Thermal coupling analysis method for pantograph-catenary system of railway vehicle

Abstract

The invention discloses a thermal coupling analysis method for a pantograph-catenary system of a railway vehicle, which belongs to the field of contact analysis of the pantograph-catenary system of the railway vehicle and comprises the following steps of: establishing a three-dimensional model of a pantograph carbon contact strip; according to the geometrical characteristics of the pantograph carbon contact strip, grid division is carried out on the three-dimensional model of the pantograph carbon contact strip, and a thermal coupling finite element model is obtained; analyzing the contact thermal boundary of the pantograph-catenary system; according to the contact thermal boundary analysis result of the pantograph-catenary system, a heat source is analyzed when the rail vehicle runs and is subjected to dynamic current collection; and setting an iteration step length and an iteration step number, setting an environment temperature boundary condition, solving the thermal coupling model of the pantograph carbon contact strip, and obtaining a thermal coupling analysis result. The method has the advantages of being high in calculation efficiency, short in needed time, not limited by conditions such as test sites and cost and the like, accurate and rapid prediction of the pantograph-catenary contact temperature and stress is achieved, and guidance is provided for accurate and reasonable evaluation of optimization design and analysis of the railway vehicle pantograph-catenary system.

Description

Technical Field

[0001] The present invention relates to the field of contact analysis of a railway vehicle pantograph-catenary system, and in particular to a thermal-mechanical coupling analysis method of a railway vehicle pantograph-catenary system. Background Art

[0002] The pantograph-catenary system is one of the important subsystems of the high-speed train coupling system, in which the pantograph carbon plate is a key current-collecting component, and its current-collecting quality is affected by many factors such as mechanics, machinery, electricity and materials. The traditional pantograph-catenary system interaction analysis method mainly focuses on simple dynamic analysis or thermal analysis, ignoring the influence of temperature and mechanical stress coupling.

[0003] At present, from the literature at home and abroad, there is no research and application on the thermal coupling analysis of the pantograph-catenary system. Some scholars at home and abroad have deeply analyzed the sliding electrical contact behavior from the perspective of energy dissipation and conversion, and explored the influence of different parameters such as contact current and running speed on the temperature field through theoretical calculation and simulation analysis. Some scholars at home and abroad have also studied the pantograph-catenary contact problem during train operation through dynamic methods.

[0004] In fact, when the pantograph is working, it is not only subjected to the dynamic contact pressure of the contact network, but also generates friction heat and current heat due to electrical contact. The heat source of the pantograph-network contact is mobile due to the existence of the pull-out value. The mobile heat source causes the unevenly distributed temperature increment on the surface of the pantograph carbon slide plate. The unevenly distributed temperature increment will lead to the uneven distribution of local stress and deformation, as well as local thermal shock and thermal damage. The thermal-mechanical coupling analysis method can accurately reflect the interaction between temperature and structural deformation, and realize the accurate simulation analysis of the current collection of the pantograph-network system. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a thermal-mechanical coupling analysis method for a rail vehicle pantograph-catenary system, which realizes accurate and rapid prediction of pantograph-catenary contact temperature and stress.

[0006] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0007] This solution provides a method for thermal-mechanical coupling analysis of a rail vehicle pantograph-catenary system, including:

[0008] S1. Construct a three-dimensional model of the pantograph carbon slide plate;

[0009] S2. According to the geometric characteristics of the pantograph carbon slide plate, the pantograph carbon slide plate three-dimensional model is meshed to obtain a thermal-mechanical coupling finite element model;

[0010] S3. Based on the thermal-mechanical coupling finite element model, the mesh type is assigned and divided, and three types of boundary conditions of the thermal-mechanical coupling finite element model are obtained through calculation; wherein the three types of boundary conditions include heat flux density boundary conditions, convection heat transfer boundary conditions and radiation boundary conditions;

[0011] S4. Analyze the heat source of the rail vehicle during operation according to the three types of boundary conditions to obtain the heat source analysis results;

[0012] S5. Based on the heat source analysis results, the heat flux per unit area is calculated by heat flux density. Combined with the temperature distribution at the initial moment and three types of boundary conditions, the iteration step size and number of iteration steps are set to solve the solution of the pantograph non-steady-state heat conduction at each moment and obtain the thermal-mechanical coupling analysis results.

[0013] Beneficial effects of the present invention: The present invention conducts thermal and structural analysis on the pantograph under the dynamic current environment of the train, covering heat conduction, heat convection and heat radiation, taking into account three heat sources: current heat, friction heat and convection heat transfer, and obtains the results of the temperature, deformation, strain and stress distribution of the pantograph carbon slide in the thermal environment, which more detailedly and truly reflects the thermal damage law of the pantograph carbon slide under the temperature shock load, the hot spots on the surface of the carbon strip of the pantograph carbon slide and the main occurrence area of ​​elastic warping deformation of the pantograph carbon slide. The calculation results can provide theoretical reference for the thermal safety optimization design and fatigue life analysis of the pantograph-net system.

[0014] Furthermore, the specific steps of S3 are as follows:

[0015] S301. Calculate the effect of heat conduction on the contact thermal boundary of the pantograph-catenary system:

[0016]

[0017] In the formula, Q c is the heat flow of heat conduction, k is the thermal conductivity, A is the area of ​​heat conduction, and dT / dx is the temperature gradient.

[0018] S302. Calculate the influence of thermal convection on the contact thermal boundary of the pantograph-catenary system:

[0019] Q d =αS(T f -T W )

[0020] Among them, the upper surface is a heat transfer mode of fluid sweeping the flat plate, and the convection heat transfer coefficient is expressed as:

[0021]

[0022] The front surface is a heat transfer mode in which the fluid sweeps across the column, and the convection heat transfer coefficient is expressed as:

[0023]

[0024] The heat transfer mode of the rear surface is natural convection heat transfer, and the convection heat transfer coefficient is expressed as:

[0025]

[0026] In the formula, Q d is the convective heat transfer energy, α is the convective heat transfer coefficient, S is the convective heat transfer area, T f is the temperature of the fluid, w is the temperature of the pantograph carbon slide surface, b is the width of the slide; u is the air velocity, which is equivalent to the train running speed here; Pr is called Prandtl constant; v is the kinematic viscosity of air; α is the thermal diffusivity of air; g is the gravitational acceleration; Δt is the difference between the surface temperature and the ambient temperature; C is the Grashof number correlation coefficient; l is the convection surface length; α v is the volume expansion coefficient, calculated using the inverse of the average temperature of the fluid in the boundary layer; n is the empirical coefficient; λ is the thermal conductivity of air; the values ​​of λ, v, and a are related to temperature;

[0027] S303. Calculate the influence of thermal radiation on the contact thermal boundary of the pantograph-catenary system:

[0028]

[0029] σ=5.677×10 -8 W / (m 2 ·k 4 )

[0030] In the formula, Q r is the energy generated by thermal radiation, T α is the atmospheric temperature; s is the surface temperature of the object; ε is the surface blackness coefficient, the surface blackness coefficient range of the aluminum bracket and the horn is 0.05-0.15, and the surface blackness coefficient of the skateboard is 0.9-0.95; σ is the Stefan-Boltzmann constant.

[0031] The beneficial effect of the above further scheme is that by calculating the influence of heat conduction, heat convection and heat radiation on the contact thermal boundary of the pantograph-catenary system, the heat exchange process between the pantograph carbon slide plate and the contact network under actual operating conditions can be more accurately simulated. By analyzing the thermal boundary conditions, the thermal behavior of the pantograph carbon slide plate during operation can be better understood, thereby predicting possible thermal faults or thermal failures.

[0032] Furthermore, the expression of the S4 heat source Q is:

[0033]

[0034] Among them, according to the current thermal power and contact resistance, the current thermal Q is obtained I The expression is:

[0035] P I =(1-η)I 2 R c

[0036]

[0037]

[0038] Friction heat Q f The expression is:

[0039]

[0040] According to the results of the contact thermal boundary analysis of the pantograph-catenary system, the temperature rise change Q is obtained. other The expression is:

[0041] Q other =Q c +Q r +Q d

[0042] In the formula, Q is the heat source, q i is the heat flux density, A is the nominal contact area between the friction pairs, τ is the time, P I is the current thermal power, R C is the contact resistance, I is the current, is the offline rate, ρ is the density, a, b, c, d, m, n, p, q are all unknown parameters, H is the hardness of the softer material, the unit is N·m -2 , E is the equivalent elastic modulus, the unit is Pa, V is the running speed of the rail vehicle, F, I, v are all variables, the units are N, A and km / h respectively, t is the running time of the rail vehicle, μ c is the Coulomb friction coefficient, μ s is the maximum friction coefficient, σ is the viscosity effect, ΔF is the pressure fluctuation amplitude, a1, a2, a3, b1, b3, d, v s are all fitted correlation coefficients, and z is an undetermined coefficient.

[0043] The beneficial effect of the above further scheme is that the heat source Q is decomposed into current heat, friction heat and other heat sources (such as temperature rise change Q caused by factors such as convection). other ), which can more comprehensively consider various heat source conditions that the pantograph-catenary system may encounter during actual operation, and help to more accurately evaluate the thermal-mechanical coupling characteristics of the pantograph carbon slide plate.

[0044] Furthermore, the specific steps of S5 are as follows:

[0045] S501. Determine the speed V0 of the moving heat source:

[0046]

[0047] Where l1 is the pull-out value, θ is the angle between the pull-out value and the span, l2 is the span, V is the running speed of the rail vehicle, and V0 is the speed of the moving heat source;

[0048] S502. The Joule heat and friction heat generated by the contact between the bow and the catenary are input in the form of heat flux density through equivalent thermal power, and the heat flow per unit area is calculated through the heat flux density:

[0049]

[0050]

[0051] Where q is the heat flux, including friction heat flux and Joule heat flux, A is the nominal contact area between the friction pairs, and t is the time;

[0052] S503. Obtain the thermal-mechanical coupling analysis equilibrium equation of the pantograph-catenary system:

[0053]

[0054] P (i) [(F (i) ,T (i) )]=F (i) +P (i-1) [F (i-1) ,T (i) ]

[0055]

[0056] Where u is the displacement component, A is the heat source area, and the equation is solved using the displayed integration method as shown:

[0057]

[0058] Where [M] is the mass matrix, [C] is the damping matrix, [K] is the stiffness matrix, [P(F, T)] is the load vector, [C(T)] is the specific heat matrix, [K(T)] is the heat transfer matrix, Q(F, T) is the heat source vector, T is the temperature, F is the mechanical load obtained from the dynamic analysis, P is the node load, i is the time, P (i) is the node load at time i, P (i-1) is the node load at time i-1, F (i) is the mechanical load at time i, F (i-1) is the mechanical load at time i-1, Q (i) is the heat source at time i, Q (i-1)is the heat source at time i-1, T (i) is the temperature at time i, T (i-1) is the temperature at time i-1, q (i) is the heat flux density at time i;

[0059] S504. Combined with the initial temperature distribution of the pantograph and the three types of boundary conditions, the iteration step size and number of iteration steps are set, and according to the thermal-mechanical coupling analysis equilibrium equation of the pantograph-catenary system, the solution of the non-steady-state heat conduction of the pantograph at each moment is solved to obtain the temperature change, strain and stress results of each component of the pantograph carbon slide plate; among them, the temperature change, strain and stress results of each component of the pantograph carbon slide plate belong to the results of thermodynamic coupling analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 is a flow chart of the thermal-mechanical coupling simulation method of the present invention;

[0061] Figure 2 It is the finite element model of the pantograph carbon slide plate;

[0062] Figure 3 It is a schematic diagram of heat source movement;

[0063] Figure 4 This is the boundary condition diagram of the current collection of the pantograph carbon slide plate;

[0064] Figure 5 This is a comparison chart of the pantograph carbon slide plate temperature results. Figure 5 (a) is the graph of the temperature of the carbon strip midpoint changing with time; Figure 5 (b) Temperature of carbon strips and aluminum bracket of pantograph carbon slide; Figure 5 (c) is the temperature of the middle section of the pantograph carbon slide; Figure 5 (d) is the temperature diagram of the sheep horn;

[0065] Figure 6 The temperature distribution of the pantograph carbon strip changes with time;

[0066] Figure 7 Figure 7(a) is the stress result of the pantograph carbon slide plate. Figure 7(a) is the stress of the carbon strip and the aluminum bracket. Figure 7(b) is the pantograph carbon slide plate horn. Figure 7(c) is the stress history of the carbon strip midpoint. Figure 7(d) is the stress along the cross-sectional path of the carbon slide plate. Figure 7(e) is the stress in the middle section of the carbon slide plate. Figure 7(f) is the stress in the aluminum bracket airway.

[0067] Figure 8 The graph of carbon strip strain distribution changing with time. DETAILED DESCRIPTION

[0068] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0069] Example

[0070] like Figure 1 As shown, the present invention provides a method for thermal-mechanical coupling analysis of a rail vehicle pantograph-catenary system, comprising the following steps:

[0071] S1. 3D modeling of the pantograph carbon slide plate.

[0072] The pantograph carbon slide plate is the current collecting component of the high-speed train coupling system.

[0073] In this embodiment, since the aluminum bracket and other parts of the pantograph are mainly connected by spring tubes, the heat transfer area is small, the temperature cannot be effectively transmitted, and other parts of the pantograph do not show obvious temperature rise. Therefore, the three-dimensional model of the pantograph carbon slide plate is used in the analysis. Figure 2 As shown, the structural parameters of the pantograph carbon skateboard are shown in Table 3, wherein the three-dimensional model of the pantograph carbon skateboard is an existing model.

[0074] In this embodiment, the pantograph carbon slide plate is three-dimensionally modeled by simulation software, and material parameters are defined and assigned.

[0075] S2. According to the geometric features of the pantograph carbon slide plate, the three-dimensional model of the pantograph carbon slide plate is meshed to obtain a thermal-mechanical coupling finite element model.

[0076] The thermal-mechanical coupling finite element model is a physical model that reflects the geometric characteristics of the pantograph carbon slide plate.

[0077] In this embodiment, since the pantograph carbon slide plate has good symmetry, the thermal performance of the pantograph carbon slide plate is evaluated by performing a thermomechanical coupling analysis on the three-dimensional model of half of the pantograph carbon slide plate. According to the geometric characteristics of the pantograph carbon slide plate, the mesh type and mesh size are selected to mesh the three-dimensional model of the pantograph carbon slide plate to obtain a thermomechanical coupling finite element model; wherein the thermomechanical coupling finite element model is an existing model.

[0078] In this embodiment, the pantograph carbon slide plate is meshed according to the geometric features of the pantograph carbon slide plate to obtain a thermal-mechanical coupling finite element model, and the mesh type is assigned and divided for subsequent thermal analysis.

[0079] S3. Based on the thermal-mechanical coupling finite element model, the mesh type is assigned and divided, and three types of boundary conditions of the thermal-mechanical coupling finite element model are obtained through calculation.

[0080] The three types of boundary conditions include heat flux boundary conditions, convection heat transfer boundary conditions and radiation boundary conditions.

[0081] In this embodiment, the contact thermal boundary of the pantograph-catenary system is analyzed, and three types of boundary conditions of the model are given in combination with the heat source model of the pantograph carbon slide plate.

[0082] In this embodiment, the thermal boundary of the pantograph-catenary system contact takes into account three forms: heat conduction between the carbon bars, aluminum brackets and horns, heat convection with the environment, and heat radiation. The set boundary conditions include the thermal conductivity coefficient of the pantograph carbon slide plate, the convection heat transfer coefficient with the environment, and the thermal radiation coefficient.

[0083] S3. Due to the existence of the pull-out value, the moving track of the contact area on the surface of the slide is no longer a straight line parallel to the line direction, but a slanted line with a certain angle to the line direction. The size of this angle depends on the setting of the pull-out value and the running speed of the train. The moving speed of the contact area on the surface of the slide is actually the moving speed of the heat source in the coupling analysis. The moving speed of the heat source V0 is as follows: Figure 3 As shown:

[0084]

[0085] Where l1 is the pull-out value, θ is the angle between the pull-out value and the span, l2 is the span, V is the running speed of the rail vehicle, and V0 is the speed of the moving heat source.

[0086] The specific steps of S3 are as follows:

[0087] S301. Calculate the effect of heat conduction on the contact thermal boundary of the pantograph-catenary system:

[0088]

[0089] In the formula, Q c is the heat flow of heat conduction, k is the thermal conductivity, A is the area of ​​heat conduction, and dT / dx is the temperature gradient.

[0090] S302. Calculate the influence of thermal convection on the contact thermal boundary of the pantograph-catenary system:

[0091] Q d =αS(T f -T W )

[0092] Among them, the upper surface is a heat transfer mode of fluid sweeping the flat plate, and the convection heat transfer coefficient is expressed as:

[0093]

[0094] The front surface is a heat transfer mode in which the fluid sweeps across the column, and the convection heat transfer coefficient is expressed as:

[0095]

[0096] The heat transfer mode of the rear surface is natural convection heat transfer, and the convection heat transfer coefficient is expressed as:

[0097]

[0098] In the formula, Q d is the convective heat transfer energy, α is the convective heat transfer coefficient, S is the convective heat transfer area, T f is the temperature of the fluid, w is the temperature of the pantograph carbon slide surface, b is the width of the slide; u is the air velocity, which is equivalent to the train running speed here; Pr is called Prandtl constant; v is the kinematic viscosity of air; α is the thermal diffusivity of air; g is the gravitational acceleration; Δt is the difference between the surface temperature and the ambient temperature; l is the length of the convection surface; α v is the volume expansion coefficient, calculated using the inverse of the average temperature of the fluid in the boundary layer; n is the empirical coefficient; λ is the thermal conductivity of air; the values ​​of λ, v, and a are related to temperature.

[0099] S303. Calculate the influence of thermal radiation on the contact thermal boundary of the pantograph-catenary system:

[0100]

[0101] σ=5.677×10 -8 W / (m 2 ·k 4 )

[0102] In the formula, Q r is the energy generated by thermal radiation, T α is the atmospheric temperature; s is the surface temperature of the object; ε is the surface blackness coefficient, the surface blackness coefficient range of the aluminum bracket and the horn is 0.05-0.15, and the surface blackness coefficient of the skateboard is 0.9-0.95; σ is the Stefan-Boltzmann constant.

[0103] In this embodiment, considering that each surface of the pantograph carbon slide plate is impacted by the airflow in different ways, the convective heat exchange with the outside world belongs to the convective heat exchange without phase change, and the convective heat exchange of each surface of the pantograph carbon slide plate is calculated respectively. The comprehensive results of thermal radiation and absorption are expressed according to the Stefan-Boltzmann law. The material properties that need to be set include expansion coefficient, thermal conductivity, density, elastic modulus, Poisson's ratio, and specific heat capacity, as shown in Table 4 below.

[0104] S4. According to the three types of boundary conditions, the heat source of the rail vehicle during operation is analyzed to obtain the heat source analysis results, such as Figure 4 shown.

[0105] In this embodiment, the rail vehicle is in a dynamic state when it is running, and the heat source Q is mainly composed of the current heat Q r , friction heat Q, arc heat Q e And the temperature rise caused by factors such as air convection Q other composition.

[0106] In this embodiment, the heat source of the rail vehicle during operation is analyzed based on the results of the contact thermal boundary analysis of the pantograph-catenary system. The train operation is a dynamic current receiving process, and the heat flow is composed of the temperature rise changes caused by factors such as Joule heat, friction heat, and air convection.

[0107] The expression of the S4 heat source Q is:

[0108]

[0109] In this embodiment, the pantograph offline condition is not considered, so the arc heat is ignored;

[0110] Among them, according to the current thermal power and contact resistance, the current thermal Q is obtained I The expression is:

[0111] P I =(1-η)I 2 R c

[0112]

[0113] In this embodiment, current heat is the main factor of contact temperature rise. The current in the solution formula can be determined by circuit experiments, and the contact resistance is determined by calculation. The contact resistance model uses a contact resistance model based on the GW contact model, which takes into account the roughness of the contact surface, and the functional relationship between the contact resistance and the contact pressure, loop current and sliding speed. The correlation coefficient value is shown in Table 1.

[0114] Friction heat Q f The expression is:

[0115]

[0116] In this embodiment, friction heat is mainly generated by the friction work caused by the sliding electrical contact between the pantograph and the catenary, and is described by friction heat power. The friction force is calculated by combining the pantograph-catenary friction model under the combined action of fluctuating load and traction current of the Macquart method and the general global optimization method. The correlation coefficient values ​​are shown in Table 2.

[0117] According to the results of the contact thermal boundary analysis of the pantograph-catenary system, the temperature rise change Q is obtained. other The expression is:

[0118] Q other =Q c +Q r +Q d

[0119] In the formula, Q is the heat source, q i is the heat flux density, A is the nominal contact area between the friction pairs, τ is the time, P I is the current thermal power, R C is the contact resistance, I is the current, is the offline rate, ρ is the density, a, b, c, d, m, n, p, q are all unknown parameters, H is the hardness of the softer material, the unit is N·m -2 , E is the equivalent elastic modulus, the unit is Pa, V is the running speed of the rail vehicle, F, I, v are all variables, the units are N, A and km / h respectively, t is the running time of the rail vehicle, μ c is the Coulomb friction coefficient, μ s is the maximum friction coefficient, σ is the viscosity effect, ΔF is the pressure fluctuation amplitude, a1, a2, a3, b1, b3, d, v s are all fitted correlation coefficients, and z is an undetermined coefficient.

[0120] In this embodiment, the correlation coefficient values ​​in the formula are shown in Table 1 and Table 2.

[0121] S5. Based on the heat source analysis results, the heat flux per unit area is calculated by heat flux density. Combined with the temperature distribution at the initial moment and three types of boundary conditions, the iteration step size and number of iteration steps are set to solve the solution of the pantograph non-steady-state heat conduction at each moment and obtain the thermal-mechanical coupling analysis results.

[0122] In this embodiment, the heat flux per unit area is calculated by the heat flux density and conducted to other components of the pantograph through the carbon slide plate. Combined with the temperature distribution at the initial moment and three types of boundary conditions, the iteration step size and number of iteration steps are set to solve the solution of the pantograph's unsteady-state heat conduction at each moment and obtain the thermal-mechanical coupling analysis results.

[0123] The results of thermal-mechanical coupling analysis include temperature variation, strain and stress results of each component of the pantograph carbon slide.

[0124] The specific steps of S5 are as follows:

[0125] S501. Determine the speed V0 of the moving heat source:

[0126]

[0127]

[0128] Where l1 is the pull-out value, θ is the angle between the pull-out value and the span, l2 is the span, V is the running speed of the rail vehicle, and V0 is the speed of the moving heat source.

[0129] In this embodiment, the speed of the moving heat source needs to be determined first. Due to the existence of the pull-out value, the moving speed of the contact area on the slide, that is, the moving speed of the heat source in the temperature field, is a component of the train running speed.

[0130] S502. The Joule heat and friction heat generated by the contact between the bow and the catenary are input in the form of heat flux density through equivalent thermal power, and the heat flow per unit area is calculated through the heat flux density:

[0131]

[0132] Where q is the heat flux, including friction heat flux and Joule heat flux, A is the nominal contact area between the friction pairs, and t is the time.

[0133] S503. Obtain the thermal-mechanical coupling analysis equilibrium equation of the pantograph-catenary system:

[0134]

[0135] P (i) [(F (i) ,T (i) )]=F (i) +P (i-1) [F (i-1) ,T (i) ]

[0136]

[0137] where these equations are solved using the explicit integration method shown:

[0138]

[0139] Where [M] is the mass matrix, [C] is the damping matrix, [K] is the stiffness matrix, [P(F, T)] is the load vector, [C(T)] is the specific heat matrix, [K(T)] is the heat transfer matrix, Q(F, T) is the heat source vector, T is the temperature, F is the mechanical load obtained from the dynamic analysis, P is the node load, i is the time, P (i) is the node load at time i, P (i-1) is the node load at time i-1, F (i) is the mechanical load at time i, F (i-1) is the mechanical load at time i-1, Q (i) is the heat source at time i, Q (i-1) is the heat source at time i-1, T (i)is the temperature at time i, T (i-1) is the temperature at time i-1, q (i) is the heat flux at time i.

[0140] In this embodiment, according to the material properties of the pantograph carbon slide plate and the friction surface, the friction coefficient of the pantograph carbon slide plate is 0.3, the ambient temperature and the initial temperature of each component of the pantograph carbon slide plate are 20°C, and the train running speed is 160Km / h. The unit type of all components is C3D8RT.

[0141] S504. According to the thermal-mechanical coupling analysis balance equation of the pantograph-catenary system, the coupling analysis results of the temperature variation, strain and stress of each component of the pantograph carbon slide plate are obtained.

[0142] In this embodiment, the thermal coupling analysis results are as follows: Figure 5 As shown in the figure, the temperature relationship of the various components of the pantograph carbon slide is carbon bar> bracket> horn. Among them, the heating of the carbon bar is the most complex, involving multiple heat sources and heat transfer methods, and there are complex interactions. The temperature of the aluminum bracket is higher because the heat of the carbon bar is transferred to the bracket through heat conduction. In particular, the temperature in the middle area of ​​the bracket close to the heat source area of ​​the carbon bar is higher. The temperature of the horn is relatively low. The horn is far away from the mobile heat source and is mainly affected by the heat conduction of the aluminum bracket and the carbon slide. Figure 5 (a) is the temperature rise of the pantograph carbon slide at an ambient temperature of 20°C. The temperature rise of the pantograph carbon slide increases exponentially with time. It first rises rapidly with time, and then the rate of increase decreases. Figure 5 The corresponding curve has a larger slope at the beginning and then gradually decreases.

[0143] Figure 6 It is the temperature distribution of the carbon strip surface at different times of the pantograph carbon slide model under the action of thermal-mechanical coupling. As can be seen from the figure, the temperature distribution on the surface of the carbon strip is uneven, showing high temperature and low temperature areas, and the highest temperature area is concentrated in the contact area. This is due to the superposition effect of friction heat and current heat in this area, and the temperature is relatively high. The surface temperature of the carbon strip changes dynamically with time. As time goes by, the high temperature area gradually flows from the contact area to the edge area of ​​the pull-out value. During the conduction and diffusion of heat in the carbon strip, it gradually transfers to the area far away from the heat source, resulting in changes in temperature distribution. Due to the high-speed movement of the pantograph-net system, heat conduction occurs inside the carbon strip, forming a heat accumulation area on the surface of the carbon strip. Due to the effect of heat conduction, the heat storage area gradually merges together over time, and finally the temperature of the carbon strip contact area rises, becoming a high-temperature area of ​​the carbon strip. Therefore, it is speculated that heat accumulation areas will form at different positions of the carbon strip during the Z-shaped movement. Finally, with the diffusion and fusion of the heat accumulation area, the overall temperature of the carbon strip will rise in a short time.

[0144] Figure 7This is a comparison of the stress results of the various components of the pantograph carbon slide plate. The stress relationship of each component is bracket>carbon strip>ram horn. Figure 7 As shown in (d), in the middle area of ​​the aluminum bracket, the thermal stress is significantly higher than the stress at the end, and the maximum stress is 132MPa, which is located in the middle of the airway. This is because the middle area is close to the heat source and is affected by greater stress. The horns are far away from the heat source and are subject to less stress. The maximum stress is 36.1MPa, which is located in the contact area with the slide. The stress of the horns mainly comes from the heat conduction of the carbon strip and the change of ambient temperature. (d) is the midpoint stress curve of the carbon strip surface. The stress of the carbon strip increases exponentially with time. It first rises rapidly with time, and then the rate of increase decreases. The steady-state stress of the carbon strip is 19.5MPa, which is smaller than the bracket stress. 7(c) shows the stress and temperature distribution diagram along the edge of the pantograph carbon slide. It can be seen that on the cross section, the stress of the carbon strip first decreases and then increases from the upper surface to the lower surface along the cross section. A stress mutation occurs at the contact position with the aluminum bracket. The temperature gradually decreases from the upper surface to the lower surface along the cross section without obvious mutation.

[0145] like Figure 8 As shown in the figure, thermal expansion and contraction of carbon bars will cause thermal stress cracks to form on the contact surface of the bow and catenary. Thermal stress cracks are a special form formed by high temperature caused by current, and continuous thermal expansion and contraction will cause thermal fatigue of carbon bar materials, further expanding the original cracks. There is a risk of carbon bar material fracture in the crack area, leading to high-speed train failure. This is the surface strain distribution of carbon bars at an ambient temperature of 20°C. The surface strain of carbon bars changes dynamically over time. The contact area of ​​the bow and catenary is the main stress concentration area. The carbon bars undergo longitudinal reverse thermal warping deformation over time. Longitudinal reverse thermal warping deformation will cause uneven contact between the carbon bars and the contact network, resulting in local temperature increase. The combined effect of thermal stress and mechanical stress in a high temperature environment will further aggravate the deformation, microcracks and defects of the carbon bars. In this reciprocating cycle, the strength and durability of the carbon bars will be greatly reduced. In a high temperature environment for a long time, stress concentration and deformation will cause fatigue failure of the carbon bars to occur earlier and reduce fatigue life.

[0146] Table 1

[0147]

[0148] Table 2

[0149]

[0150]

[0151] Table 3

[0152]

[0153] Table 4

[0154]

[0155] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for thermal-mechanical coupling analysis of a railway vehicle pantograph-catenary system, characterized in that: The following steps are involved: S1. 3D modeling of the pantograph carbon slide plate; S2. According to the geometric characteristics of the pantograph carbon slide plate, the pantograph carbon slide plate is meshed to obtain a thermal-mechanical coupling finite element model; S3. Based on the thermal-mechanical coupling finite element model, assign and divide the mesh type, and obtain three types of boundary conditions of the thermal-mechanical coupling finite element model through calculation; S4. Analyze the heat source of the rail vehicle during operation according to the three types of boundary conditions to obtain the heat source analysis results; S5. Based on the heat source analysis results, the heat flux per unit area is calculated by heat flux density. Combined with the temperature distribution at the initial moment and three types of boundary conditions, the iteration step size and number of iteration steps are set to solve the solution of the pantograph non-steady-state heat conduction at each moment and obtain the thermal-mechanical coupling analysis results.

2. The method for thermal-mechanical coupling analysis of a rail vehicle pantograph-catenary system according to claim 1, characterized in that: The specific steps of S3 are as follows: S301. Based on the thermal-mechanical coupling finite element model, the grid type is assigned and divided, and the heat flux density boundary conditions are calculated: In the formula, Q c is the heat flow of heat conduction, k is the thermal conductivity, A is the area of ​​heat conduction, and dT / dx is the temperature gradient; S302. Based on the thermal-mechanical coupling finite element model, the grid type is assigned and divided, and the boundary conditions of the convective heat transfer are calculated: Q d =αS(T f -T W ) Among them, the upper surface is a heat transfer mode of fluid sweeping the flat plate, and the convection heat transfer coefficient is expressed as: The front surface is a heat transfer mode in which the fluid sweeps across the column, and the convection heat transfer coefficient is expressed as: The heat transfer mode of the rear surface is natural convection heat transfer, and the convection heat transfer coefficient is expressed as: In the formula, Q d is the convective heat transfer energy, α is the convective heat transfer coefficient, S is the convective heat transfer area, T f is the temperature of the fluid, w is the temperature of the pantograph carbon slide surface, b is the width of the slide; u is the air velocity, which is equivalent to the train running speed here; Pr is called Prandtl constant; C is the Grashof number correlation coefficient; v is the air kinematic viscosity; α is the thermal diffusivity of the air; g is the gravitational acceleration; Δt is the difference between the surface temperature and the ambient temperature; l is the convection surface length; α v is the volume expansion coefficient, calculated using the inverse of the average temperature of the fluid in the boundary layer; n is the empirical coefficient; λ is the thermal conductivity of air; the values ​​of λ, v, and a are related to temperature; S303. Based on the thermal-mechanical coupling finite element model, the grid type is assigned and divided, and the radiation boundary conditions are calculated: σ=5.677×10 -8 W / (m 2 ·k 4 ) In the formula, Q r is the energy generated by thermal radiation, T α is the atmospheric temperature; s is the surface temperature of the object; ε is the surface blackness coefficient, the surface blackness coefficient range of the aluminum bracket and the horn is 0.05-0.15, and the skateboard is 0.9-0.95; σ is the Stefan-Boltzmann constant; wherein the heat flux density boundary condition, the convection heat transfer boundary condition and the radiation boundary condition belong to three types of boundary conditions.

3. The method for thermal-mechanical coupling analysis of a rail vehicle pantograph-catenary system according to claim 1, characterized in that: The expression of the S4 heat source Q is: Among them, according to the current thermal power and contact resistance, the current thermal Q is obtained I The expression is: P I =(1-η)I 2 R c Friction heat Q f The expression is: According to the results of the contact thermal boundary analysis of the pantograph-catenary system, the temperature rise change Q is obtained. other The expression is: Q other =Q c +Q r +Q d In the formula, Q is the heat source, q i is the heat flux density, A is the nominal contact area between the friction pairs, τ is the time, P I is the current thermal power, R C is the contact resistance, I is the current, η is the offline rate, ρ is the density, a, b, c, d, m, n, p, q are all unknown parameters, H is the hardness of the softer material, the unit is N·m -2 , E is the equivalent elastic modulus, the unit is Pa, V is the running speed of the rail vehicle, F, I, v are all variables, the units are N, A and km / h respectively, t is the running time of the rail vehicle, μ c is the Coulomb friction coefficient, μ s is the maximum friction coefficient, σ is the viscosity effect, ΔF is the pressure fluctuation amplitude, a1, a2, a3, b1, b3, d, v s are all fitted correlation coefficients, and z is an undetermined coefficient.

4. The method for thermal-mechanical coupling analysis of a rail vehicle pantograph-catenary system according to claim 1, characterized in that: The specific steps of S5 are as follows: S501. Determine the speed V0 of the moving heat source: Where l1 is the pull-out value, θ is the angle between the pull-out value and the span, l2 is the span, V is the running speed of the rail vehicle, and V0 is the speed of the moving heat source; S502. The Joule heat and friction heat generated by the contact between the bow and the catenary are input in the form of heat flux density through equivalent thermal power, and the heat flow per unit area is calculated through the heat flux density: Where q is the heat flux, including friction heat flux and Joule heat flux, A is the nominal contact area between the friction pairs, and t is the time; S503. Obtain the thermal-mechanical coupling analysis equilibrium equation of the pantograph-catenary system: P (i) [(F (i) ,T (i) )]=F (i) +P (i-1) [F (i-1) ,T (i) ] Where u is the displacement component, A is the heat source area, and the equation is solved using the displayed integration method as shown: Where [M] is the mass matrix, [C] is the damping matrix, [K] is the stiffness matrix, [P(F, T)] is the load vector, [C(T)] is the specific heat matrix, [K(T)] is the heat transfer matrix, Q(F, T) is the heat source vector, T is the temperature, F is the mechanical load obtained from the dynamic analysis, P is the node load, i is the time, P (i) is the node load at time i, P (i-1) is the node load at time i-1, F (i) is the mechanical load at time i, F (i-1) is the mechanical load at time i-1, Q (i) is the heat source at time i, Q (i-1) is the heat source at time i-1, T (i) is the temperature at time i, T (i-1) is the temperature at time i-1, q (i) is the heat flux density at time i; S504. Combined with the initial temperature distribution of the pantograph and the three types of boundary conditions, the iteration step size and number of iteration steps are set, and according to the thermal-mechanical coupling analysis equilibrium equation of the pantograph-catenary system, the solution of the non-steady-state heat conduction of the pantograph at each moment is solved to obtain the temperature change, strain and stress results of each component of the pantograph carbon slide plate; among them, the temperature change, strain and stress results of each component of the pantograph carbon slide plate belong to the results of thermodynamic coupling analysis.

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