Dynamic wear calculation method for friction block of brake pad of high-speed train

Abstract

The invention discloses a dynamic wear calculation method for a friction block of a brake pad of a high-speed train. The dynamic wear calculation method comprises the following steps: firstly, establishing a finite element model of the friction block and a brake disc; then, finite element software ABAQUS is used for carrying out dynamics-interface wear coupling simulation solution; then, a subprogram FRICCOEF is called to carry out data recording and transmission analysis under implicit dynamics; then, a subprogram UMESHMOTION is called to carry out wear analysis; and finally, updating the grid and carrying out cyclic calculation. According to the dynamic wear calculation method for the brake pad friction block of the high-speed train, dynamic characteristics of wear of the friction block are considered, the wear state of the friction block is analyzed through finite element simulation, and the dynamic wear calculation method has great significance in guiding design, operation and maintenance of the brake pad friction block of the high-speed train.

Description

Technical Field

[0001] The invention relates to the field of high-speed train brake pads, and in particular to a method for calculating dynamic wear of friction blocks of high-speed train brake pads. Background Art

[0002] In recent years, the development of high-speed railway systems has become a key component of modern transportation. The system is known for its ability to efficiently transport passengers at high speed over long distances. However, it is crucial to ensure the safety and reliability of high-speed train braking under various operating conditions. Among them, the mechanical braking system plays a vital role in the deceleration and parking process of the train. The system includes multiple components such as brake discs, brake pads and actuators. The braking interface usually produces complex interface behaviors, such as high-frequency self-excited friction vibrations, which will aggravate the surface wear of the friction block, causing the friction block to fall off or even fall off, thus threatening the safety of train operation. These components are subjected to a variety of different forces and dynamic effects during braking. Through finite element analysis, these complex geometries and material properties can be accurately modeled to simulate the contact, deformation and stress distribution between components during braking. Wear is an issue that cannot be ignored in the braking system, especially during the long-term operation of high-speed trains. Finite element analysis can simulate the wear of the contact surface of the friction pair and predict the wear depth, mode and wear rate under different operating conditions. This helps to optimize the system design and ensure efficient and safe performance under actual operating conditions.

[0003] Abaqus software provides users with the UMESHMOTION subroutine to achieve wear simulation. However, this subroutine can only simulate static wear that does not consider time effects, such as contact surfaces that are only applicable to stationary parts and low-speed sliding contacts, while ignoring the dynamic effects of the model (dynamic factors such as acceleration and vibration). Therefore, improvements have been made to address the limitations of the model so that the model can more comprehensively and accurately predict wear behavior under complex working conditions. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, the present invention provides a method for calculating the dynamic wear of the friction block of a high-speed train brake pad. The method for calculating the dynamic wear of the friction block of a high-speed train brake pad takes the dynamic characteristics of the friction block wear into consideration and calculates the dynamic wear of the friction block through finite element simulation, which is of great significance for guiding the design and maintenance of the friction block of the brake pad of a high-speed train.

[0005] The technical solution of the present invention to solve the above technical problems is:

[0006] A method for calculating dynamic wear of a high-speed train brake pad friction block comprises the following steps:

[0007] Step 1: Establish the finite element model of the friction pad and brake disc;

[0008] Step 2: Use finite element software ABAQUS to perform dynamics-interface wear coupling simulation solution;

[0009] Step 3: Call subroutine FRIC_COEF to perform data recording and transfer analysis under implicit dynamics;

[0010] Step 4: Call subroutine UMESHMOTION to perform wear analysis;

[0011] Step 5: Update the grid and loop the calculation.

[0012] Preferably, in step 1, the steps of constructing the finite element model are:

[0013] Step 101: Create a three-dimensional model of the friction block and the brake disc, import the created three-dimensional model into finite element software, and assemble it;

[0014] Step 102: assigning material properties, wherein the material properties include but are not limited to density, specific heat capacity, thermal expansion coefficient, Poisson's ratio, and Young's modulus;

[0015] Step 103: Setting up interaction;

[0016] Step 104: Set loads and mesh.

[0017] Preferably, in step 2, in step 102, the material properties include but are not limited to density, specific heat capacity, thermal expansion coefficient, Poisson's ratio, and Young's modulus.

[0018] Preferably, in step 2, a sequential coupling method is used to solve the dynamics-interface wear coupling simulation, so that the entire simulation process is discretized into N incremental steps, and a wear calculation is performed in each incremental step.

[0019] Preferably, in step 3, the transfer analysis includes using the FRIC_COEF subroutine to receive the contact stress, contact slip and wear coefficient under implicit dynamics, and storing them in the common variable module to calculate the wear amount, specifically:

[0020] According to the Achard empirical formula, the normal load and sliding distance data are obtained in the data acquisition system of the experimental device, and the wear volume of the friction block is measured after the experiment to obtain the wear coefficient k, which is defined as follows:

[0021]

[0022] Where V is the wear volume (mm 3 ), F is the normal load (N), d is the sliding distance (m), and the wear coefficient is considered as a fixed value in the current wear model.

[0023] Combining the wear coefficient obtained from the experiment with the implicit dynamics calculation results, the contact stress and contact slip of each node in each incremental step are obtained. The calculation expression of the wear amount is as follows:

[0024]

[0025] Where: dh i is the wear amount of the node in one incremental step, k is the wear coefficient of the friction block, H is the material hardness of the friction block surface, is the average contact pressure of the node within 0.01s, ds i is the relative sliding distance of the node within 0.01s;

[0026] The total wear depth is:

[0027]

[0028] Where: n is the current time step.

[0029] Preferably, in step 4, the calculated wear amount is applied to the nodes of the friction block using the subroutine UMESHMOTION and the ALE algorithm to perform a wear effect analysis; specifically,

[0030] Step 401: Calculate the volume change V t :

[0031] V t =V0-A·Δh(t);

[0032] Where: A is the surface area affected by wear, V0 is the initial volume;

[0033] Step 402: Obtain the boundary surface S after wear t :

[0034] S t =S0-ΔS(Δh(t));

[0035] Where: S0 is the initial boundary surface; ΔS is the change in the boundary surface caused by wear, which is described by the wear depth and surface differential:

[0036]

[0037] Where: Γ is the boundary of the wear area, h is the function of wear depth over time, and is the gradient of wear depth in x and y directions;

[0038] Step 403: The volume change V in step 401 and step 402 ist and the boundary surface S t Substitute into the mass conservation equation, where the mass conservation equation is:

[0039]

[0040] Where: x is the spatial coordinate of the grid; ρ is the material density; c = vv mesh is the relative velocity, where v is the material velocity; v mesh is the grid velocity; n0 is the external normal vector of the boundary surface;

[0041] get:

[0042]

[0043] Where: n1 is the outer normal vector of the boundary surface under wear, v wear Indicates the relative movement speed of the wear part, n wear is the normal vector of the worn surface; v wear =vv mesh , where v is the material velocity; v mesh is the grid speed;

[0044] n wear The derivation formula is as follows:

[0045] n local =R T ·n global ;

[0046] Where: n global is the normal vector in the global coordinate system, n local is the normal vector in the local coordinate system, R is the rotation matrix from local to global; R T is the transpose of the matrix, used to convert the global vector into a local vector;

[0047]

[0048] Where: N is the number of incremental steps or nodes; n global,i is the global normal vector of the ith increment or node.

[0049] Preferably, in step S5, the finite element model is updated using the ALE algorithm, and it is determined whether the calculation time has ended. If the time has not ended, the wear coupling calculation is performed; if the time has ended, the calculation is completed.

[0050] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0051] The dynamic wear calculation method of the high-speed train brake pad friction block of the present invention takes the dynamic characteristics into consideration, so that the wear depth obtained by simulation is more in line with reality, which is of great significance for guiding the design and maintenance of the high-speed train brake pad friction block. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 A model diagram of a high-speed train brake disc and friction block used in the present invention.

[0053] Figure 2 The present invention is a flow chart of the method for calculating dynamic wear of the friction block of the brake pad of a high-speed train.

[0054] Figure 3 The finite element model meshing and sampling point setting diagram of the present invention, wherein: Figure 3 (a) is a simplified three-dimensional diagram of the braking system. Figure 3 (b) is the finite element model of the braking system after meshing. Figure 3 (c) Sampling points N1-N6 on the friction block surface (c).

[0055] Figure 4 The wear depth distribution and wear amount of the friction block in the friction direction of the present invention vary with time, wherein: Figure 4 (a) is a schematic diagram of the change of wear depth of nodes on the friction block surface over time. Figure 4 (b) is a schematic diagram of the wear depth of 65Mn surface changing with time. Figure 4 (c) is a schematic diagram of the change of wear depth of 304 surface with time. Figure 4 (d) is a schematic diagram of the change of 51CR surface wear depth over time. Figure 4 (e) Schematic diagram of the wear depth of 60SM surface changing with time.

[0056] In the figure: 1-brake disc; 2-clamp; 3-friction block; 4-fixing block; 5-disc spring. DETAILED DESCRIPTION

[0057] The present invention is further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0058] A simplified three-dimensional model of the test device is established in Abaqus software, such as Figure 1 As shown, the main components of the three-dimensional model include: brake disc 1, clamp 2, friction block 3, fixing block 4, disc spring 5; the disc spring 5 has 4 different materials, namely 65Mn spring steel, 304 stainless steel, 51CrV4 spring steel and 60Si2MnA spring steel, and 65Mn, 304, 60SM and 51CR are used to replace friction blocks of these thicknesses. In this embodiment, the disc springs of 4 thicknesses are used as variables.

[0059] The analysis process of the method for calculating dynamic wear of the friction block of the brake pad of a high-speed train of the present invention is as follows: Figure 2 As shown, the following steps are included:

[0060] Step 1: Establish the finite element model of friction pad and brake disc;

[0061] In this embodiment, establishing the finite element model includes establishing a three-dimensional model of the friction block and the brake disc, assigning material properties, setting interactions, setting loads, and dividing the grid, wherein:

[0062] Step 101: Create a three-dimensional model of the friction block and the brake disc, import the created three-dimensional model into finite element software, and assemble it;

[0063] Step 102: assigning material properties: assigning material properties such as density, Poisson's ratio, and Young's modulus;

[0064] Step 103: Set the interaction and boundary conditions: According to the contact state and boundary conditions in the experimental device, the contact between the brake disc and the friction block is set to surface-to-surface contact, and the contact characteristics between them are defined as follows: the penalty function friction formula is used for tangential behavior, and hard contact is used for normal behavior; the friction coefficient is set to 0.45 in wear analysis and implicit dynamic analysis, and the friction coefficient is defined as 0.02-0.60 (interval of 0.02) in complex modal analysis. The five holes on the brake disc use coupling constraints and set the control point at the center point of the large hole, then only apply a rotation speed of 100rpm in the Y direction to this point, and restrict the five degrees of freedom in other directions. In order to ensure the reliability of calculation and the convergence of the model, in the connection structure of the disc spring, a binding constraint is used between the fixed block and the fixture, a surface-to-surface contact (a penalty function of 0.16 in the tangential friction coefficient and normal hard contact) is used between the friction block and the fixed block, a binding constraint is used for the contact part between the disc spring and the friction block, and a surface-to-surface contact (tangential frictionless and normal hard contact) is used for the contact part between the fixture and the disc spring; a coupling constraint is used for the two connecting holes of the fixture, the control point is set to the midpoint of the line connecting the centers of the two holes, and a clamping force of 535.2N is applied to the point by converting the force of the 500N clamp of the experimental device; the sampling frequency of the braking system is 50kHz;

[0065] Step 104: Divide the grid;

[0066] In Abaqus, structured mesh and swept mesh are selected according to the structural characteristics of the model. The density is controlled by setting the mesh seed, C3D8R hexahedral mesh elements are selected, and the partition and mesh gradient techniques are combined to use dense meshes in important areas and keep coarse meshes in other areas.

[0067] Step 2: Use finite element software ABAQUS to perform dynamics-interface wear coupling simulation solution;

[0068] In order to realize the dynamics-interface wear coupling simulation, first of all, it is necessary to define the total analysis time as 3s. To ensure the calculation accuracy, the implicit dynamics analysis time is 0.01s each time, and each static analysis used to update the grid is an incremental step. The cycle is one implicit dynamics and one static analysis, with a total of 300 cycles.

[0069] Step 3: Call subroutine FRIC_COEF to record and transfer data under implicit dynamics;

[0070] The FRIC_COEF subroutine is used to receive the contact stress, contact slip and wear coefficient under implicit dynamics, and the calculated wear amount is stored in the public variable module in Fortran according to the node number as the data label;

[0071] The basic equation of implicit dynamics is:

[0072]

[0073] Where: M is the mass matrix, C is the damping matrix, K is the stiffness matrix, is the acceleration vector, is the velocity vector, u(t) is the displacement vector, and F(t) is the external force vector.

[0074] In the implicit dynamics method, incremental steps are used to iteratively solve dynamic problems. Each step of the calculation solves a set of nonlinear equations through numerical iteration. The stability of the implicit method enables it to be effectively calculated even with large step sizes.

[0075] According to the Achard empirical formula, the normal load and sliding distance data are obtained in the data acquisition system of the experimental device, and the wear volume of the friction block is measured after the experiment to obtain the wear coefficient k, which is defined as follows:

[0076]

[0077] Where V is the wear volume (mm 3 ), F is the normal load (N), d is the sliding distance (m), and the wear coefficient is considered as a fixed value in the current wear model.

[0078] Combining the wear coefficient obtained from the experiment with the implicit dynamics calculation results, the contact stress and contact slip of each node in each incremental step are obtained. The calculation expression of the wear amount is as follows:

[0079]

[0080] In the formula, dhi is the wear amount of the node in one increment, k is the wear coefficient of the friction block, H is the material hardness of the friction block surface, is the average contact pressure of the node within 0.01s, ds i is the relative slip distance of the node within 0.01s;

[0081] Δh(t) is the total wear depth, accumulated over time. It can be calculated by calculating the wear depth dh for all increments. i Adding up, we get:

[0082]

[0083] Where: n is the current time step;

[0084] The above expression represents the total wear depth from the initial time to the current time t.

[0085] Step 4: Call the subroutine UMESHMOTION and ALE algorithm to update the grid and loop the calculation;

[0086] In this embodiment, the calculated wear amount is applied to the friction block node through the subroutine UMESHMOTION and ALE algorithm to perform wear effect analysis, where:

[0087] In the Arbitrary Lagrange-Euler (ALE) algorithm, the mass conservation equation can be expressed as:

[0088]

[0089] Where: x is the spatial coordinate of the grid, ρ is the material density, V t is the time-varying control volume, S t Yes V t The boundary surface of c = vv mesh is the relative velocity, v is the material velocity, v mesh is the grid velocity and n0 is the external normal vector of the boundary surface; this mass conservation equation describes the time variation of the mass within the control volume and the mass flow through the control volume boundary.

[0090] The special feature of the mass conservation equation in the ALE algorithm is that it allows the movement of the mesh to be independent of the movement of the material, which can effectively handle moving boundaries and deforming regions.

[0091] Consider how to reflect the changes in the material surface due to wear through the mass conservation equation in the ALE framework; therefore, it is assumed that the wear volume can be expressed as a time function Δh(t) to represent the change in wear depth over time. This wear depth will directly affect the change in control volume and surface area.

[0092] As wear occurs, the control volume V t will decrease; assuming the wear depth is Δh(t), the volume change can be approximately expressed as:

[0093] V t =V0-A·Δh(t);

[0094] Where: A is the surface area affected by wear, V0 is the initial volume.

[0095] Wear changes the shape and position of the surface, causing it to change over time. The surface area S of the boundary surface t It can be defined as:

[0096] S t =S0-ΔS(Δh(t));

[0097] Where: S0 is the surface area of ​​the initial boundary surface, ΔS is the change in the surface area of ​​the boundary surface caused by wear, which can be defined as a function of the wear depth;

[0098] In this example, ΔS can be described by the wear depth and the surface differential:

[0099]

[0100] Where: Γ is the boundary of the wear area; h is the function of wear depth over time; and is the gradient of the wear depth in the x and y directions; this formula takes into account the non-uniformity of the wear area and calculates the area change of the entire surface by integration.

[0101] To further refine this, the change in surface area due to wear can be reflected in the surface integral term:

[0102]

[0103] Where: v wear Indicates the relative motion speed of the worn part, v wear =vv mesh , v is the material velocity; v mesh is the grid velocity, which is equivalent to saying that v wear =c;n wearis the normal vector of the worn surface; in this equation, ΔS(t) represents the additional surface area introduced by wear, which will change dynamically over time to reflect the wear effect;

[0104] n wear The derivation formula is as follows:

[0105] n local =R T ·n global ;

[0106] Where: n global is the normal vector in the global coordinate system, n local is the normal vector in the local coordinate system, R is the local to global rotation matrix, which represents the transformation between coordinate systems; R T is the transpose of the matrix, used to convert the global vector into a local vector;

[0107]

[0108] Where: N is the number of incremental steps or nodes. global,i is the global normal vector of the ith incremental step or node. This means that the normal vector of the wear surface is obtained by converting the global normal vectors of multiple time steps or nodes into the local coordinate system and gradually accumulating them.

[0109] Finally, the ALE algorithm is used to update the finite element model and determine whether the calculation time has ended. If the time has not ended, the wear coupling calculation is performed; if the time has ended, the calculation is completed.

[0110] In this embodiment, the process of implementing the dynamics-interface wear coupling simulation model in the present invention is as follows Figure 2As shown in the figure, firstly, an inp file is created for pre-processing (including specifying the adaptive grid area) and setting the analysis step process. The wear analysis time is 3s. In the Fortran compilation, the FRIC_COEF subroutine is used to set the friction coefficient in the implicit dynamics analysis and extract the relative sliding distance and contact pressure within 0.01s. The wear depth is calculated after taking the average value. By specifying the common variable module comv, the data is passed to the UMESHMOTION subroutine so that it uses the arbitrary Lagrangian-Euler algorithm to assign the wear amount to the friction block surface node to realize the wear analysis. It is worth noting that FRIC_COEF is only executed in the implicit dynamics analysis step, while the static general analysis step is only used to update the node coordinates and does not participate in the wear calculation. Then, the corresponding Inp file, Fortran file and CPU number are specified through the command window for simulation. The figure details the logic of the program processing incremental steps and nodes. Combining the Achard and ALE formulas, it is possible to understand from a more specific perspective how the geometric changes (volume and surface) caused by wear are reflected in the integral range and boundary conditions.

[0111] like Figure 3 As shown in the figure, the finite element model of the key parts of the high-speed train braking performance simulation test device, where: Figure 3 (a) is a simplified three-dimensional diagram of the braking system. Figure 3 (b) is the finite element model of the braking system after meshing. Figure 3 (c) Sampling points N1-N6 on the friction block surface (c); Figure 4 As shown, the evolution of wear depth of N series nodes on the wear surface of the friction block, Figure 4 (a) is a schematic diagram showing the variation of wear depth of nodes on the friction block surface over time after completion. Figure 4 (b) is a schematic diagram of the wear depth of 65Mn surface changing with time. Figure 4 (c) is a schematic diagram of the change of wear depth of 304 surface with time. Figure 4 (d) is a schematic diagram of the change of 51CR surface wear depth over time. Figure 4 (e) Schematic diagram of the wear depth of 60SM surface changing with time.

[0112] The wear changes of nodes N1-N12 along the center line of the friction block in the friction direction within 3s of the wear simulation are shown in the figure below: Figure 4 (a) shown. Figure 4 (a) shows the wear of each friction block after the simulation. The wear of the N1 node in the cut-in area of ​​the 65Mn and 304 surfaces is almost the same, but the differences in other nodes are large. The wear of the 65Mn at the N2-N12 nodes is less than that of the 304, which has the most serious eccentric wear among the four blocks. The wear of 51CR and 60SM is relatively mild and the wear is similar (the wear of 60SM is slightly less than that of 51CR); Figure 4 (b) Figure 4 (c) and Figure 4 (d) is the evolution of the wear amount at the cut-in end N1 and the cut-out end N12 of each block surface, MD is the maximum deviation between N1 and N12 at the last moment, among which 304 has the largest value and 60SM has the smallest value;

[0113] At the beginning of wear, the N1 nodes of each surface first wear, but the wear rates are different. The wear rate of the 304 surface increases significantly at 1.5s. Due to the different improvement capabilities of disc springs of different materials on the interface, the N12 nodes of 65Mn, 51CR and 60SM begin to wear at 1s, while 304 begins to wear after 1.5s and the wear amount is small, which leads to more serious eccentric wear of the 304 block.

[0114] By using the dynamic wear calculation method of the high-speed train brake pad friction block of the present invention, the dynamic characteristics are taken into account, so that the wear depth obtained by simulation is more in line with reality, which is of great significance for guiding the design and maintenance of the high-speed train brake pad friction block.

[0115] The above is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited to the above content. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for calculating dynamic wear of brake pad friction block of high-speed train, characterized in that: The steps include: Step 1: Establish the finite element model of the friction pad and brake disc; Step 2: Use finite element software ABAQUS to perform dynamics-interface wear coupling simulation solution; Step 3: Call subroutine FRIC_COEF to perform data recording and transfer analysis under implicit dynamics; Step 4: Call subroutine UMESHMOTION to perform wear analysis; Step 5: Update the grid and loop the calculation.

2. The method for calculating dynamic wear of brake pad friction block of high-speed train according to claim 1 is characterized in that: In step 1, the steps of constructing the finite element model are: Step 101: Create a three-dimensional model of the friction block and the brake disc, import the created three-dimensional model into finite element software, and assemble it; Step 102: assigning material properties; Step 103: Setting up interaction; Step 104: Set loads and mesh.

3. The method for calculating dynamic wear of the friction block of the brake pad of a high-speed train according to claim 2 is characterized in that: In step 2, in step 102, the material properties include but are not limited to density, specific heat capacity, thermal expansion coefficient, Poisson's ratio, and Young's modulus.

4. The method for calculating dynamic wear of high-speed train brake pad friction block according to claim 1 is characterized in that: In step 2, the sequential coupling method is used to solve the dynamics-interface wear coupling simulation, so that the entire simulation process is discretized into N incremental steps, and a wear calculation is performed in each incremental step.

5. The method for calculating dynamic wear of brake pad friction block of high-speed train according to claim 1, characterized in that: In step 3, the transfer analysis includes using the FRIC_COEF subroutine to receive the contact stress, contact slip and wear coefficient under implicit dynamics, and storing them in the common variable module to calculate the wear amount, specifically: The wear amount of a node in one increment is: Where: H is the material hardness of the friction block surface, is the average contact pressure of the node within 0.01s, ds i is the relative sliding distance of the node within 0.01s, k is the wear coefficient of the friction block, where, Where: V is the wear volume; F is the normal load; d is the sliding distance; The total wear depth is: Where: n is the current time step.

6. The method for calculating dynamic wear of brake pad friction block of high-speed train according to claim 5, characterized in that: In step 4, the wear effect analysis is performed by applying the calculated wear amount to the nodes of the friction block using the subroutine UMESHMOTION and the ALE algorithm; specifically, Step 401: Calculate the volume change V t : V t =V0-A·Δh(t); Where: A is the surface area affected by wear, V0 is the initial volume; Step 402: Obtain the boundary surface S after wear t : S t =S0-ΔS(Δh(t)); Where: S0 is the initial boundary surface; ΔS is the change in the boundary surface caused by wear, which is described by the wear depth and surface differential: Where: Γ is the boundary of the wear area, h is the function of wear depth over time, and is the gradient of wear depth in x and y directions; Step 403: The volume change V in step 401 and step 402 is t and the boundary surface S t Substitute into the mass conservation equation, where the mass conservation equation is: Where: x is the spatial coordinate of the grid; ρ is the material density; c = vv mesh is the relative velocity, where v is the material velocity; v mesh is the grid velocity; n0 is the external normal vector of the boundary surface; get: Where: n1 is the outer normal vector of the boundary surface under wear, v wear Indicates the relative movement speed of the wear part, n wear is the normal vector of the worn surface; v wear =vv mesh , where v is the material velocity; v mesh is the grid speed; n wear The derivation formula is as follows: n local =R T ·n global ; Where: n global is the normal vector in the global coordinate system, n local is the normal vector in the local coordinate system, R is the rotation matrix from local to global; R T is the transpose of the matrix, used to convert the global vector into a local vector; Where: N is the number of incremental steps or nodes; n global,i is the global normal vector of the ith increment or node.

7. The method for calculating dynamic wear of brake pad friction block of high-speed train according to claim 1, characterized in that: In step S5, the finite element model is updated using the ALE algorithm, and it is determined whether the calculation time has ended. If the time has not ended, the wear coupling calculation is performed; if the time has ended, the calculation is completed.

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