle parameters on site are input into the vehicle-track coupling dynamics model, and the Archard wear formula is used to calculate the wheel-rail wear. The Archard wear formula is:

[0016]

[0017] In the formula, V represents the wear amount, which is the calculation output result. H represents the hardness of the side with higher hardness between the wheel and rail. Other parameters are calculated by the simulation analysis model established in step 2:

[0018] N represents the normal force of wheel-rail contact, Δs represents the relative sliding distance, k1~k4 represent the wear coefficient, p represents the contact stress, f represents the contact pressure stress limit ratio, v1 and v2 represent the relative sliding speeds of the two boundaries,

[0019] After setting the wear parameters, the wear calculation can be performed. Each calculation will get the rail wear amount. For the first step of calculation, the wear amount is subtracted from the original rail profile to get the rail profile after wear. The rail profile after wear is substituted into the simulation calculation model and calculated again. And so on, the rail profile under different total weight conditions is obtained.

[0020] In the prediction of the contact fatigue damage crack growth of the rail, the contact fatigue damage resistance of the rail is mainly reflected in the performance of resisting fatigue crack growth. When predicting crack growth, the crack with an initial elliptical shape is considered. First, the critical threshold of crack growth under the conditions of rails with different wear resistance is calculated according to the formula, and then the variables are separated, and the two sides are integrated to solve the relationship between the crack growth rate and the total weight passing. The formula is:

[0021]

[0022] Where a represents the crack depth, 2c represents the crack width, and d represents the distance between the upper surface of the crack and the top surface of the rail. is the net crack growth rate, w is the rail wear rate under the conditions of rapid grinding and large machine grinding, β is the crack growth angle,

[0023] is the crack growth rate, which is calculated as:

[0024]

[0025] In the formula, C and p are material test constants.

[0026] ΔK eff is the stress intensity factor amplitude, and the calculation formula is:

[0027]

[0028] Φ is [1-(a / c) 2 ] is the second kind of elliptic integral, λ represents the geometric effect factor, Δσ represents the stress amplitude, and a represents the crack length;

[0029] The calculation formula of Δσ is:

[0030]

[0031] In the formula, σ y represents the horizontal shear stress on the rail surface above the crack surface, σ z represents the normal stress in the vertical direction of the rail surface above the crack surface,

[0032] τ xz represents the shear stress, and the calculation formula is:

[0033]

[0034] Where m0 is related to the wheel-rail profile, P represents the wheel-rail vertical force, E represents the rail elastic modulus, r1 represents the arc radius of the vehicle profile,

[0035] The prediction of rail corrosion development is mainly reflected in that as the service time increases, the thickness of the rail waist and rail bottom is gradually reduced by corrosion. According to the line maintenance rules, the criteria for determining serious damage of rail corrosion mainly include the thickness of the rail bottom and rail waist. Therefore, the development rate of rail corrosion is determined by the change in the thickness of the rail bottom and rail waist before and after rust removal, divided by the actual service life. The formula is:

[0036]

[0037] Where, [W] represents the standard rail waist thickness before rust removal, W w represents the rail waist thickness after rust removal, L represents the service life of the rail, [T] represents the standard rail bottom thickness before rust removal, T f Indicates the rail bottom thickness after rust removal.

[0038] Among them, the dynamic calculation results of step 4 are that the rail service performance development prediction model established in step 3 needs to be calculated based on the calculation results of the dynamic model in step 2 as initial conditions. This step sorts out the dynamic calculation results.

[0039] Wherein, the step 5 of establishing the rail service performance demand model needs to calculate the rail wear resistance, rail contact fatigue damage resistance and rail corrosion resistance parameters, wherein the rail wear resistance needs to be combined with the balance relationship between the natural wear rate of the rail on site and the fatigue damage development rate, to clarify whether the rail wear resistance needs to be improved or reduced, and then calculate the rail profile after wear within an overhaul cycle or a large machine grinding cycle under the conditions of a 10%, 20%, and 30% improvement in wear resistance according to the rail wear development prediction model;

[0040] The contact fatigue damage resistance of the rails is generally within 0.2 mm, and the critical damage standard of the crack depth of high-speed rails is 1 mm. The crack growth prediction model is used to calculate the crack growth rate at different initial depths. By improving the contact fatigue damage resistance and reducing the initial crack depth, the crack growth rate extending to a depth of 1 mm is controlled at a stable development stage. The improvement requirements of the contact fatigue damage resistance are calculated according to the following formula:

[0041]

[0042] Where, d i Indicates the acceptable initial contact fatigue damage crack depth. For conventional railways, the contact fatigue damage depth is generally around 1 mm. Therefore, when designing the anti-contact fatigue damage performance, the anti-contact fatigue damage performance improvement requirement is calculated according to the following formula:

[0043]

[0044] The rail corrosion resistance can be preliminarily estimated based on the thickness of the rail bottom and rail waist after rust removal in the relevant standards. Considering that the rail overhaul cycle is 30 years, the corrosion resistance improvement calculation method is (1-allowable corrosion rate / actual corrosion rate)×100%, and the rail corrosion resistance requirement is calculated:

[0045]

[0046] In the formula, y c represents the rail corrosion resistance requirement, c f represents the rail bottom corrosion rate, c w represents the rail waist corrosion rate, L represents the service life of the rail, c r Indicates the actual corrosion rate of the rail.

[0047] Among them, the step 6 proposes the demand for improving rail performance according to the calculated and analyzed service performance of each rail, and finally proposes a total rail performance improvement demand plan.

[0048] Optionally, step 2 is to obtain the kinetic index results of step 3 and provide parameter basis for step 4. It can also be replaced by a simulation model established by other methods, such as finite element method, but the calculated and output results are the same.

[0049] Optionally, in step 3, the rail wear development prediction method is calculated using the Archard wear formula, which is mainly used to provide a basis for determining the rail wear resistance in step 5. The Kraus / Poll and Zobory wear methods can also be used as substitutes, but the calculation results are the same.

[0050] Optionally, in step 3, the rail contact fatigue damage crack growth prediction method may also be replaced by other programs or methods, with the same calculation results.

[0051] Optionally, in step 4, when calculating and determining the service performance requirements of the rail, the control thresholds of various service performances can be adjusted. For example, for the resistance to contact fatigue damage performance, the initial crack depth control threshold can be set to 0.12 or 0.15 mm according to actual needs. The demand for the resistance to contact fatigue damage performance will change, but the adjustment of the threshold itself only adapts the performance requirement result.

[0052] The present invention proposes a method for designing rail performance requirements, which makes up for the current deficiencies in the selection and use of railway rail materials. The present invention combines the specific characteristics of rail service, comprehensively considers linearity, speed, wear, damage, and corrosion status, and provides rail performance requirements suitable for the characteristics through simulation calculations and theoretical analysis, which can provide detailed and specific reference and guidance for rail component design. The present invention considers the specific service and use environment of rails in a more comprehensive and detailed manner, and further combines simulation and theoretical analysis to establish a development prediction model for various service performances, and comprehensively considers relevant specifications and standards to clarify the specific requirements for rail service performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 Schematic diagram of the technical route for design method of rail performance requirements.

[0054] Figure 2 Schematic diagram of a crack in a rail with an initial elliptical shape.

[0055] Figure 3 Schematic diagram of profile deviation calculation at different positions. DETAILED DESCRIPTION

[0056] A method for determining rail service performance requirements provided by the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0057] Figure 1 As shown, a method for determining the service performance requirements of rails, the method comprising:

[0058] Step 1: Collect rail service status parameters;

[0059] Step 2: Establish a simulation analysis model;

[0060] Step 3: Prediction of rail service performance development;

[0061] Step 4: Kinetic calculation results;

[0062] Step 5: Establish rail service performance demand model;

[0063] Step 6: Propose requirements for improving rail performance.

[0064] The rail service status parameters collected in step 1 include two types: line parameters and rail parameters. The line parameters refer to the line type (straight line, curve), line parameters (curve radius, superelevation), operating conditions, and operating vehicle information of the rails. The details are shown in Table 1:

[0065]

[0066] Table 1 Rail lines and running vehicle information

[0067] Rail parameters refer to rail material type, rail profile, smoothness and damage characteristics, among which smoothness mainly focuses on joint straightness and corrugation, and damage mainly includes contact fatigue related damage such as abrasions, oblique cracks, fish scales and rust. The details are shown in Table 2:

[0068]

[0069] Table 2 Rail parameters and damage characteristics

[0070] In the mileage range, the "KXXX" in "KXXX+XXX" indicates the kilometer mark where the rail is located, and the "+XXX" indicates the specific location of the rail, accurate to meters; for example, K123+300~K125+500 means that the rail is located between 123.3 kilometers and 135.5 kilometers.

[0071] Among them, the simulation analysis model established in the step 2 is to establish the dynamic models of conventional trains and high-speed trains respectively according to the different needs of conventional and high-speed railways. The vehicle model is wheelset-bogie-car body from bottom to top. The normal contact between the wheel and the rail is calculated using Hertz elastic contact theory, and the tangential force is calculated using Kalker's simplified algorithm FASTSIM. The suspension system between the wheelset and the frame, and between the frame and the car body are simulated by spatial spring damping force elements. The bogie as a whole is composed of a virtual car body, wheelset, frame, front and rear beams, and the stop force and anti-snaking shock absorber unloading speed take into account their nonlinear characteristics.

[0072] The prediction of the development of rail service performance in step 3 includes prediction of rail wear development, prediction of rail contact fatigue damage crack propagation and prediction of rail corrosion development. The prediction of rail wear development requires the establishment of a rail wear development prediction model, such as Figure 2 As shown in the figure, the actual line and vehicle parameters on site are first input into the vehicle-track coupling dynamics model, and the wheel-rail wear is calculated using the Archard wear formula, which is:

[0073]

[0074] In the formula, V represents the wear amount, which is the calculation output result. H represents the hardness of the side with higher hardness between the wheel and rail. Other parameters are calculated by the simulation analysis model established in step 2:

[0075] N represents the normal force of wheel-rail contact, Δs represents the relative sliding distance, and k1~k4 represent the wear coefficients. Figure 2Determine, p represents the contact stress, f is the contact pressure stress limit ratio, v1 and v2 represent the relative sliding speeds of the two boundaries, and the wear calculation can be performed after the wear parameters are set. Each calculation will get the rail wear amount. For the first step of calculation, the wear amount is subtracted from the original rail profile to get the rail profile after wear; the rail profile after wear is substituted into the simulation calculation model, and the calculation is performed again, and so on, to get the rail profile under different total weight conditions;

[0076] In the prediction of rail contact fatigue crack growth, Figure 3 As shown in the figure, the anti-contact fatigue damage performance of the rail is mainly reflected in the performance of resisting fatigue crack propagation. When predicting crack propagation, the crack with an initial elliptical shape is considered. First, the critical threshold of crack propagation under different wear-resistant rail conditions is calculated according to the formula (that is, when the initial crack depth exceeds this value, it will gradually expand under the action of train load, and when the initial crack depth is lower than this value, it will gradually disappear under the action of wear). Then separate the variables, integrate both sides, and solve the relationship between the crack propagation rate and the total weight passing. The formula is:

[0077]

[0078] Figure 3 As shown in the figure, a represents the crack depth, 2c represents the crack width, and d represents the distance between the upper surface of the crack and the rail top. Because the damage starts from the rail top and develops downward, d = 0. is the net crack growth rate, w is the rail wear rate under the conditions of rapid grinding and large machine grinding, β is the crack growth angle,

[0079] is the crack growth rate, which is calculated as:

[0080]

[0081] In the formula, C and p are material test constants, which are related to factors such as material, stress ratio, and environment. According to relevant literature, for U71Mn rail, p is taken as 2.88 and C is taken as 4.597×10 -13 ,

[0082] ΔK eff is the stress intensity factor amplitude, and the calculation formula is:

[0083]

[0084] Φ is [1-(a / c) 2 ], λ represents the geometric effect factor. When the normal stress direction and the shear stress direction are perpendicular and parallel to the crack slope, respectively, λ is taken I =λII =1.12, Δσ represents the stress amplitude, i.e. the difference between the maximum stress and the minimum stress, and a represents the crack length;

[0085] The calculation formula of Δσ is:

[0086]

[0087] In the formula, σ y represents the horizontal shear stress on the rail surface above the crack surface, σ z It represents the normal stress in the vertical direction of the rail surface above the crack surface. Both need to be obtained through simulation calculation of wheel-rail contact theory.

[0088] τ xz represents the shear stress, and the calculation formula is:

[0089]

[0090] In the formula, m0 is related to the wheel-rail profile. For the LMB10 and 60N profile matching, m0 = 0.5 can be taken, which represents the wheel-rail vertical force (maximum shear force), P represents the wheel-rail vertical force, E represents the elastic modulus of the rail, r1 represents the arc radius of the vehicle profile,

[0091] The prediction of rail corrosion development is mainly reflected in that as the service time increases, the thickness of the rail waist and rail bottom is gradually reduced by corrosion. According to the line maintenance rules, the criteria for determining serious damage of rail corrosion mainly include the thickness of the rail bottom and rail waist. Therefore, the development rate of rail corrosion is determined by the change in the thickness of the rail bottom and rail waist before and after rust removal, divided by the actual service life. The formula is:

[0092]

[0093] Where, [W] represents the standard rail waist thickness before rust removal, W w represents the rail waist thickness after rust removal, L represents the service life of the rail, [T] represents the standard rail bottom thickness before rust removal, T f Indicates the rail bottom thickness after rust removal.

[0094] Among them, the dynamic calculation results of step 4 are that the rail service performance development prediction model established in step 3 needs to be calculated based on the calculation results of the dynamic model in step 2 as initial conditions. This step sorts out the dynamic calculation results.

[0095] After substituting the specific line and service parameter information in step 1 into the model established in step 2, the main results that need to be calculated and extracted are shown in Table 3:

[0096]

[0097]

[0098] Table 3 Calculation and extraction results

[0099] Wherein, the step 5 of establishing the rail service performance demand model needs to calculate the rail wear resistance, rail contact fatigue damage resistance and rail corrosion resistance parameters, wherein the rail wear resistance needs to be combined with the balance relationship between the natural wear rate of the rail on site and the fatigue damage development rate, to clarify whether the rail wear resistance needs to be improved or reduced, and then calculate the rail profile after wear within an overhaul cycle or a large machine grinding cycle under the conditions of a 10%, 20%, and 30% improvement in wear resistance according to the rail wear development prediction model;

[0100] For high-speed railways, excessive deviation in rail profile after wear will cause reduction in vehicle operating performance, and this is used as the design limit for wear resistance change; for conventional railways, the wear profile retention capability should be improved as much as possible to improve wheel-rail matching and reduce the occurrence of contact fatigue damage. At the same time, the economic benefits of improving / reducing rail wear resistance should also be considered.

[0101] The contact fatigue damage resistance of the rails is generally within 0.2 mm, and the critical damage standard of the crack depth of high-speed rails is 1 mm. The crack growth prediction model is used to calculate the crack growth rate at different initial depths. By improving the contact fatigue damage resistance and reducing the initial crack depth, the crack growth rate extending to a depth of 1 mm is controlled at a stable development stage. The improvement requirements of the contact fatigue damage resistance are calculated according to the following formula:

[0102]

[0103] Where, d i Indicates the acceptable initial contact fatigue damage crack depth,

[0104] For conventional railways, the depth of contact fatigue damage is generally around 1 mm. Therefore, when designing the anti-contact fatigue damage performance, the requirements for improving the anti-contact fatigue damage performance are calculated according to the following formula:

[0105]

[0106] The rail corrosion resistance can be preliminarily estimated based on the thickness of the rail bottom and rail waist after rust removal in the relevant standards. Considering that the rail overhaul cycle is 30 years, the corrosion resistance improvement calculation method is (1-allowable corrosion rate / actual corrosion rate)×100%, and the rail corrosion resistance requirement is calculated:

[0107]

[0108] In the formula, y crepresents the rail corrosion resistance requirement, c f represents the rail bottom corrosion rate, c w represents the rail waist corrosion rate, L represents the service life of the rail, c r Indicates the actual corrosion rate of the rail.

[0109] Among them, the step 6 proposes the demand for improving rail performance according to the calculated and analyzed service performance of each rail, and finally proposes a total rail performance improvement demand plan.

[0110] Example

[0111] Taking a certain high-speed railway as an example, based on the service condition of the rails, the rail performance requirement design method proposed in the present invention is adopted to calculate the rail service performance requirement index and provide a specific improvement / reduction value.

[0112] Step 1: Collect rail service status parameters;

[0113] The type of vehicles running in a certain section of a high-speed railway is a certain series of CRH. The line types include straight lines and curves. The rail material is U71Mn G rail with a profile of 60D. On-site investigation found that there are contact fatigue damage and local rust. Specific information is shown in Table 4 and Table 5:

[0114]

[0115] Table 4 Rail line information of a high-speed railway

[0116]

[0117] Table 5 Service information of rails of a high-speed railway

[0118] Step 2: Establish a simulation analysis model;

[0119] According to the on-site measured rail profile and line parameters, as well as the actual running EMU, the vehicle-track coupling dynamic model is established according to the method in step 2.

[0120] Step 3: prediction of rail service performance development and the results of dynamic calculations in step 4;

[0121] The calculation results required to extract the rail service performance development prediction model are shown in Table 6:

[0122] Parameter name Numeric Parameter name unit Wheel-rail normal stress 600~900MPa Wheel-rail longitudinal creep rate 0～0.001 Wheel-rail tangential stress -150~150MPa Wheel-rail lateral creep rate 0～0.001 Wheel-rail normal force 60~80kN Wheel-rail relative sliding distance 100～1000m Wheel-rail lateral force 0~10kN Wheel-rail relative sliding speed 0~12.5m / s

[0123] Table 6 Calculation results required for the rail service performance development prediction model

[0124] Step 5: Establish rail service performance demand model;

[0125] Based on the dynamic calculation results, they are substituted into the rail service performance development prediction model to calculate the rail service performance development rate.

[0126] (1) Prediction of rail contact fatigue damage development

[0127] According to the distribution range of wheel-rail normal stress during EMU operation, which is basically between 600 and 900 MPa, and the distribution range of tangential stress is basically between -150 and 150 MPa, it can be calculated that Δσ = -166.5 MPa, Δτ = 161 MPa. Since the normal stress direction has no effect on crack propagation, the shear stress is taken and the rail crack propagation rate is calculated as a type II crack.

[0128] According to on-site investigation, considering that the straight or large-radius curve sections of high-speed railway rails have a total weight of 120Mt in service for three years, there is a maximum natural wear of 0.4mm, a rapid grinding amount of 0.1mm and a large machine grinding amount of 0.3mm. The calculated change in the wear depth of the rail head is 0.006mm / Mt.

[0129] According to the contact fatigue damage crack growth rate, considering that the contact fatigue damage depth of high-speed railway EMUs is generally within 0.2mm, in order to control the contact fatigue damage crack growth rate so that it can be kept in a stable development stage as much as possible, combined with the actual situation, considering the crack angle with the fastest growth rate, the initial contact fatigue damage depth should be controlled within the depth range of 0.13mm, which can extend the total weight of the crack expansion to 1mm by 60%, which is conducive to timely detection and arrangement of grinding and treatment. Therefore, the requirements for improving the anti-contact fatigue damage performance of high-speed railway rails are:

[0130]

[0131] (2) Rail wear resistance

[0132] Combining the vehicle-track coupling dynamics model and the Archard wear model, the wear rates under different rail material properties are calculated. The results are shown in Table 7:

[0133]

[0134] Table 7 Wear rate of different rail materials and properties

[0135] When the wear resistance is reduced by 30%, the rail wear will increase rapidly, which will lead to an increase in rail profile deviation and a decrease in wheel-rail matching performance. Therefore, excessive reduction in wear resistance should be avoided. Based on the above analysis, the reduction in wear resistance of high-speed railway rails should be controlled within 20%.

[0136] (3) Rail corrosion resistance

[0137] The rusted rails were derusted and their dimensions were measured. The measurement results show that the rail head width decreased by about 1mm, the rail waist width decreased by about 1.5mm, and the rail bottom width decreased by about 1.7mm. The actual service time of the rails is about 10 years. It can be calculated that the rail waist width narrowing rate caused by rust is about 0.1-0.15mm / year, and the rail bottom thickness reduction rate is about 0.12-0.17m / year.

[0138] According to the high-speed railway line repair regulations, the rust thickness of the rail bottom cannot exceed 4mm (12-8=4mm), and the rust thickness of the rail waist cannot exceed 4.5mm (16.5-12=4.5mm). The rail overhaul cycle is 30 years. Therefore, the corrosion resistance improvement demand of high-speed railway rails can be calculated as:

[0139]

[0140] For this line, the rail corrosion resistance improvement requirement is y c =10%.

[0141] Step 6: Propose requirements for improving rail performance.

[0142] According to the above calculation and analysis, the rail performance requirements of this line are:

[0143] Wear resistance can be reduced by up to 20%, contact fatigue resistance can be increased by 35%, and corrosion resistance needs to be increased by 10%.

[0144] Finally, it should be noted that the above embodiments are only used to describe the technical solution of the present invention rather than to limit the technical method. The present invention can be extended to other modifications, changes, applications and embodiments in application, and therefore it is believed that all such modifications, changes, applications and embodiments are within the spirit and teaching scope of the present invention.

Claims

1. A method for determining rail service performance requirements, characterized in that: The method comprises Step 1: Collect rail service status parameters; Step 2: Establish a simulation analysis model; Step 3: Prediction of rail service performance development; Step 4: Kinetic calculation results; Step 5: Establish rail service performance demand model; Step 6: Propose requirements for improving rail performance.

2. A method for determining rail service performance requirements according to claim 1, characterized in that: The rail service status parameters collected in step 1 include two types: line parameters and rail parameters. The line parameters refer to the type of line (straight line, curve), linear parameters (curve radius, superelevation), operating conditions, and operating vehicle information on which the rail is located; the rail parameters refer to the rail material type, rail profile, smoothness, and damage characteristics, among which smoothness mainly focuses on joint straightness and corrugation, and damage mainly includes contact fatigue-related damage such as abrasions, oblique cracks, fish scales, and rust.

3. The method for determining rail service performance requirements according to claim 1, characterized in that: The simulation analysis model established in step 2 is to establish the dynamic models of conventional trains and high-speed trains respectively according to the different needs of conventional and high-speed railways. The vehicle model is wheelset-bogie-car body from bottom to top. The normal contact between the wheel and the rail is calculated using Hertz elastic contact theory, and the tangential force is calculated using Kalker's simplified algorithm FASTSIM. The suspension system between the wheelset and the frame, and between the frame and the car body are simulated by spatial spring damping force elements. The bogie as a whole is composed of a virtual car body, wheelset, frame, front and rear beams, and the stop force and anti-snaking shock absorber unloading speed take into account their nonlinear characteristics.

4. A method for determining rail service performance requirements according to claim 3, characterized in that: The prediction of the development of rail service performance in step 3 includes prediction of rail wear development, prediction of rail contact fatigue damage crack propagation and prediction of rail corrosion development. The prediction of rail wear development requires the establishment of a rail wear development prediction model. First, the actual line and vehicle parameters on site are input into the vehicle-track coupling dynamics model, and the Archard wear formula is used to calculate the wheel-rail wear. The Archard wear formula is: In the formula, V represents the wear amount, which is the calculation output result. H represents the hardness of the side with higher hardness between the wheel and rail. Other parameters are calculated by the simulation analysis model established in step 2: N represents the normal force of wheel-rail contact, Δs represents the relative sliding distance, k1~k4 represent the wear coefficient, p represents the contact stress, f represents the contact pressure stress limit ratio, v1 and v2 represent the relative sliding speeds of the two boundaries, After setting the wear parameters, the wear calculation can be performed. Each calculation will get the rail wear amount. For the first step of calculation, the wear amount is subtracted from the original rail profile to get the rail profile after wear. The rail profile after wear is substituted into the simulation calculation model and calculated again. And so on, the rail profile under different total weight conditions is obtained. In the prediction of the contact fatigue damage crack growth of the rail, the contact fatigue damage resistance of the rail is mainly reflected in the performance of resisting fatigue crack growth. When predicting the crack growth, the initial shape is considered to be an ellipse. For circular cracks, the critical threshold of crack growth under different wear-resistant rail conditions is first calculated according to the formula, and then the variables are separated and the two sides are integrated to solve the relationship between the crack growth rate and the total weight passing through. The formula is: Where a represents the crack depth, 2c represents the crack width, and d represents the distance between the upper surface of the crack and the top surface of the rail. is the net crack growth rate, w is the rail wear rate under the conditions of rapid grinding and large machine grinding, β is the crack growth angle, is the crack growth rate, which is calculated as: In the formula, C and are material test constants. ΔK eff is the stress intensity factor amplitude, and the calculation formula is: Φ is [1-(a / c) 2 ] is the second kind of elliptic integral, λ represents the geometric effect factor, Δσ represents the stress amplitude, and a represents the crack length; The calculation formula is: In the formula, σ y represents the horizontal shear stress on the rail surface above the crack surface, σ z represents the normal stress in the vertical direction of the rail surface above the crack surface, τ xz represents the shear stress, and the calculation formula is: Where m0 is related to the wheel-rail profile, P represents the wheel-rail vertical force, E represents the rail elastic modulus, r1 represents the arc radius of the vehicle profile, The prediction of rail corrosion development is mainly reflected in that as the service time increases, the thickness of the rail waist and rail bottom is gradually reduced by corrosion. According to the line maintenance rules, the criteria for determining serious damage of rail corrosion mainly include the thickness of the rail bottom and rail waist. Therefore, the development rate of rail corrosion is determined by the change in the thickness of the rail bottom and rail waist before and after rust removal, divided by the actual service life. The formula is: Where, [W] represents the standard rail waist thickness before rust removal, W w represents the rail waist thickness after rust removal, L represents the service life of the rail, [T] represents the standard rail bottom thickness before rust removal, T f Indicates the rail bottom thickness after rust removal.

5. The method for determining rail service performance requirements according to claim 1, characterized in that: The dynamic calculation results of step 4 are that the rail service performance development prediction model established in step 3 needs to be calculated based on the calculation results of the dynamic model in step 2 as initial conditions. This step sorts out the dynamic calculation results.

6. A method for determining rail service performance requirements according to claim 1, characterized in that: The step 5 of establishing the rail service performance demand model requires calculation of rail wear resistance, rail contact fatigue damage resistance and rail corrosion resistance parameters, wherein the rail wear resistance needs to be combined with the balance relationship between the natural wear rate of the rail on site and the fatigue damage development rate, to clarify whether the rail wear resistance needs to be improved or reduced, and then calculate the rail profile after wear within an overhaul cycle or a large machine grinding cycle under the conditions of 10%, 20%, and 30% improvement / reduction in wear resistance according to the rail wear development prediction model; The contact fatigue damage resistance of the rails is generally within 0.2 mm, and the critical damage standard of the crack depth of high-speed rails is 1 mm. The crack growth prediction model is used to calculate the crack growth rate at different initial depths. By improving the contact fatigue damage resistance and reducing the initial crack depth, the crack growth rate extending to a depth of 1 mm is controlled at a stable development stage. The improvement requirements of the contact fatigue damage resistance are calculated according to the following formula: Where, d i Indicates the acceptable initial contact fatigue damage crack depth, For conventional railways, the depth of contact fatigue damage is generally around 1 mm. Therefore, when designing the anti-contact fatigue damage performance, the requirements for improving the anti-contact fatigue damage performance are calculated according to the following formula: The rail corrosion resistance can be preliminarily estimated based on the thickness of the rail bottom and rail waist after rust removal in the relevant standards. Considering that the rail overhaul cycle is 30 years, the corrosion resistance improvement calculation method is (1-allowable corrosion rate / actual corrosion rate)×100%, and the rail corrosion resistance requirement is calculated: In the formula, y c represents the rail corrosion resistance requirement, c f represents the rail bottom corrosion rate, c w represents the rail waist corrosion rate, L represents the service life of the rail, c r Indicates the actual corrosion rate of the rail.

7. A method for determining rail service performance requirements according to claim 1, characterized in that: The step 6 proposes the demand for improving rail performance according to the calculated and analyzed service performance of each rail, and finally proposes a total rail performance improvement demand plan.

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