Railway train collision energy flow analysis method

Abstract

The present application relates to the technical field of rail train, and discloses a rail train collision energy flow analysis method, which comprises the following steps: determining a rail train collision energy flow analysis framework; establishing a train longitudinal collision finite element model and a train three-dimensional collision finite element model; establishing a train collision energy transmission path analysis model; and respectively analyzing the transformation, dissipation and transmission of collision energy in the collision process based on the train longitudinal collision finite element model and the train collision energy transmission path analysis model. The present application can comprehensively analyze the flow characteristics of collision energy in the collision process from the three aspects of transformation, dissipation and transmission of collision energy by establishing the train longitudinal collision finite element model and the train collision energy transmission path analysis model of two rail trains in the corresponding collision scene, which is of great significance for revealing the train collision energy flow mechanism, strengthening the understanding of the dynamic instability behavior of train collision, and improving the design method of train multi-stage crashworthiness structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rail trains, in particular to a rail train collision energy flow analysis method. BACKGROUND

[0002] The content of this part only provides background information related to the present application, which may not constitute prior art.

[0003] In the actual operation process of the rail train, the train collision accident cannot be avoided due to the influence of various factors such as natural environment change, equipment failure and personnel operation error. In the train collision process, the multi-stage energy absorption system can greatly reduce the damage degree of the vehicle and the risk of derailment. The train is a multi-vehicle coupled system, in the collision accident, not only the energy dissipation of the multi-stage energy absorption system, but also the kinetic energy conversion between the two colliding trains, and the energy transmission in the train body structure.

[0004] In the past research, more attention is paid to the energy dissipation law of the multi-stage energy absorption system under different marshalling, different mass and different parameter configuration, and the energy conversion process between the two colliding trains, the transmission and attenuation law of the collision energy in the train body structure, and the influence of the collision energy on the buckling behavior of the train body structure are ignored. In addition, the existing train collision simulation analysis model is established based on mature commercial nonlinear explicit dynamics software, which mainly analyzes the deformation of the train body structure from the stress and strain angle, and cannot directly show the transmission process of the collision energy along the train body structure. It cannot accurately judge whether the plastic deformation failure of the train body structure is caused by unreasonable structure design or by the unsmooth energy transmission path. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a rail train collision energy flow analysis method to at least overcome the problem that the traditional rail train collision energy analysis method only analyzes energy dissipation and does not pay attention to energy conversion, transmission and attenuation behavior.

[0006] The purpose of the present application is achieved by the following technical solutions:

[0007] The present application discloses a rail train collision energy flow analysis method, comprising the following steps:

[0008] Step S1. Determine the rail train collision energy flow analysis framework; the rail train collision energy flow analysis framework comprises a conversion layer, a dissipation layer and a transmission layer;

[0009] Step S2. Determine the collision scene of the two rail trains, and establish a train longitudinal collision finite element model and a train three-dimensional collision finite element model;

[0010] The train longitudinal collision finite element model and the train three-dimensional collision finite element model are respectively subjected to train collision process simulation analysis under corresponding collision scenes.

[0011] Step S3. Obtain the data field of the train three-dimensional collision finite element model after the train collision process simulation analysis in step S2, and establish a train collision energy transmission path analysis model according to the obtained data field;

[0012] Step S4. Based on the train longitudinal collision finite element model established in step S2 and the train collision energy transmission path analysis model established in step S3, analyze the conversion, dissipation and transmission of collision energy in the collision process from the three aspects of conversion layer, dissipation layer and transmission layer.

[0013] Further, in step S3, the train collision energy transmission path analysis model is established according to the obtained data field, which specifically includes:

[0014] Step S31. Obtain the stress and velocity data of each node of the car body structure of the rail train in the data field;

[0015] Step S32. According to the stress and velocity data of each node of the car body structure obtained in step S31, and combining the power flow calculation formula, the power flow of each node of the car body structure in each direction is calculated to obtain the power flow information of each node of the car body structure;

[0016] Step S33. The power flow information of each node of the car body structure obtained in step S32 is fed back to the calculation result of each step in the train collision process simulation analysis of the train three-dimensional collision finite element model in step S2;

[0017] Step S34. Use the visualization post-processing software Ensight to reproduce the train collision simulation process coupled with the power flow calculation result, display the direction and size of the power flow of each node of the car body structure in each direction, and obtain the train collision energy transmission path analysis model.

[0018] Further, in step S32, the power flow calculation formula is expressed as:

[0019]

[0020] In the above formula, I is the power flow vector of the node, I x , I y , I z are the components of I along the coordinate axes x, y and z, respectively, σ xx , σ yy , σ zz are the principal stress components of the node along the coordinate axes x, y and z, respectively, τ xy , τ xzτ yx τ yz τ zx τ zy These represent the shear stress components of the node along the coordinate axes x, y, and z, respectively, v x v y v z These are the velocity components of the node along the coordinate axes x, y, and z, respectively.

[0021] Furthermore, step S4 also includes:

[0022] Based on the train collision energy transfer path analysis model obtained in step S3, the relative energy attenuation coefficient and the absolute energy attenuation coefficient are defined to represent the attenuation rate of the energy wave during the transmission process, so as to analyze the attenuation behavior of the collision energy during the collision process.

[0023] Furthermore, the relative energy decay coefficient is expressed as:

[0024]

[0025] In the above formula: φ t Let be the relative energy decay coefficient at time t. This represents the power flow at node b in the vehicle structure at time t. Let represent the power flow at node a in the vehicle structure at time t; where node a and node b are two points on the same transmission path during the collision energy transfer process, and node a is located upstream of node b.

[0026] Furthermore, the absolute energy decay coefficient is expressed as:

[0027]

[0028] In the above formula: ψ t This represents the absolute energy decay coefficient at time t. This represents the power flow at node b in the vehicle structure at time t. This represents the total energy flowing into the vehicle structure before node b at time t.

[0029] The technical solutions of the embodiments of the present invention have at least the following advantages and beneficial effects:

[0030] The energy flow analysis method for train collisions disclosed in this invention establishes a longitudinal collision finite element model of two trains and an energy transfer path analysis model for the collision under the corresponding collision scenario. It can comprehensively analyze the energy flow characteristics during the collision process from three aspects: energy conversion, dissipation, and transfer. This method is of great significance for revealing the energy flow mechanism of train collisions, enhancing the understanding of the dynamic instability behavior of train collisions, and improving the design method of multi-level crashworthiness structures for trains. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 A schematic diagram of a train collision system formed by a two-track train according to an embodiment of the present application;

[0032] Figure 2 A flowchart of a method for analyzing train collision energy flow according to an embodiment of the present application;

[0033] Figure 3 A flowchart for establishing a train collision energy transmission path analysis model and a schematic diagram of a train collision energy transmission path analysis model according to an embodiment of the present application;

[0034] Figure 4 A schematic diagram of a continuum model D in a coordinate system according to an embodiment of the present application;

[0035] Figure 5 A schematic diagram of train marshalling, end structure configuration of train A and train B, and corresponding finite element models according to an embodiment of the present application;

[0036] Figure 6 A graph of the variation of interfacial force and energy dissipation rate with time during the collision process of train A and train B according to an embodiment of the present application;

[0037] Figure 7 A graph of the variation of acceleration with time during the collision process of train A and train B according to an embodiment of the present application;

[0038] Figure 8 A graph of the variation of jerk with time during the collision process of train A and train B according to an embodiment of the present application;

[0039] Figure 9 A graph of the energy absorption of each collision interface during the collision process of train A and train B according to an embodiment of the present application;

[0040] Figure 10 A graph of the longitudinal power flow of each car body of train B during the collision process of train A and train B according to an embodiment of the present application;

[0041] Figure 11 A graph of the relative energy attenuation coefficient and absolute energy attenuation coefficient between each car body of train B during the collision process of train A and train B according to an embodiment of the present application;

[0042] Figure 12 A graph of the energy flow vector of the car body underframe in the car body structure of train B during the collision process of train A and train B according to an embodiment of the present application. DETAILED DESCRIPTION

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments. The same reference numerals in the accompanying drawings represent the same components. It should be noted that the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the described embodiments of this invention without creative effort are within the scope of protection of this invention.

[0044] The present invention discloses a method for analyzing the energy flow of a train collision. It aims to comprehensively analyze the energy flow characteristics of the collision energy during the collision process by establishing a longitudinal collision finite element model and a collision energy transfer path analysis model of the train, starting from the perspective of energy flow of the collision energy when two trains collide.

[0045] To gain a clearer and more intuitive understanding of the methods disclosed in the embodiments of the present invention, the concept of energy flow of collision energy, which is innovatively proposed in the present invention, will be explained first.

[0046] First, refer to Figure 1 As shown, two colliding trains are considered as a single train collision system. During a collision, the two trains transition from a stable equilibrium state to an unstable, disordered state. In this state, the kinetic energy of the active collision system is the total collision energy of the entire system. The active collision system refers to the train with greater kinetic energy during the collision, also known as the energy outflow side. Conversely, the train with less kinetic energy can be considered the passive collision system, also known as the energy inflow side. For example, in a collision scenario where a moving train collides with a stationary train at a certain speed, the moving train can be considered the active collision system (i.e., the energy outflow side), and the stationary train can be considered the passive collision system (i.e., the energy inflow side).

[0047] During the whole collision process, a part of the collision energy is converted into kinetic energy of the passive collision system through the main collision interface, which can be called kinetic energy work, i.e. conversion of the collision energy; a part of the collision energy is dissipated by the energy absorption devices at the main collision interface and the secondary collision interface, which can be called dissipation of the collision energy; a part of the collision energy is transferred from one end of the car body structure of the rail train to the other end to ensure that the energy absorption devices at the main collision interface and each secondary collision interface can orderly participate in energy dissipation, which can be called transfer of the collision energy. It can be seen that during the whole collision process, the collision energy includes conversion, dissipation and transfer, and the conversion, dissipation and transfer of the collision energy can be collectively called energy flow of the collision energy. Among them, the main collision interface mentioned above refers to the interface between the train heads of the two rail trains before the collision of the two rail trains, and the secondary collision interface refers to the interface between the adjacent two car bodies in each rail train.

[0048] The rail train collision energy flow analysis method disclosed in the embodiments of the present application will be described below, wherein referring to Fig. 1, the method can include the following steps: Figure 1

[0049] Step S1. Determine the rail train collision energy flow analysis framework.

[0050] It can be understood that, in combination with the above description of energy flow, it can be seen that based on the fact that during the whole collision process, the collision energy includes three parts of conversion, dissipation and transfer, the rail train collision energy flow analysis framework can be divided into three levels in order to analyze the flow characteristics of the collision energy from different levels. Among them, the three levels can be conversion level, dissipation level and transfer level.

[0051] Further, the conversion level is a level from the perspective of the rail train, i.e. conversion of the collision energy between the energy outflow side and the energy inflow side; the dissipation level is a level from the perspective of the collision interface, which is composed of energy absorption devices on each rail train, accompanied by dissipation of the collision energy; the transfer level is a level from the perspective of the car body structure of the rail train, which is composed of the car body structure of the rail train, accompanied by transfer of the collision energy.

[0052] Step S2. Determine the collision scene of the two rail trains, and establish a train longitudinal collision finite element model and a train three-dimensional collision finite element model.

[0053] ​Generally, the collision scenarios of the two trains can include the following: scenario 1, one train is stationary, and the other train collides with the stationary train at a certain speed; scenario 2, two trains travel in the same direction, and the train behind collides with the train in front at a faster speed; scenario 3, two trains travel towards each other and collide at different speeds; and scenario 4, two trains travel towards each other and collide at the same speed. Research shows that scenario 1 is the typical collision scenario in various collision scenarios, and the average acceleration of the train after the collision in scenario 1 is the largest, that is, the collision response of the train in this scenario is the most dangerous, so scenario 1 is generally selected for collision analysis and crashworthiness design and checking.

[0054] On the basis of determining the collision scenario and establishing the train longitudinal collision finite element model and the train three-dimensional collision finite element model, the train longitudinal collision finite element model and the train three-dimensional collision finite element model are simulated and analyzed in the corresponding collision scenario.

[0055] Step S3. Obtain the data field of the train three-dimensional collision finite element model after the train collision process simulation analysis in step S2, and establish a train collision energy transfer path analysis model according to the obtained data field. The train longitudinal collision finite element model, the train three-dimensional collision finite element model and the train collision energy transfer path analysis model can be combined together and called a train collision energy flow analysis model.

[0056] It is worth noting that in the above-mentioned transfer layer, the transfer of collision energy includes two concepts of "collision internal energy" and "flow willingness". The collision internal energy refers to the energy level that the energy outflow side and the energy inflow side can transfer in the transfer layer. The greater the collision internal energy, the higher the energy level that the car body structure can transfer, and the greater the collision load that can be borne. The flow willingness is a representation of the energy transfer stability and smoothness difference of the car body structure. The greater the flow willingness, the greater the stability and smoothness of the energy transfer of the car body structure. At the same time, the side with greater collision internal energy can better transfer the collision energy through the car body structure to the remaining structure. The collision internal energy and the flow willingness are related to the specific car body structure.

[0057] On this basis, in order to better analyze the energy transfer characteristics in the train collision process and represent the energy flow willingness difference of the car body structure of the train, the power flow theory is introduced to show the transfer path of the collision energy in the car body structure.

[0058] Referring to Figure 3 As shown in FIG. 3, in step S3, establishing a train collision energy transfer path analysis model according to the obtained data field specifically includes:

[0059] Step S31. Obtain stress and velocity data of each node of the car body structure of the rail train in the data field;

[0060] Step S32. Calculate the power flow of each node of the car body structure in each direction according to the stress and velocity data of each node of the car body structure obtained in step S31, and combine the power flow calculation formula to obtain the power flow information of each node of the car body structure;

[0061] Step S33. Feedback the power flow information of each node of the car body structure obtained in step S32 to the calculation result of each step in the simulation analysis of the train collision process of the three-dimensional collision finite element model of the train in step S2;

[0062] Step S34. Use the visualization post-processing software Ensight to reproduce the train collision simulation process coupled with the power flow calculation result, display the direction and size of the power flow of each node of the car body structure in each direction, and obtain the train collision energy transfer path analysis model.

[0063] In step S32, the power flow calculation formula is expressed as:

[0064]

[0065] In the above formula, I is the power flow vector of the node, I x , I y , I z are the components of I along the coordinate axes x, y, and z, respectively, σ xx , σ yy , σ zz are the principal stress components of the node along the coordinate axes x, y, and z, respectively, τ xy , τ xz , τ yx , τ yz , τ zx , τ zy are the shear stress components of the node along the coordinate axes x, y, and z, respectively, v x , v y , v z are the velocity components of the node along the coordinate axes x, y, and z, respectively.

[0066] Further, the derivation process of the power flow calculation formula is as follows:

[0067] As the power flow containing stress and velocity information, it not only embodies the stress size of the structure internal particle (corresponding to the node in the embodiment of the present application), but also gives the velocity direction, so that the energy flow direction of the particle can be obtained according to the phase relationship between force and velocity, therefore the power flow can be used as the basis for judging the energy flow direction of the structure under transient response. The instantaneous power flow analysis is the energy distribution when the structure has transient response, which represents the instantaneous energy of the structure. As shown in the following formula: Figure 4 For the continuum model D in the coordinate system, d represents the unit area of the element, n i represents the unit normal of the element d surface, and the positive direction is from the inside of the element to the outside of the element.

[0068] The expression of the energy flow along the n i direction can be derived from the basic formula of power flow P=FV as follows:

[0069]

[0070] In the above formula, I n represents the energy passing through the unit area along the normal direction of the element per unit time; v i is the velocity of the unit area along the normal direction of the element; represents the tension of the element surface causing internal movement.

[0071] According to the Cauchy equation, the tension can be obtained as follows:

[0072]

[0073] In the above formula, σ ij is the stress tensor in the direction of the continuum element j, and n j is the normal direction of the continuum element.

[0074] Therefore, formula 1 can be expressed as:

[0075] I n =-v i σ ij n j =q j n j Formula 3

[0076] In the above formula, q j is the energy flow density vector in the direction of j.

[0077] According to formula 3, the expression of the energy flow density vector in the direction of j can be obtained as follows:

[0078] q j =-v i σ ij =-σ ij v i Formula 4

[0079] wherein formula 4 defines the velocity v i and the dot product of stress tensor σ ij . In the continuum structure, the energy flow density vector q j characterizes the way of energy transfer from one part of the continuum structure to another part, and the energy transfer of each node in any direction.

[0080] and the energy flow density vector q j represents the sum of power flow calculated by σ 1j , σ 2j , σ 3j , i.e.:

[0081]

[0082] In the above formula: q ij - the energy flow density corresponding to each stress component.

[0083] The continuum unit stress tensor σ ij is:

[0084]

[0085] In the above formula: σ x , σ y , σ z are the principal stress components along the coordinate axes x, y, z in the continuum, respectively, with symmetry; τ xy , τ xz , τ yx , τ yz , τ zx , τ zy are the shear stress components along the coordinate axes x, y, z in the continuum, respectively, with symmetry.

[0086] Then the corresponding energy flow density vector q ij is expressed as:

[0087]

[0088] In the above formula: v ij is the three velocity components along the coordinate axes in the Cartesian coordinate system, with unit of m / s 2 ,

[0089] Then the power flow calculation formula of each node of the continuum structure in each direction under the Cartesian coordinate system is as follows:

[0090]

[0091] Step S4. Based on the train longitudinal collision finite element model established in step S2 and the train collision energy transfer path analysis model established in step S3, the conversion, dissipation and transfer of collision energy in the collision process are analyzed from the three aspects of conversion layer, dissipation layer and transfer layer respectively.

[0092] Specifically, in step S4, the conversion and dissipation of collision energy in the collision process are analyzed from the conversion layer and the dissipation layer based on the train longitudinal collision finite element model; the transfer of collision energy in the collision process is analyzed from the transfer layer based on the train collision energy transfer path analysis model.

[0093] On this basis, the train collision energy transfer path analysis model can also be used to further analyze the attenuation behavior of collision energy in the collision process. Specifically, step S4 can further include:

[0094] Based on the train collision energy transfer path analysis model obtained in step S3, relative energy attenuation coefficient and absolute energy attenuation coefficient are defined to represent the attenuation speed of energy wave in the transfer process, so as to analyze the attenuation behavior of collision energy in the collision process.

[0095] The relative energy attenuation coefficient represents the percentage of the energy attenuation amount of the next node relative to the previous node in the same transfer path in the train body structure at time t in the collision energy transfer process and the energy ratio of the previous node.

[0096] The relative energy attenuation coefficient is expressed as:

[0097]

[0098] In the above formula: φ t is the relative energy attenuation coefficient at time t, represents the power flow of node b in the train body structure at time t, represents the power flow of node a in the train body structure at time t; wherein, nodes a and b are two nodes in the same transfer path in the collision energy transfer process, and node a is located upstream of node b, that is, the collision energy is transferred from node a to node b.

[0099] Correspondingly, the absolute energy attenuation coefficient represents the percentage of the energy attenuation amount of the next node relative to the incoming energy in the same transfer path in the train body structure at time t in the collision energy transfer process. The absolute energy attenuation coefficient is expressed as:

[0100]

[0101] In the above formula: ψ t represents the absolute energy attenuation coefficient at time t, Pb(t) represents the power flow of the b node in the car body structure at time t, Pb(t) represents the total energy in the car body structure before flowing into the b node at time t.

[0102] To better illustrate the method disclosed in the embodiments of the present application, the method disclosed in the embodiments of the present application will be further described below by taking the collision of two trains in the collision scenario of scenario 1 as an example.

[0103] Referring to Figure 5 , it is shown that the two trains colliding are defined as train A and train B, wherein train A and train B are both five-formation trains, further, the numbers of the car bodies in train A are M1-M5, and the numbers of the car bodies in train B are S1-S5. And it is assumed that train A and train B collide in scenario 1, that is, train A collides with the stationary train B at a certain speed, that is, train A is the active collision system or the energy inflow side, and train B is the passive collision system or the energy inflow side. Among them, the car body M1 of train A and the car body S1 of train B are the two train heads when colliding. In this embodiment, it is assumed that train A collides with the stationary train B at a speed of 36 km / h.

[0104] At the same time, the head cars (i.e. train heads) of train A and train B each include an anti-climbing energy-absorbing device and a main energy-absorbing device, and the adjacent car bodies of train A and train B each include a car coupler (including a buffer and a crush tube) and an anti-climbing energy-absorbing device. And, Figure 5 The steady-state crush force versus displacement curve of each energy-absorbing structure is also shown in FIG. 1. At the same time, the formation mass of train A and train B is shown in Table 1 below.

[0105] Table 1 Train formation mass

[0106]

[0107] On this basis, a train longitudinal collision finite element model of train A and train B and a train three-dimensional collision finite element model are established, and the train longitudinal collision finite element model and the train three-dimensional collision finite element model are respectively simulated and analyzed in the train collision process under scenario 1.

[0108] Secondly, the data field after the simulation analysis of the train three-dimensional collision finite element model is acquired to obtain the stress and speed data of each node of the train body structure in the data field, and the power flow of each node of the train body structure in each direction is calculated by combining the power flow calculation formula to obtain the power flow information of each node of the train body structure; subsequently, the obtained power flow information of each node of the train body structure is fed back to the calculation result of each step when the train three-dimensional collision finite element model is simulated and analyzed; finally, the train collision simulation process of the coupled power flow calculation result is reproduced by using the visual post-processing software Ensight, and the direction and size of the power flow of each node of the train body structure in each direction are displayed, so that the train collision energy transmission path analysis model is obtained.

[0109] On this basis, the transformation, dissipation and transmission of the collision energy in the collision process can be analyzed from the transformation layer, dissipation layer and transmission layer respectively based on the train longitudinal collision finite element model and the train collision energy transmission path analysis model. And the attenuation behavior of the collision energy in the collision process can be further analyzed based on the train collision energy transmission path analysis model.

[0110] Further, the transformation and dissipation of the collision energy in the collision process are analyzed from the transformation layer and the dissipation layer based on the train longitudinal collision finite element model, and the transmission of the collision energy in the collision process is analyzed from the transmission layer based on the train collision energy transmission path analysis model.

[0111] Specifically, as for the transformation layer, at least the curve graph of the interface force and the energy dissipation rate changing with time as shown in Figure 6 , the curve graph of the acceleration changing with time as shown in Figure 7 , and the curve graph of the jerk changing with time as shown in Figure 8 can be calculated after the simulation analysis of the train longitudinal collision finite element model. The energy dissipation rate refers to the change rate of the collision kinetic energy out of the energy flow in the collision process, which is used to reflect the degree of energy change. The jerk represents the change rate of the train acceleration with time, also called the force change rate, which reflects the degree of change of the acceleration. Generally, along the running direction of the train, the maximum jerk that the human body can withstand is about 20000 m / s 3 , and the maximum acceleration is about 2039 g / s.

[0112] As shown in Figure 6 , the energy dissipation process of the train A and the train B in the collision process is divided into three stages: stage 1 is a steady-state dissipation process; stage 2 is a variable-amplitude rapid dissipation process; and stage 3 is a step-by-step slow dissipation process.

[0113] Further, stage 1 is mainly the initial stage of the collision, the head car main energy absorption device stably crushes to absorb the collision energy, the middle car coupler buffer absorbs less energy, and the crushing force of the head car energy absorption device has little effect on the rest of the car body. Therefore, in stage 1, the energy dissipation rate has a small change amplitude, and it is a stable energy dissipation process.

[0114] In stage 2, the anti-climbing energy absorption device of the head car begins to participate in energy absorption, and the coupler crush tube of the middle car stably crushes to absorb energy. Therefore, the energy dissipation rate increases rapidly. Peak 1 is generated due to the participation of the anti-climbing energy absorption device of the interface M1-S1 (the main collision interface between M1 and S1), and peak 2 is generated due to the participation of the energy absorption device of the interface M1-M2 (the secondary collision interface between M1 and M2). However, due to the influence of the rest of the car body, the energy dissipation rate is a variable value.

[0115] In stage 3, as the coupler crush tube and energy absorption device of the middle car body gradually participate in energy absorption, the phenomenon of loading-unloading cycle occurs between the trains, and the energy dissipation rate presents a stepwise shock change.

[0116] As shown in Figure 7 , it can be seen from the acceleration curve that the maximum average acceleration of the car body M1 and the car body S1 during the collision process meets the standard requirement of less than 5g. However, as shown in Figure 8 , it can be seen from the jerk curve that the jerk of the car body M1 and the car body S1 near 0.2s is greater than the limit value of the jerk that the human body can withstand, and the peak value is 2190g / s, which has the risk of secondary collision of the driver and the attendant. Therefore, when analyzing the acceleration of the train, the jerk should be analyzed to avoid the jerk exceeding the limit value that the human body can withstand.

[0117] It is worth noting that by analyzing the energy conversion capacity between the two trains in each collision scenario in the conversion layer, the most dangerous collision scenario under the same flow capacity is obtained, and the crashworthiness design is carried out in the collision scenario, which can maximize the safety of the driver and the attendant. At the same time, through the analysis of the energy conversion of the train collision, the peak value of the energy dissipation rate can be reduced, the stability of the energy conversion can be increased, and the peak value of the jerk can be less than the limit value that the human body can withstand, so as to avoid the driver and the attendant from suffering severe secondary collision.

[0118] As for the dissipation layer, after simulating the train collision process of the train longitudinal collision finite element model, the energy absorption diagram of each collision interface as shown in Figure 9 can be calculated. On this basis, combined with the flow capacity (FC) calculation formula in the corresponding collision scenario, and according to the flow capacity and the energy absorbed by each collision interface, the longitudinal interface energy design coefficient (DCECC) can be calculated.

[0119] wherein, the flow capacity (FC) is a difference representation of the kinetic energy of the energy outflow side converted into the energy inflow side, which embodies the energy exchange capacity between the two trains. The greater the flow capacity, the stronger the energy outflow potential of the energy outflow side, the stronger the energy exchange capacity between the two trains, and vice versa, which means the weaker the energy exchange capacity. In scenario 1, the calculation formula of the flow capacity is expressed as:

[0120]

[0121] In the above formula, m A and V A are the mass and speed of train A, and m B and V B are the mass and speed of train B. In this embodiment, in combination with the train marshalling mass shown in Table 1 and the speed of train A being 36 km / h, the flow capacity FC = 8690.2 kJ can be calculated. At this time, the longitudinal interface energy design coefficient (DCECC) of each collision interface can be calculated according to the calculation formula of the longitudinal interface energy design coefficient.

[0122] wherein, the calculation formula of the longitudinal interface energy design coefficient is expressed as:

[0123]

[0124] In the above formula, E i is the energy absorbed by each collision interface, that is, the energy dissipation capacity of each collision interface. It can be understood that by researching the energy dissipation law of each collision interface of different marshalling trains and introducing the longitudinal interface energy design coefficient to represent the lower limit of the energy dissipation capacity design of each collision interface, the product of the longitudinal interface energy design coefficient and the flow capacity is the lower limit of the energy absorption capacity of each collision interface, which is the basis for the design of the multi-level crashworthiness structure parameters of the train and the guarantee of sufficient energy absorption capacity of each interface.

[0125] As for the transfer layer, the lower side wall of the car body structure of the rail train is one of the main transfer paths of the collision energy in the car body structure, which reflects the size of the collision energy transferred by the car body structure to a certain extent. Therefore, the power flow at the longitudinal center lower side wall node of each car body of the stationary train B can be collected to represent the collision energy passing through the car body structure. At this time, based on the train collision energy transfer path analysis model, at least the longitudinal power flow curve diagram of each car body of train B (that is, the energy inflow side) can be obtained as shown in Figure 10 .

[0126] In combination with Figure 10As shown by the curves and arrows, during the collision, the collision energy is gradually transferred from car body S1 of train B to car body S5, exhibiting a significant transfer hysteresis characteristic. Based on this, the maximum longitudinal power flow value of each car body of train B is used to characterize the energy attenuation. Combining this with the aforementioned formulas for calculating the relative and absolute energy attenuation coefficients, the relative and absolute energy attenuation coefficients between the car bodies of train B are calculated as follows: Figure 11 As shown. In Figure 11 In this context, S2 / S1 represents the energy attenuation coefficient from vehicle body S1 to vehicle body S2, and so on.

[0127] Depend on Figure 11 It can be seen that although the relative energy attenuation coefficient and the absolute energy attenuation coefficient between the various car bodies of train B are not exactly the same, overall, the energy attenuation from car body S1 to car body S5 is 79%.

[0128] Meanwhile, previous studies have shown that the asymmetry of lateral stiffness and strength of the car body underframe floor structure is a factor in the lateral instability of trains in collisions. Therefore, in order to better analyze how the holes on the car body underframe induce structural deformation and lead to the lateral buckling instability of the train, an analysis can be conducted from the perspective of energy.

[0129] Specifically, based on the train collision energy transfer path analysis model, at least the following can be obtained: Figure 12 The vector diagram shows the energy flow of the underframe in the car body structure of train B during a collision. From... Figure 12 As can be seen, as the collision progresses, the collision energy gradually accumulates in areas prone to structural deformation. When the accumulated energy exceeds the maximum energy the structure can withstand, deformation occurs. Furthermore, the energy distribution is more disordered on the side of the vehicle chassis with holes, with significantly more energy than on the side without holes. Therefore, it can be concluded that asymmetry in the stiffness and strength of the vehicle structure easily causes energy to accumulate on the weaker side, leading to structural deformation.

[0130] Understandably, this invention establishes a train collision energy transfer path analysis model to analyze the transfer law of collision energy in the car body structure of the rail train, studies the differences in energy transfer caused by different energy attenuation coefficient structural forms, can effectively avoid the plastic deformation failure of the car body structure caused by energy accumulation, explore the essential cause of buckling instability of the car body structure, and provide theoretical support for the design of the car body structure.

[0131] As can be seen from the above, the rail train collision energy flow analysis method disclosed by the embodiment of the present application can comprehensively analyze the flow characteristics of the collision energy in the collision process from the three aspects of the transformation, dissipation and transmission of the collision energy by establishing the train longitudinal collision finite element model of two rail trains and the train collision energy transmission path analysis model under the corresponding collision scene, has important significance for revealing the train collision energy flow mechanism, strengthening the understanding of the dynamic instability behavior of the train collision, and perfecting the train multi-level crashworthiness structure design method.

[0132] Meanwhile, the train collision energy transmission path analysis model established by the present application can also analyze the attenuation behavior of the collision energy in the collision process, analyze the attenuation law of the collision energy in the train body structure and the influence on the deformation of the train body structure through the energy attenuation coefficient, and can avoid the unreasonable structure design to cause the energy aggregation to lead to the plastic deformation of the structure.

[0133] The above is only the preferred embodiment of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method of rail vehicle crash energy flow analysis, characterized by, The method comprises the following steps: Step S1. Determine a rail train collision energy flow analysis framework; the rail train collision energy flow analysis framework comprises a conversion layer, a dissipation layer and a transmission layer; Step S2. Determine a collision scenario of two rail trains, and establish a train longitudinal collision finite element model and a train three-dimensional collision finite element model; Step S3. Obtain a data field of the train three-dimensional collision finite element model after the train collision process simulation analysis in step S2, and establish a train collision energy transmission path analysis model according to the obtained data field; Step S4. Based on the train longitudinal collision finite element model established in step S2 and the train collision energy transmission path analysis model established in step S3, analyze the conversion, dissipation and transmission of collision energy in the collision process from the three aspects of the conversion layer, the dissipation layer and the transmission layer; In step S3, the train collision energy transmission path analysis model is established according to the obtained data field, which comprises: Step S31. Obtain stress and speed data of each node of the car body structure of the rail train in the data field; Step S32. According to the stress and speed data of each node of the car body structure obtained in step S31, and combining the power flow calculation formula, the power flow of each node of the car body structure in each direction is calculated to obtain the power flow information of each node of the car body structure; Step S33. The power flow information of each node of the car body structure obtained in step S32 is fed back to the calculation result of each step when the train three-dimensional collision finite element model is simulated in step S2; Step S34. The train collision simulation process coupled with the power flow calculation result is reproduced by using the visualization post-processing software Ensight, and the power flow direction and size of each node of the car body structure in each direction are displayed to obtain the train collision energy transmission path analysis model; In step S32, the power flow calculation formula is expressed as: The step S4 further comprises: In the above formulae: I is the power flow vector of the node, , , are the components of I along the coordinate axes x , y , z , are the principal stress components of the node along the coordinate axes , , x , y , z , , x , y , z , , x , y , z are the velocity components of the node along the coordinate axes 2. The rail vehicle crash energy flow analysis method of claim 1, wherein, Based on the train collision energy transmission path analysis model obtained in step S3, the relative energy attenuation coefficient and the absolute energy attenuation coefficient are defined to represent the attenuation speed of the energy wave in the transmission process, so as to analyze the energy attenuation behavior in the collision process. The relative energy attenuation coefficient is expressed as:

3. The rail vehicle crash energy flow analysis method of claim 2, wherein, The absolute energy attenuation coefficient is expressed as: In the above formula: is t the relative energy attenuation coefficient at the time instant, denotes t the power flow in the vehicle body structure at the time instant, b denotes the power flow in the vehicle body structure at the time instant; t wherein, a denotes a the power flow in the vehicle body structure at the time instant; b the nodes are two points in the same transfer path during the crash energy transfer, and a the node is located b upstream of the node.

4. The rail vehicle crash energy flow analysis method of claim 2, wherein, ​ in the above formula: denotes t the absolute energy decay coefficient at time instant denotes t the power flow in the car body structure at time instant b denotes the total energy in the car body structure before the flow into t node at time instant b node at time instant

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