Wheel-rail material rolling contact fatigue damage prediction method based on different evaluation indices

Abstract

The present invention relates to the technical field of wheel-rail tribology. Specifically disclosed is a wheel-rail material rolling contact fatigue damage prediction method based on different evaluation indices. The method comprises the following steps: on the basis of a wheel-rail shakedown map, carrying out wheel-rail rolling contact fatigue simulation tests, so as to obtain damage states and shakedown limit curve equations of wheel / rail materials with different shear yield strengths under different contact parameters; on the basis of a rough set theory, calculating the importance and relative weights of different evaluation indices; establishing a comprehensive evaluation index cloud model, respectively calculating comprehensive certainty degrees of an index attribute value to be evaluated belonging to different damage states, and using a maximum-value rule for the comprehensive certainty degrees to evaluate and predict rolling contact fatigue damage states; and using comprehensive evaluation index attribute values to perform validation, so as to finally determine a prediction result of a selected wheel-rail material rolling contact fatigue damage state under a condition to be subjected to prediction. The method in the present invention only depends on existing engineering data, such that the subjectivity of a damage state prediction process can be greatly reduced.

Description

Rolling contact fatigue damage prediction method for wheel-rail materials based on different evaluation indicators Technical Field

[0001] The present invention relates to the technical field of wheel-rail tribology, and in particular to a method for predicting rolling contact fatigue damage of wheel-rail materials based on different evaluation indices. Background Art

[0002] With the rapid development of railway transportation, the daily operation and maintenance of wheel-rail systems face new technical challenges. Different wheel-rail systems will show different degrees of rolling contact fatigue damage due to differences in operating conditions and the performance of the wheel-rail materials in service. Various types of wheel-rail rolling contact fatigue damage have become a key issue affecting operational safety and passenger comfort, and will accelerate the degradation of wheel-rail material performance and shorten service life. Solutions to the problem of wheel-rail rolling contact fatigue damage mainly include wheel-rail material optimization and wheel-rail rolling contact friction control strategies. In addition, by evaluating and predicting the rolling contact fatigue damage state of different wheel-rail materials under different contact conditions, it is possible to provide important theoretical guarantees for the safe service of wheels and rails. This allows for the rational selection of wheel-rail materials for complex operating conditions and provides optimized solutions to reduce rolling contact fatigue damage of wheel-rail materials.

[0003] Currently, methods for evaluating and predicting wheel-rail rolling contact fatigue damage primarily rely on the development of engineering-application-oriented computational models, such as the Tγ model and Wedge model, which consider both contact stress and wear, and wheel-rail shakedown diagrams, including fatigue indices, that consider only contact stress. These methods also suffer from empirical judgment in the evaluation and prediction of rolling contact fatigue damage. Furthermore, refined modeling and simulation are conducted, using finite element simulation models combined with the critical plane method for prediction. For example, a three-dimensional wheel-rail transient rolling finite element model calculates the stress-strain field distribution of the rail during a single wheel rollover and combines this with the critical plane method to predict wheel-rail rolling contact fatigue. However, differences in the mechanical properties (shear yield strength) of wheel and rail materials significantly affect wheel-rail rolling contact fatigue damage. Existing engineering computational models and methods rarely consider mechanical properties and introduce material nonlinearity into finite element simulation models, resulting in extremely poor convergence. This further increases the computational complexity and poses a significant challenge to wheel-rail rolling contact fatigue damage prediction.

[0004] Establishing a rolling contact fatigue damage prediction method that simultaneously considers the wheel-rail rolling contact conditions and the mechanical properties of the wheel-rail material, while also being able to use known engineering data to explore the intrinsic relationship between the evaluation indicators and the damage prediction results from objective data, more accurately evaluate and predict the rolling contact fatigue damage of wheel-rail materials with different mechanical properties, further understand the damage state of wheel-rail materials with different mechanical properties under different contact conditions, and provide theoretical support for the formulation of reasonable maintenance strategies for wheel-rail systems. Therefore, it is very necessary to establish a prediction method that can evaluate and predict the rolling contact fatigue damage of wheel-rail materials with different mechanical properties under different contact parameter conditions.

[0005] Summary of the Invention

[0006] To address the deficiencies in the prior art, the present invention provides a method for predicting rolling contact fatigue damage of wheel-rail materials based on different evaluation indicators. This method, starting from the shear yield strength of the wheel-rail material and taking into account the wheel-rail rolling contact parameter conditions, provides a new method for evaluating and predicting rolling contact fatigue damage of wheel-rail materials with different mechanical properties. This method is more objective and universal for evaluating and predicting rolling contact fatigue damage of wheel-rail materials, and solves the problems mentioned in the above-mentioned background technology.

[0007] To achieve the above-mentioned object, the present invention provides the following technical solution: a method for predicting rolling contact fatigue damage of wheel-rail materials based on different evaluation indicators, comprising the following steps:

[0008] S1. Based on the wheel-rail shakedown diagram, conduct wheel-rail rolling contact fatigue simulation tests to obtain the damage states of wheel / rail materials with different shear yield strengths under different contact parameter conditions. At the same time, analyze and obtain the shakedown limit curve equations of the corresponding wheel-rail materials;

[0009] S2. Selecting rolling contact fatigue damage state evaluation indicators based on wheel-rail rolling contact parameters, and calculating the importance and relative weights of different evaluation indicators based on the rolling contact fatigue damage states of wheel / rail materials with different shear yield strengths, i.e., decision attributes, based on rough set mathematical theory;

[0010] S3. Establish a comprehensive evaluation index cloud model to calculate the degree of certainty of attribute values ​​of different comprehensive evaluation indicators belonging to the shakedown and fatigue crack damage states. Then, based on the relative weights of different evaluation indicators in the rolling contact fatigue damage evaluation and the degree of certainty of the comprehensive evaluation indicators, calculate the comprehensive degree of certainty of the attribute values ​​of the evaluated indicators belonging to different damage states, and use the maximum value rule to evaluate and predict the rolling contact fatigue damage state.

[0011] S4. Use the comprehensive evaluation index attribute values ​​to verify the evaluation and prediction results of wheel-rail rolling contact fatigue damage, and finally determine the evaluation and prediction results of the rolling contact fatigue damage state of the selected wheel-rail material under the predicted conditions.

[0012] Preferably, in step S1, a wheel-rail rolling contact fatigue simulation test is carried out based on the wheel-rail stability diagram, specifically including the following:

[0013] The parameters of friction coefficient μ and load factor P0 / k in the wheel-rail classical stability diagram are e As the horizontal and vertical coordinate values ​​in the XY coordinate system, the coordinate points (μ, P0 / k e );

[0014] According to the shear yield strength k of different wheel / rail materials e , the ordinate of the selected coordinate point P0 / k e The value is converted into the normal contact stress P0 during the wheel-rail rolling contact fatigue simulation test. Rolling contact fatigue simulation tests of wheel / rail materials with different shear yield strengths are carried out according to the rolling contact parameters P0 and μ using a laboratory rolling wear and contact fatigue simulation testing machine.

[0015] Preferably, in step S1, the damage states of wheel / rail materials with different shear yield strengths under different contact parameter conditions are obtained, and the shakedown limit curve equations of the corresponding wheel / rail materials are obtained by analysis, which specifically includes the following:

[0016] Microscopic analysis of damaged wheel / rail specimens after rolling contact fatigue simulation tests was performed to observe and distinguish the corresponding damage states under different contact parameter conditions, including no visible damage I, only plastic deformation state (collectively referred to as shakedown II), and rolling contact fatigue crack damage III.

[0017] The actual contact parameters P'0 and μ' of different tests are converted into new coordinate points (μ', P'0 / k e ), according to the difference in damage state of wheel / rail materials with different shear yield strength, the corresponding new coordinate points are fitted by the nonlinear fitting method in the process of classic shakedown diagram construction to construct the shakedown limit curves of wheel / rail materials with different shear yield strength and the corresponding curve equation P0 / k e =A×μ -t , that is, P0 / k e as a function of μ, where A and t are constants.

[0018] Preferably, in step S2, rolling contact fatigue damage evaluation indicators are selected according to the wheel-rail rolling contact parameters, and the importance and relative weights of different evaluation indicators are calculated based on rough set mathematical theory according to the rolling contact fatigue damage states of different wheel / rail materials, specifically including the following:

[0019] First, the shear yield strength k of the wheel / rail material ise Denoted as c1, load factor P0 / k e Recorded as c2, friction coefficient μ recorded as c3 and comprehensive evaluation index P0 / k e ×μ t Denoted as c4, as four evaluation indicators of rolling contact fatigue damage status;

[0020] Secondly, different groups of test parameters and corresponding damage states are selected as sample data. Through the rough set mathematical theory, there is a decision system S = (U, C∪D, V, f), where U is the object set, C is the conditional attribute, that is, the evaluation index, D is the decision attribute, V is the attribute value range, and f is an attribute value assigned to the attribute of each object. At the same time, the initial decision table is obtained according to the different evaluation index attribute values ​​in the sample data and the corresponding rolling contact fatigue damage results, and the discrimination matrix M is listed according to the discrimination conditions. nxn ,Right now:

[0021] Among them, m ij To distinguish the elements in the matrix, i∈(1,n),j∈(1,n);

[0022] and,

[0023] Then, the importance of different evaluation indicators is calculated by distinguishing the matrix Right now:

[0024] Where a∈C, K is the discriminative matrix M nxn The number of non-empty elements in the set, c ij (a) represents the proportion of different evaluation indicators, and where |m ij | represents a non-empty element m ij The number of a conditional attribute contained in ;

[0025] Finally, in the decision system S, based on the importance of different evaluation indicators, their relative weights ω(c i ) is expressed as:

[0026] in, Indicates the importance of different evaluation indicators.

[0027] Preferably, in step S3, a comprehensive evaluation index P0 / k is established e ×μ t The cloud model calculates the degree of certainty of the attribute values ​​of different comprehensive evaluation indicators belonging to the shakedown and fatigue crack damage states, including the following:

[0028] According to the shakedown limit curves of wheel / rail materials with different shear yield strengths and the corresponding curve equations, i.e. P0 / k e As a function of μ, the comprehensive evaluation index P0 / k of wheel / rail materials with different shear yield strength is calculated respectively. e ×μ t For different damage state ranges (r ij ,r' ij ) Digital characteristic values ​​of the cloud model:

[0029] Among them, Ex(ij) and En(ij) are the digital eigenvalue expectation and digital eigenvalue entropy of the cloud model respectively, (r ij ,r' ij ) represents the range of damage status;

[0030] Then, the comprehensive evaluation index P0 / k is obtained e ×μ t Average values ​​of numerical eigenvalues ​​of the cloud model for the range of shakedown and fatigue crack damage states and For any sample x* to be evaluated, calculate its comprehensive evaluation index attribute value c i *Degree of certainty U belonging to shakedown and fatigue crack damage states j for:

[0031] Among them, μ ij Represents the degree of certainty calculated in the cloud model, m is an integer greater than 1, ω(c i ) represents the relative weights of different evaluation indicators.

[0032] Preferably, in step S3, the relative weights of different evaluation indicators in the rolling contact fatigue damage evaluation and the certainty of the comprehensive evaluation indicators are used to calculate the comprehensive certainty of the attribute values ​​of the evaluation indicators belonging to different damage states, and the rolling contact fatigue damage state is evaluated and predicted using the maximum value rule, which specifically includes the following:

[0033] Comprehensive certainty W j The calculation method is:

[0034] W j =ω(c1)×k e +ω(c2)×P0 / k e +ω(c3)×μ+U j

[0035] Where ω(c1) represents the shear yield strength value k of the material e The relative weight of ω(c2) represents the load factor P0 / ke The relative weight of ω(c3) represents the relative weight of the friction coefficient μ, U j Represents the comprehensive evaluation index attribute value c of the sample to be evaluated x* i *Degree of certainty pertaining to shakedown and fatigue crack damage states;

[0036] Calculate W separately 安定 and W 裂纹 , if W 安定 >W 裂纹 , then the damage type under the condition of the attribute value of the index to be evaluated is judged to be a stable state; otherwise, the damage type is judged to be a fatigue crack damage state.

[0037] Preferably, in step S4, the comprehensive evaluation index P0 / k e ×μ t To verify the damage evaluation and prediction results of the wheel-rail material under the predicted conditions, and finally determine the evaluation and prediction results of the rolling contact fatigue damage state of the selected material under the predicted conditions, specifically including the following:

[0038] For wheel / rail materials with different shear yield strengths, the shakedown limit curve equation for wheel / rail materials with different shear yield strengths is obtained according to the method proposed in the wheel-rail rolling contact fatigue simulation test. e =A×μ -t , and then calculate the comprehensive evaluation index attribute P0 / k of the attribute value of the index to be evaluated e ×μ t The value A' is compared with the size of A in the curve equation to further verify the damage evaluation and prediction results of step S3, and finally determine the evaluation and prediction results of the rolling contact fatigue damage state of the selected material under the conditions to be predicted.

[0039] The present invention has the following beneficial effects: The method for predicting rolling contact fatigue damage states of wheel-rail materials, utilizing rough set mathematical theory and a cloud model, relies solely on existing engineering data, significantly reducing subjectivity in the damage state prediction process. Starting from the shear yield strength of the wheel-rail material and simultaneously considering wheel-rail rolling contact parameters, the present invention provides a new method for evaluating and predicting rolling contact fatigue damage in wheel-rail materials with different mechanical properties. This method provides a more objective and universal method for evaluating and predicting rolling contact fatigue damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] FIG1 is a schematic flow chart of the steps of the method of the present invention. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0042] Referring to FIG1 , the present invention provides a technical solution: a method for predicting rolling contact fatigue damage of wheel-rail materials based on different evaluation indicators. The process is shown in FIG1 , and includes the following steps:

[0043] S1. Based on the wheel-rail shakedown diagram, a wheel-rail rolling contact fatigue simulation test was conducted to obtain the damage state of rail materials with different shear yield strengths under different contact parameter conditions. At the same time, the shakedown limit curve equation of the corresponding rail material was analyzed and obtained.

[0044] Furthermore, based on the wheel-rail stability diagram, a wheel-rail rolling contact fatigue simulation test was carried out, specifically including the following:

[0045] The parameters of friction coefficient μ and load factor P0 / k in the wheel-rail classical stability diagram are e As the horizontal and vertical coordinate values ​​in the XY coordinate system, the coordinate points (μ, P0 / k e );

[0046] According to the shear yield strength k of different rail materials e , the ordinate of the selected coordinate point P0 / k e The value is converted into the normal contact stress P0 during the wheel-rail rolling contact fatigue simulation test. Rolling contact fatigue simulation tests of rail materials with different shear yield strengths are carried out according to the rolling contact parameters P0 and μ using a laboratory rolling wear and contact fatigue simulation testing machine.

[0047] Furthermore, the damage states of rail materials with different shear yield strengths under different contact parameter conditions were obtained, and the shakedown limit curve equations of the corresponding rail materials were obtained by analysis, including the following:

[0048] Microscopic analysis of damaged rail specimens after rolling contact fatigue simulation tests was conducted to observe and distinguish the corresponding damage states under different contact parameter conditions, including no visible damage I and only plastic deformation state (collectively referred to as stability II), and rolling contact fatigue crack damage III.

[0049] The actual contact parameters P'0 and μ' of different tests are converted into new coordinate points (μ', P'0 / k e), according to the difference in damage state of rail materials with different shear yield strength, the corresponding new coordinate points are fitted by the nonlinear fitting method in the process of classic shakedown diagram construction to obtain the shakedown limit curves of rail materials with different shear yield strength and the corresponding curve equation P0 / k e =A×μ -t , that is, P0 / k e as a function of μ;

[0050] Where A and t are constants, according to different shear yield strength values ​​k e The changing law of the shakedown limit curve equation of rail material is as follows: A=-0.00345k e +1.842, t=5.284×10 -6 k e 2.035 Perform calculations.

[0051] Furthermore, wheel-rail rolling contact fatigue simulation tests were carried out, and sample data of rail material test results were selected as shown in Table 1.

[0052] Table 1 Damage results of rolling contact fatigue simulation tests on rail materials under different contact conditions

[0053] At the same time, different shear yield strengths (k e ) Shakedown limit curve equation of rail material P0 / k e =A×μ -t , that is, P0 / k e As a function of μ (where A and t are constants), the specific equation is:

[0054] k e1 =270.2MPa:p0 / k e =0.89μ -0.56

[0055] k e2 =374.1MPa:p0 / k e =0.59μ -0.82

[0056] k e3 =490.2MPa:p0 / k e =0.12μ -1.57

[0057] k e4 =513.8MPa:p0 / k e =0.08μ -1.77

[0058] S2. Selecting rolling contact fatigue damage state evaluation indicators based on the wheel-rail rolling contact parameters, including proposing comprehensive evaluation indicators and calculating the importance and relative weights of different evaluation indicators based on the rolling contact fatigue damage states of rail materials with different shear yield strengths, i.e., decision attributes, based on rough set mathematical theory; specifically, including the following:

[0059] First, the shear yield strength k of the material e Denoted as c1, load factor P0 / k e Recorded as c2, friction coefficient μ recorded as c3 and comprehensive evaluation index P0 / k e ×μ t Denoted as c4, as four evaluation indicators of rolling contact fatigue damage status;

[0060] Secondly, different groups of test parameters and corresponding damage states are selected as sample data. Through the rough set mathematical theory, there is a decision system S = (U, C∪D, V, f), where U is the object set, C is the conditional attribute, that is, the evaluation index, D is the decision attribute, V is the attribute value range, and f is an attribute value assigned to the attribute of each object.

[0061] According to the rolling contact fatigue damage states of rail materials with different shear yield strengths, the selected test result sample data are simplified into an initial decision table in the rough set mathematical theory through four different evaluation indicators, as shown in Table 2.

[0062] Table 2 Initial decision table

[0063] According to the rough set mathematical theory, through the initial decision table, according to the distinction conditions

[0064] List the discriminability matrix M nxn ,Right now:

[0065] Among them, m ij To distinguish the elements in the matrix, i∈(1,n),j∈(1,n);

[0066] The discrimination matrix is ​​specifically:

[0067] Then, the importance of different evaluation indicators is calculated by distinguishing the matrix Right now:

[0068] Where a∈C, K is the discriminative matrix M nxn The number of non-empty elements in the set, c ij (a) represents the proportion of different evaluation indicators, and where |mij | represents a non-empty element m ij The number of a conditional attribute contained in ;

[0069] The specific calculation results are:

[0070] Finally, in the decision system S, based on the importance of different evaluation indicators, their relative weights ω(c i ) is expressed as:

[0071] in, Indicates the importance of different evaluation indicators.

[0072] The specific calculation results are:

[0073] ω(c1)=0.28

[0074] ω(c2)=0.26

[0075] ω(c3)=0.18

[0076] ω(c4)=0.28

[0077] S3. Establish a comprehensive evaluation index cloud model to calculate the degree of certainty of attribute values ​​of different comprehensive evaluation indicators belonging to the shakedown and fatigue crack damage states. Then, based on the relative weights of different evaluation indicators in the rolling contact fatigue damage evaluation and the degree of certainty of the comprehensive evaluation indicators, calculate the comprehensive degree of certainty of the attribute values ​​of the evaluated indicators belonging to different damage states, and use the maximum value rule to evaluate and predict the rolling contact fatigue damage state.

[0078] Furthermore, a comprehensive evaluation index P0 / k is established e ×μ t The cloud model calculates the degree of certainty of the attribute values ​​of different comprehensive evaluation indicators belonging to the shakedown and fatigue crack damage states, including the following:

[0079] According to the shakedown limit curves of rail materials with different shear yield strengths and the corresponding curve equations, namely P0 / k e As a function of μ, the comprehensive evaluation index P0 / k of rail materials with different shear yield strength is calculated respectively. e ×μ t For different damage state ranges (r ij ,r' ij ) Digital characteristic values ​​of the cloud model:

[0080] Among them, Ex(ij) and En(ij) are the digital eigenvalue expectation and digital eigenvalue entropy of the cloud model respectively, (r ij ,r' ij ) represents the damage status range.

[0081] Then, the comprehensive evaluation index P0 / k is obtained e ×μ t Average values ​​of numerical eigenvalues ​​of the cloud model for the range of shakedown and fatigue crack damage states and The specific results are shown in Table 3.

[0082] Table 3 Specific results of comprehensive evaluation index for the cloud model of shakedown and fatigue crack damage state range

[0083] Ex' and En' represent the expected eigenvalue and entropy of the cloud model under fatigue crack damage state, respectively, which correspond to the expected eigenvalue Ex and entropy En of the cloud model under stable state.

[0084] For any sample x* to be evaluated, calculate its comprehensive evaluation index attribute value c i *Degree of certainty U belonging to shakedown and fatigue crack damage states j for:

[0085] Among them, μ ij Represents the degree of certainty calculated in the cloud model, m is an integer greater than 1, ω(c i ) represents the relative weights of different evaluation indicators.

[0086] Furthermore, based on the relative weights of different evaluation indicators in rolling contact fatigue damage evaluation and the certainty of the comprehensive evaluation indicators, the comprehensive certainty of the attribute values ​​of the evaluated indicators belonging to different damage states is calculated respectively, and the rolling contact fatigue damage state is evaluated and predicted based on the maximum value rule, specifically including the following:

[0087] Comprehensive certainty W j The calculation method is:

[0088] W j =ω(c1)×k e +ω(c2)×P0 / k e +ω(c3)×μ+U j

[0089] Where ω(c1) represents the shear yield strength value k of the material e The relative weight of ω(c2) represents the load factor P0 / k eThe relative weight of ω(c3) represents the relative weight of the friction coefficient μ, U j Represents the comprehensive evaluation index attribute value c of the sample to be evaluated x* i *Degree of certainty pertaining to shakedown and fatigue crack damage states;

[0090] Calculate W separately 安定 and W 裂纹 , if W 安定 >W 裂纹 , then the damage type under the condition of the attribute value of the index to be evaluated is judged to be a stable state; otherwise, the damage type is judged to be a fatigue crack damage state.

[0091] S4. Use the comprehensive evaluation index attribute values ​​to verify the evaluation and prediction results of wheel-rail rolling contact fatigue damage, and finally determine the evaluation and prediction results of the rolling contact fatigue damage state of the selected material under the predicted conditions.

[0092] Furthermore, the comprehensive evaluation index P0 / k e ×μ t To verify the damage evaluation and prediction results of the rail material under the predicted conditions, and finally determine the evaluation and prediction results of the rolling contact fatigue damage state of the selected material under the predicted conditions, specifically including the following:

[0093] For rail materials with different shear yield strengths, the shakedown limit curve equation for wheel-rail materials with different shear yield strengths is obtained according to the method proposed in the wheel-rail rolling contact fatigue simulation test. e =A×μ -t , and then calculate the comprehensive evaluation index attribute P0 / k of the attribute value of the index to be evaluated e ×μ t The value A' is compared with the size of A in the curve equation to further verify the damage evaluation and prediction results of step S3, and finally determine the evaluation and prediction results of the rolling contact fatigue damage state of the selected material under the conditions to be predicted.

[0094] The following is an experimental verification of several sample data to be tested using the technical solution of the present invention:

[0095] Verification Example 1

[0096] Sample data to be predicted 1: k e =513.8MPa(U78CrV), P0 / k e =1.5, μ=0.29, P0 / k e ×μ t =0.16770

[0097] W1=ω(c1)×k e+ω(c2)×P0 / k e +ω(c3)×μ+U s =143.86+0.39+0.05+0.28=144.59

[0098] W2=ω(c1)×k e +ω(c2)×P0 / k e +ω(c3)×μ+U c =143.86+0.39+0.05+0.35=144.66

[0099] Since W2>W1, the damage state under this condition is fatigue crack, U s and U c are the certainty values ​​of the measured values ​​of the comprehensive evaluation index belonging to the shakedown and fatigue crack damage states, respectively.

[0100] At the same time k e =513.8MPa, we can know its shakedown limit curve equation: p0 / k e =0.08μ -1.77

[0101] The comprehensive evaluation index value P0 / k of this sample data e ×μ t =0.16770>0.08, and the damage state under this condition is finally judged to be fatigue crack damage, which is consistent with the test results.

[0102] Verification Example 2:

[0103] Sample data to be predicted 2: k e =270.2MPa(U71Mn), P0 / k e =2.0, μ=0.20, P0 / k e ×μ t =0.81209

[0104] W1=ω(c1)×k e +ω(c2)×P0 / k e +ω(c3)×μ+U s =75.66+0.52+0.04+0.28=76.49

[0105] W2=ω(c1)×k e +ω(c2)×P0 / k e +ω(c3)×μ+U c =75.66+0.52+0.04+0.30=76.51

[0106] Since W2>W1, the damage state under this condition is judged to be fatigue crack.

[0107] At the same time k e =270.2MPa, we can know its shakedown limit curve equation: p0 / k e =0.89μ -0.56

[0108] The comprehensive evaluation index value P0 / k of this sample data e ×μ t =0.81209<0.89, ultimately judging the damage state under this condition to be stable, which is consistent with the experimental results. (This also indicates that the prediction results based solely on rough set theory are slightly safer.)

[0109] Verification Example 3:

[0110] Sample data to be predicted 3: k e =513.8MPa(U78CrV), P0 / k e =2.5, μ=0.2, P0 / k e ×μ t =0.14480

[0111] W1=ω(c1)×k e +ω(c2)×P0 / k e +ω(c3)×μ+U s =143.86+0.65+0.04+0.28=144.83

[0112] W2=ω(c1)×k e +ω(c2)×P0 / k e +ω(c3)×μ+U c =143.86+0.65+0.04+0.35=144.90

[0113] Since W2>W1, the damage state under this condition is judged to be fatigue crack.

[0114] At the same time k e =513.8MPa, we can know its shakedown limit curve equation: p0 / k e =0.08μ -1.77

[0115] The comprehensive evaluation index value P0 / k of this sample data e ×μ t =0.14480>0.08, and the damage state under this condition is finally judged to be fatigue crack damage, which is within the range of the corresponding shakedown limit of this rail material.

[0116] The wheel-rail rolling contact fatigue damage prediction method of the present invention, which utilizes rough set mathematical theory and cloud model, only relies on existing engineering data and can greatly reduce the subjectivity of the damage state prediction process.

[0117] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for predicting rolling contact fatigue damage of wheel-rail materials based on different evaluation indicators, characterized in that: The steps include: S1. Based on the wheel-rail shakedown diagram, conduct wheel-rail rolling contact fatigue simulation tests to obtain the damage states of wheel / rail materials with different shear yield strengths under different contact parameter conditions. At the same time, analyze and obtain the shakedown limit curve equations of the corresponding wheel / rail materials; S2. Selecting rolling contact fatigue damage state evaluation indicators based on wheel-rail rolling contact parameters, and calculating the importance and relative weights of different evaluation indicators based on the rolling contact fatigue damage states of wheel / rail materials with different shear yield strengths, i.e., decision attributes, based on rough set mathematical theory; S3. Establish a comprehensive evaluation index cloud model to calculate the degree of certainty of attribute values ​​of different comprehensive evaluation indicators belonging to the shakedown and fatigue crack damage states. Then, based on the relative weights of different evaluation indicators in the rolling contact fatigue damage evaluation and the degree of certainty of the comprehensive evaluation indicators, calculate the comprehensive degree of certainty of the attribute values ​​of the evaluated indicators belonging to different damage states, and use the maximum value rule to evaluate and predict the rolling contact fatigue damage state. S4. Verify the evaluation and prediction results of wheel-rail rolling contact fatigue damage using the comprehensive evaluation index attribute values, and ultimately determine the evaluation and prediction results of the rolling contact fatigue damage state of the selected wheel-rail material under the predicted conditions; In step S2, rolling contact fatigue damage evaluation indicators are selected according to the wheel-rail rolling contact parameters, and the importance and relative weights of different evaluation indicators are calculated based on the rough set mathematical theory according to the rolling contact fatigue damage states of different wheel / rail materials, specifically including the following: First, the shear yield strength k of the wheel / rail material is e Denoted as c1, load factor P0 / k e Recorded as c2, friction coefficient μ recorded as c3 and comprehensive evaluation index P0 / k e ×μ t Denoted as c4, as four evaluation indicators of rolling contact fatigue damage status; Secondly, different groups of test parameters and corresponding damage states are selected as sample data, and the rough set Mathematical theory, in which there is a decision system S = (U, C∪D, V, f), where U is the object set, C is the condition attribute, that is, the evaluation index, D is the decision attribute, V is the attribute value range, and f is an attribute value assigned to the attribute of each object. At the same time, the initial decision table is obtained according to the different evaluation index attribute values ​​in the sample data and the corresponding rolling contact fatigue damage results, and the discrimination matrix M is listed according to the discrimination conditions. nxn ,Right now: Among them, m ij To distinguish the elements in the matrix, i∈(1,n),j∈(1,n); and, Then, the importance of different evaluation indicators is calculated by distinguishing the matrix Right now: Where a∈C, K is the discriminative matrix M nxn The number of non-empty elements in the set, c ij (a) represents the proportion of different evaluation indicators, and where |m ij | represents a non-empty element m ij The number of a conditional attribute contained in ; Finally, in the decision system S, based on the importance of different evaluation indicators, their relative weights ω(c i ) is expressed as: in, Indicates the importance of different evaluation indicators; In step S3, a comprehensive evaluation index P0 / k is established e ×μ t The cloud model calculates the degree of certainty of the attribute values ​​of different comprehensive evaluation indicators belonging to the shakedown and fatigue crack damage states, including the following: According to the shakedown limit curves of wheel / rail materials with different shear yield strengths and the corresponding curve equations, i.e. P0 / k e As a function of μ, the comprehensive evaluation index of wheel / rail materials with different shear yield strength is calculated respectively. P0 / k e ×μ t For different damage state ranges (r ij ,r' ij ) Digital characteristic values ​​of the cloud model: Among them, Ex(ij) and En(ij) are the digital eigenvalue expectation and digital eigenvalue entropy of the cloud model respectively, (r ij ,r' ij ) represents the range of damage status; Then, the comprehensive evaluation index P0 / k is obtained e ×μ t Average values ​​of numerical eigenvalues ​​of the cloud model for the range of shakedown and fatigue crack damage states and For any sample x* to be evaluated, calculate its comprehensive evaluation index attribute value c i *Degree of certainty U belonging to shakedown and fatigue crack damage states j for: Among them, μ ij Represents the degree of certainty calculated in the cloud model, m is an integer greater than 1, ω(c i ) represents the relative weights of different evaluation indicators; In step S3, the relative weights of different evaluation indicators in the rolling contact fatigue damage evaluation and the certainty of the comprehensive evaluation indicators are used to calculate the comprehensive certainty of the attribute values ​​of the evaluation indicators belonging to different damage states, and the rolling contact fatigue damage state is evaluated and predicted using the maximum value rule, which specifically includes the following: Comprehensive certainty W j The calculation method is: IN j =ω(c1)×k e +ω(c2)×P0 / k e +ω(c3)×μ+U j Where ω(c1) represents the shear yield strength value k of the material e The relative weight of ω(c2) represents the load factor P0 / k e The relative weight of ω(c3) represents the relative weight of the friction coefficient μ, U j Represents the comprehensive evaluation index attribute value c of the sample to be evaluated x* i *Degree of certainty pertaining to shakedown and fatigue crack damage states; Calculate W separately 安定 and W 裂纹 , if W 安定 >W 裂纹 , then determine the attribute value condition of the indicator to be evaluated The damage type under this condition is stable state; otherwise, the damage type is fatigue crack damage state; In step S4, the comprehensive evaluation index P0 / k e ×μ t To verify the damage evaluation and prediction results of the wheel-rail material under the predicted conditions, and finally determine the evaluation and prediction results of the rolling contact fatigue damage state of the selected material under the predicted conditions, specifically including the following: For wheel / rail materials with different shear yield strengths, the shakedown limit curve equation for wheel / rail materials with different shear yield strengths is obtained according to the method proposed in the wheel-rail rolling contact fatigue simulation test. e =A×μ -t , and then calculate the comprehensive evaluation index attribute P0 / k of the attribute value of the index to be evaluated e ×μ t The value A' is calculated and compared with the value A in the curve equation to further verify the damage evaluation and prediction results of step S3, and finally determine the evaluation and prediction results of the rolling contact fatigue damage state of the selected wheel-rail material under the predicted conditions.

2. The method for predicting rolling contact fatigue damage of wheel-rail materials based on different evaluation indicators according to claim 1, characterized in that: In step S1, a wheel-rail rolling contact fatigue simulation test is carried out based on the wheel-rail stability diagram, specifically including the following: The parameters of friction coefficient μ and load factor P0 / k in the wheel-rail classical stability diagram are e As the horizontal and vertical coordinate values ​​in the XY coordinate system, the coordinate points (μ, P0 / k e ); According to the shear yield strength k of different wheel / rail materials e , the ordinate of the selected coordinate point P0 / k e The value is converted into the normal contact stress P0 during the wheel-rail rolling contact fatigue simulation test. Rolling contact fatigue simulation tests of wheel / rail materials with different shear yield strengths are carried out according to the rolling contact parameters P0 and μ using a laboratory rolling wear and contact fatigue simulation testing machine.

3. The method for predicting rolling contact fatigue damage of wheel-rail materials based on different evaluation indicators according to claim 1, characterized in that: In step S1, the damage states of wheel / rail materials with different shear yield strengths under different contact parameter conditions are obtained, and the shakedown limit curve equations of the corresponding wheel / rail materials are obtained by analysis, which specifically include the following: Microscopic analysis of damaged wheel / rail specimens after rolling contact fatigue simulation tests was performed to observe and distinguish the corresponding damage states under different contact parameter conditions, including no visible damage I, only plastic deformation state (collectively referred to as stability II), and rolling contact fatigue crack damage III. The actual contact parameters P'0 and μ' of different tests are converted into new coordinate points (μ', P'0 / k e ), according to the difference in damage state of wheel / rail materials with different shear yield strength, the corresponding new coordinate points are fitted by the nonlinear fitting method in the process of classic shakedown diagram construction to obtain the shakedown limit curves of wheel / rail materials with different shear yield strength and the corresponding curve equation P0 / k e =A×μ -t , that is, P0 / k e as a function of μ, where A and t are constants.

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