Design method of subway head car collision reduction mold meeting gravity criterion and posture equivalence

Abstract

The present invention discloses a method for designing a collision reduction mold of a subway lead car that meets gravity criteria and posture equivalence. The method comprises the following steps: structurally dividing the body of the subway lead car to obtain a body substructure, adjusting the material properties, geometric dimensions, and counterweight of the body substructure; simultaneously optimizing the material correction coefficient and structural dimensions; integrating the obtained static equivalent body into the subway lead car model to reduce the number of design variables and the optimization range; determining the key factors affecting the collision posture through a parameter optimization algorithm; and constructing a collision posture equivalent reduction mold model of the subway lead car. The key posture response curve of the lead car equivalent reduction mold proposed by the present invention is extremely different from the corresponding response of the full-size equivalent lead car after restoration, and the amplitude and phase difference S&G values ​​of the response corresponding to the lead car prototype are both less than 10%, with the maximum average value of MS&G=4.36%. The lead car equivalent reduction mold and the lead car prototype have good equivalence and similarity in collision posture response.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle safety testing, and in particular to a design method for a subway head car collision reduction mold that meets gravity criteria and posture equivalence. Background Art

[0002] With the rapid expansion of urban rail transit systems, ensuring passenger safety has become a top priority, requiring subway vehicles to undergo rigorous safety performance evaluation and testing during the design phase. Traditional physical crash testing is costly, time-consuming, and resource-intensive.

[0003] In recent years, the rapid development of computer-aided engineering (CAE) technology, particularly finite element analysis (FEA) and multibody dynamics simulation, has provided new avenues for researching vehicle crash safety. However, directly applying full-scale vehicle models to simulations requires significant computational resources. This also reduces the efficiency and accuracy of simulations using equivalent scaled-down models, as many factors have little influence on the overall crash response.

[0004] Therefore, the present invention is based on the equivalent reduction mold technology involving the geometric dimension scaling, material property adjustment, mass distribution optimization and equivalent conversion of dynamic characteristics of the vehicle structure. By reducing the model size while keeping the model's dynamic behavior in the collision simulation consistent with that of the prototype vehicle, the computing cost and the need for physical testing are greatly reduced while ensuring the simulation accuracy. Summary of the Invention

[0005] In view of the above problems, the present invention is proposed to provide a subway head car collision reduction mold design method that meets the gravity criterion and posture equivalence, which overcomes the above problems of low simulation efficiency and accuracy.

[0006] According to one aspect of the present invention, a method for designing a subway head car collision reduction mold that meets gravity criteria and pose equivalence is provided, comprising:

[0007] Based on the principle of static parameter equivalence, the subway car body is structurally divided into a car body substructure. The material properties, geometric dimensions, and counterweight of the car body substructure are adjusted to ensure that the equivalent model is consistent with the prototype car body in terms of mass and moment of inertia. The car body substructure includes the driver's cab and the passenger compartment area of ​​the first car.

[0008] Utilize parameter optimization technology to simultaneously optimize material correction coefficients and structural dimensions to achieve equivalent vehicle body static response.

[0009] The static equivalent car body obtained is integrated into the subway head car model, and the number of design variables and optimization range are reduced based on the optimization results.

[0010] A parameter optimization algorithm is used to determine the key factors affecting the collision posture, and then the car body and vehicle model structure that reflects the equivalence of the collision posture are determined; based on the collision dynamics characteristics, a collision posture equivalent scaled-down model of the subway head car is constructed to ensure that the posture response of the collision posture equivalent scaled-down model in the collision simulation is consistent with that of the prototype vehicle.

[0011] In an optional manner, the method further includes:

[0012] The equivalent reduction mold of the collision posture is verified by simulation methods. Specifically, the displacement cloud map, impact force timing curve, key section displacement change and dynamic response difference of the vehicle body posture of the subway head car collision reduction mold and the prototype car at different collision speeds are compared by S&G indicators to ensure that the difference indicators of all response curves are lower than the preset threshold value to verify the equivalence and similarity of the reduction mold.

[0013] In an optional manner, the driver's cab includes a plastic deformation area and an elastic deformation area;

[0014] The passenger compartment area of ​​the first car includes a chassis, side walls, a roof and end walls;

[0015] The material properties include material type, elastic modulus, and density.

[0016] In an optional manner, adjusting the material properties, geometric dimensions, and weight of the vehicle body substructure to ensure that the equivalent model is consistent with the prototype vehicle body in terms of mass and moment of inertia further includes:

[0017] By adjusting the material properties, geometric dimensions, and counterweight parameters of each vehicle body substructure, the mass and moment of inertia of each vehicle body substructure are guaranteed to be consistent with those of the corresponding parts of the prototype vehicle body. For the side walls A to D, end walls, and driver's cab, corresponding Tslide-wall or Tend-wall thickness variables are set.

[0018] In an optional manner, the synchronous optimization of the material correction coefficient and the structural dimensions using the parameter optimization technology to achieve the equivalent target of the vehicle body static response further includes:

[0019] Determining optimization objectives for equivalent static responses of the vehicle body, the optimization objectives including displacement, stress, strain indicators, and the degree of matching with the prototype vehicle body;

[0020] Determine the constraints of material correction coefficients and structural size parameters;

[0021] According to the optimization objectives and constraints, a static simulation analysis is performed using a finite element solver to obtain simulation results;

[0022] The simulation results are read through HyperStudy to calculate whether the objective function value and the constraint conditions meet the evaluation performance of the model; and the material correction coefficient and the structural size parameters are automatically adjusted to obtain the optimal parameters.

[0023] In an optional manner, integrating the obtained statically equivalent car body into the subway head car model and reducing the number of design variables and the optimization range according to the optimization results further includes:

[0024] Eliminate parameters with less impact on the response from the design variables through sensitivity analysis, and reset the optimization range of the retained optimization design variables based on the optimization results;

[0025] According to the geometric dimensions and material properties of the equivalent vehicle body structure, the search space of the design variables is limited, and the finite element model file is updated through the Tcl script language.

[0026] In an optional manner, the key factors include chassis thickness Tfloor, roof thickness Troof, elastic modulus, density and energy absorbing structure parameters.

[0027] In an optional manner, constructing a collision posture equivalent reduction model of the subway head car based on the collision dynamic characteristics and ensuring that the posture response of the collision posture equivalent reduction model in the collision simulation is consistent with that of the prototype car further includes:

[0028] Set the collision conditions of the rigid wall at different speeds and the corresponding loads and boundary conditions;

[0029] By fitting the complex relationship between the parameters of the surrogate model and the collision response, sample points are generated using the Hammersley sampling method, the fitting accuracy of different surrogate models is compared, and the best model is selected; wherein the surrogate models include RBF, RSM, and Kriging models;

[0030] The model parameters are optimized by the NSGA-II multi-objective genetic algorithm to balance the objective functions of the x-direction displacement and the z-direction displacement of the collision posture;

[0031] The accuracy and stability of the optimization results are evaluated by the Pareto analysis method, and the finite element verification calculation is performed on the Pareto frontier data to compare the error between the predicted value and the actual value;

[0032] An equivalent vehicle body collision model is constructed based on the optimized parameters, and a full-scale collision simulation is performed. The key indicators of displacement and force distribution at various collision speeds are compared between the prototype vehicle and the equivalent model, and the posture response curve is analyzed to verify whether the equivalence meets the predetermined standards.

[0033] In an optional manner, the method further includes:

[0034] By adjusting the stiffness of the suspension components, bogie parameters, and a simplified model of the energy absorption area, the posture morphology, impact force distribution, and displacement response indicators of the collision posture equivalent reduction model at different collision speeds are made highly similar to those of the prototype vehicle.

[0035] In an optional manner, the verifying the collision posture equivalent reduction mold further includes:

[0036] Establish an equivalent scaled model of the flexible vehicle body and adjust the geometric dimensions, material parameters, and counterweight mass of the model based on similarity factors to ensure that the mass distribution and stiffness characteristics are equivalent to those of the prototype vehicle;

[0037] Design an equivalent scaled model of the energy absorption area structure, and scale the geometric dimensions and force-displacement curves of the coupler, anti-climbing energy absorption structure, and cab plastic deformation zone according to the similarity factor;

[0038] Establish an equivalent scaled model of the bogie and adjust the geometric dimensions, material density, and suspension stiffness to maintain consistent dynamic response during a collision.

[0039] Perform collision simulation under multiple working conditions, adjust the collision speed to meet the scale relationship, keep non-dimensional parameters constant, and ensure the authenticity of the simulation environment;

[0040] The poses of the equivalent scale model and the prototype vehicle at different collision speeds are obtained through simulation, and then magnified and compared to verify the similarity of the poses.

[0041] Analyze the response curve, calculate and compare the impact force, displacement and body posture change curves of the equivalent scale model and the prototype vehicle;

[0042] The S&G index was used to evaluate the model response differences and ensure that the difference index of all response curves was less than 10% to verify the equivalence and similarity of the scaledown models.

[0043] According to the solution provided by the present invention, based on the principle of static parameter equivalence, the body of the subway head car is structurally divided to obtain a body substructure, and the material properties, geometric dimensions and counterweight of the body substructure are adjusted to ensure that the equivalent model is consistent with the prototype body in mass and moment of inertia; wherein, the body substructure includes a driver's cab and a passenger compartment area of ​​the head car; the material correction coefficient and the structural dimensions are simultaneously optimized using parameter optimization technology to achieve the equivalent goal of the static response of the body; the obtained statically equivalent body is integrated into the subway head car model, and the number of design variables and the optimization range are reduced according to the optimization results; the key factors affecting the collision posture are determined by the parameter optimization algorithm, and then the body and vehicle model structure that reflects the equivalence of the collision posture is determined; based on the collision dynamics characteristics, a collision posture equivalent reduction model of the subway head car is constructed to ensure that the posture response of the collision posture equivalent reduction model in the collision simulation is consistent with that of the prototype car. The key posture response curve of the lead vehicle equivalent reduction mold proposed in the present invention is extremely small after restoration, and the amplitude and phase difference S&G values ​​of the response corresponding to the lead vehicle prototype are both less than 10%, with the maximum average value MS&G = 4.36%. The lead vehicle equivalent reduction mold and the lead vehicle prototype have good equivalence and similarity in collision posture response.

[0044] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are specifically listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present invention. The same reference symbols are used throughout the drawings to represent the same components. In the drawings:

[0046] Figure 1 A schematic flow chart of a method for designing a subway head car collision reduction mold that satisfies gravity criteria and pose equivalence according to an embodiment of the present invention is shown;

[0047] Figure 2 A complete driver's cab partition diagram according to an embodiment of the present invention is shown;

[0048] Figure 3 A schematic diagram of loading conditions for static analysis of an original vehicle body according to an embodiment of the present invention is shown;

[0049] Figure 4 A schematic diagram of loading conditions for an equivalent vehicle body static analysis according to an embodiment of the present invention is shown;

[0050] Figure 5 A schematic diagram of a compressive force equivalent beam unit in the plastic deformation zone of a driver's cab according to an embodiment of the present invention is shown;

[0051] Figure 6 A schematic diagram of an equivalent simplified bogie design process according to an embodiment of the present invention is shown;

[0052] Figure 7 A schematic diagram of bogie structure modeling according to an embodiment of the present invention is shown;

[0053] Figure 8 A schematic diagram of a bogie suspension stiffness parameter optimization process according to an embodiment of the present invention is shown;

[0054] Figure 9 A schematic diagram showing the maximum lateral displacement values ​​of the frame and wheelset of an embodiment of the present invention at various collision speeds is shown;

[0055] Figure 10 A schematic diagram showing the maximum vertical lift of the wheels of a bogie at various collision speeds according to an embodiment of the present invention is shown;

[0056] Figure 11a A schematic diagram of an equivalent scaled simulation pose of a lead vehicle (magnified 10 times) according to an embodiment of the present invention is shown;

[0057] Figure 11b A schematic diagram of the simulated posture morphology of the head vehicle prototype (magnified 10 times) according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0058] Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0059] The present invention uses the equivalent similarity model design method that meets the gravity criterion as the design framework, the subway head car body description method and the collision key posture index as the design guidance, and uses the collision response equivalent static and dynamic stiffness step-by-step collaborative design technology to improve the design efficiency, and carries out the design of the equivalent similarity model of the subway head car collision posture. First, the equivalent similarity model of the flexible car body is designed: under the premise of meeting the static parameter equivalence, the material correction coefficient and the structural size parameters are optimized simultaneously to achieve the static response equivalence of the car body. Subsequently, the statically equivalent car body is placed in the head car model, and according to the static optimization results, the number and range of variables are reduced, and the collision posture equivalent car body and vehicle model are determined using the parameter optimization method. Finally, the design of the equivalent reduction mold of the head car collision posture is completed, and the equivalence and similarity of the collision posture response of the model are verified.

[0060] Figure 1 The flowchart of the design method of the subway head car collision reduction mold that meets the gravity criterion and posture equivalence of the embodiment of the present invention is shown. Figure 1 As shown, the following steps are included:

[0061] Step S101: Based on the principle of static parameter equivalence, the body of the subway head car is structurally divided to obtain a body substructure, and the material properties, geometric dimensions and counterweight of the body substructure are adjusted to ensure that the equivalent model is consistent with the prototype body in mass and moment of inertia; wherein, the body substructure includes the driver's cab and the passenger compartment area of ​​the head car.

[0062] In this embodiment, static parameter equivalence is the primary objective of the flexible vehicle body equivalent mold design, including equivalence of vehicle body mass, relative position of center of mass, and moment of inertia. When addressing this static parameter equivalence, since the vehicle body structure is regular and mostly plate-beam, the vehicle body is divided into several substructures based on structural form, force characteristics, and spatial dimensions. Material, size, and counterweight parameters are adjusted to ensure that the mass and moment of inertia of each substructure equivalent model are essentially equal to those of the corresponding prototype, while also ensuring the relative position of the substructures is equivalent, thus meeting the static parameter equivalence requirement.

[0063] Since the passenger compartment and driver's cab structures of each subway car are obviously different, the two parts are divided into substructures. Figure 2 As shown, the main structure of the passenger compartment of the lead car can be divided into four main load-bearing structures: the chassis, side walls, roof, and end walls. The chassis, roof, and end walls, because they are integral plate-like structures, can be studied as a whole during subsequent equivalent design. The side walls, because they partition the door installation space, can be divided into multiple independent plate-like structures, with the thickness and cross-sectional composition of each side wall being the same. Components such as the traction beam and bolster in the chassis are suitable for separate equivalent model design. The driver's cab is located at one end of the lead car body, connected to the chassis at the bottom and to the side walls and roof at the rear. It is mainly composed of the driver's cab frame, skin, and plate beams. In the design concept of impact-resistant subway rail vehicles, the front half of the driver's cab exhibits "weak rigidity" and may undergo plastic deformation to absorb collision energy. This is referred to as the driver's cab plastic deformation zone in this invention. The rear half maintains sufficient "strong rigidity" and generally only undergoes elastic deformation to protect the safety of the passengers. This is referred to as the driver's cab elastic deformation zone. Therefore, the driver's cab structure is spatially divided into two partitions, front and rear. The equivalence principle of the plastic deformation zone is the equivalence of the longitudinal compression force-displacement curve, and the subsequent simulation uses the equivalent simplification of beam units; the elastic deformation zone mainly constitutes the body elastic deformation zone together with the body passenger compartment zone, and the statics and collision posture equivalent design is carried out as a whole. In addition, the static parameters of the elastic deformation zone must be guaranteed to be equivalent when designing the corresponding equivalent model.

[0064] In the static simulation analysis of the vehicle body, Figure 3 As shown in the figure, three boundary conditions are established: a uniform force of 3×105N is applied to the coupler mounting seat of the first-end traction beam in the positive x direction, which is load 1; a uniform force of 1×104N is applied to the node at the front end of the traction beam in the positive z direction, which is load 2; and a full constraint of all six degrees of freedom is applied to the node at the connection between the bolster and the bogie secondary suspension spring, which is load 3. The following static calculation conditions are established for three typical car body deformation conditions: car body bending when the traction beam is subjected to longitudinal impact force, car body bending when the front end of the lead car is subjected to z-direction force, and overall bending vibration when the car body is lifted:

[0065] (1) Subcase 1, linear statics calculation condition: load 1 + load 3;

[0066] (2) Subcase 2, linear statics calculation condition: load 2 + load 3;

[0067] (3) Subcase 3, normal mode calculation condition: Use the Lanczos method EIGRL normal mode calculation to obtain the first-order vertical bending and torsion modes and corresponding frequencies of the vehicle body. The vehicle body is in a free state.

[0068] For Subcase 1, when evaluating the static calculation results, the method of describing the vehicle body's posture during collision is used. Specifically for Subcase 1, the vehicle body of the lead vehicle exhibits a significant "lower head" deformation when the coupler mounting seat is under pressure, and the vertical displacement change is significantly greater than the axial displacement change, so the The maximum value of the average vertical displacement of section S1 is used to measure the deformation degree of the vehicle body under this working condition. After selecting points and calculating, we get In Subcase 2, when the front node of the traction beam is subjected to a vertical upward force, the head vehicle body exhibits a significant "lifting" deformation, and the vertical displacement change is significantly greater than the axial displacement change. The maximum value describes the degree of deformation, The target modal frequencies in Subcase3 are 7.84 Hz and 9.90 Hz respectively.

[0069] For the vehicle material, according to the equivalent similarity model design method based on the optimization correction coefficient, the body of the entire equivalent model is assumed to be made of Q235 low carbon steel, with elastic modulus and density being E Steel and ρ Steel The elastic modulus correction factor of the material Density correction factor After correction, it is E Equ =α E E Steel, after density correction ρ Equ =α ρ ρ Steel The elastic modulus E of the equivalent vehicle body model Equ It will directly affect the stiffness of the vehicle body, thus affecting the static response and collision posture response. Therefore, the elastic modulus correction coefficient α of the equivalent vehicle body model is E Set as one of the independent variables for parameter optimization, E Equ and ρ Equ is the dependent variable.

[0070] For the chassis, the chassis of the prototype of the lead vehicle body is a hollow section plate structure. The plate thickness and cross section remain basically unchanged. Rectangular cross-section tubes covering the entire length are welded on both sides of the longitudinal direction as side beams to enhance the overall bending stiffness. The main body of the equivalent chassis structure is a homogeneous plate, and its length and width are consistent with the corresponding dimensions of the original chassis. Square tube beam structures are designed on both sides of the longitudinal direction, which makes it easy to perform static parameter equivalence and stiffness parameter equivalence with the original chassis. The plate thickness, side length and thickness of the square tube section are set as variables, defined as T floor , L floor-box and T floor-box .

[0071] For the roof, similar to the chassis, the roof of the prototype of the lead vehicle body is a hollow cross-section drum plate structure, with a full-length upper side beam structure at the connection between the two sides and the side walls. Therefore, the equivalent roof is also a main homogeneous plate structure, with a square tube beam structure arranged on both sides. The plate thickness, square tube section side length, and tube wall thickness are set as variables, defined as T roof , L roof-box and T roof-box .

[0072] For the side walls, the side wall structures on both sides are symmetrical about the longitudinal vertical plane of the vehicle body, and due to the separation of the doors, four types of substructures are formed, named: side wall panel A (2 pieces in total) and side wall panel B (2 pieces in total), side wall panel C with one window (4 pieces in total), and side wall panel D with three windows (2 pieces in total). The plate thickness and cross-section of the original side wall panel structure are basically the same. The equivalent side wall panel is designed with a homogeneous plate structure of the same length and width for each side wall panel, and window holes are left at the corresponding positions to facilitate the subsequent guarantee of equivalent quality parameters. The thickness of all equivalent side wall substructures is set as the variable T slide-wall .

[0073] For the end wall, the whole end wall is a rectangular plate structure with uniform thickness and cross-section, and a door hole in the middle. The equivalent side wall is a homogeneous plate structure with the same length and width and holes of the same size. The plate thickness is set as a variable T end-wall .

[0074] For the driver's cab, the elastic deformation zone of the equivalent driver's cab is mainly composed of a square tube beam structure and a front-end load-bearing homogeneous plate. According to the structural form and load characteristics of the driver's cab, three types of square tubes with different cross-sectional sizes are arranged: the square tube at the front is arranged obliquely, connecting the front homogeneous plate and the rear-end rectangular frame, corresponding to the streamlined structure of the front end of the driver's cab; the top square tube is arranged longitudinally, connecting the front and rear square tubes, corresponding to the roof of the driver's cab; the rear square tube connects the passenger compartment and the chassis, corresponding to the rear of the driver's cab. The front end of the equivalent driver's cab is designed with a homogeneous plate responsible for bearing the impact force of the plastic deformation zone. The thickness of the homogeneous plate and the cross-sectional dimensions (side length and wall thickness) of the front, middle and rear square tubes are set as variables T respectively. force , L cab-front 、T cab-front , L cab-mid 、T cab-mid , L cab-rear 、T cab-rear .

[0075] For sub-components such as the traction beam, the main structures welded from front to back on the prototype chassis of the head car include the front traction beam, two sets of pillow blocks, and the rear traction beam. According to the structural form and geometric dimensions of these sub-structures, the corresponding equivalent sub-structures are designed. The front and rear end follower plate seats (coupler seats) bear the crushing force from the coupler, anti-climbing energy absorption structure and the driver's cab. The corresponding equivalent panels are set to be consistent with the length and width of the original structure and have a thickness of T force The front and rear traction beams are located between the plate seat and the bolster to transmit the longitudinal impact force. The corresponding equivalent model has the same length and width and a thickness of T. tr The equivalent structure of the corbel is also set to a plate thickness of T sleeper The box-type structure consists of homogeneous plates.

[0076] According to the equivalent vehicle body structure, the corresponding static non-parametric finite element model is established. Among them, the homogeneous plate structure uses the PSHELL shell element with the unit type of CQUAD4 mesh. After the mesh size convergence analysis, in order to take into account the solution accuracy and efficiency, the mesh size is set to 100mm. The square tube beam structure uses the one-dimensional unit CBEAM with a unit size of 100mm. Each CBEAM unit is constructed between two nodes, supporting force-displacement loading analysis along the unit axis, shear force analysis of the beam section, beam bending and torsional deformation analysis, etc., which can more accurately predict the deformation and force of the beam structure under most working conditions. The cross-section type of the beam unit is BOX, that is, the square tube cross-section shape. The material card of the entire vehicle body is MAT1, and the material parameter is the variable E Equ and ρ Equ The counterweight uses the CMASS2 mass unit, with the mass value as the dependent variable. Regarding boundary conditions and calculation conditions, the equivalent vehicle body is subjected to the same loads and load steps as the static calculation of the lead vehicle body prototype.

[0077] In an optional manner, adjusting the material properties, geometric dimensions, and weight of the vehicle body substructure to ensure that the equivalent model is consistent with the prototype vehicle body in terms of mass and moment of inertia further includes:

[0078] By adjusting the material properties, geometric dimensions, and counterweight parameters of each vehicle body substructure, the mass and moment of inertia of each vehicle body substructure are guaranteed to be consistent with those of the corresponding parts of the prototype vehicle body. For the side walls A to D, end walls, and driver's cab, corresponding Tslide-wall or Tend-wall thickness variables are set.

[0079] In step S102 , parameter optimization technology is used to simultaneously optimize the material correction coefficient and the structural dimensions to achieve an equivalent target of the vehicle body static response.

[0080] Specifically, determining an optimization target for equivalent static response of the vehicle body, wherein the optimization target includes displacement, stress, strain index, and the degree of matching with the prototype vehicle body;

[0081] Determine the constraints of material correction coefficients and structural size parameters;

[0082] According to the optimization objectives and constraints, a static simulation analysis is performed using a finite element solver to obtain simulation results;

[0083] The simulation results are read through HyperStudy to calculate whether the objective function value and the constraint conditions meet the evaluation performance of the model; and the material correction coefficient and the structural size parameters are automatically adjusted to obtain the optimal parameters.

[0084] In this embodiment, since the equivalent vehicle body needs to adjust parameters to generate a large number of finite element models during the optimization design, the use of automated modeling can greatly improve the modeling efficiency. Figure 4 As shown in the figure, based on the equivalent vehicle body non-parametric static finite element model, the vehicle body material elastic modulus correction coefficient and various structural size parameters are used as variables, and the Tcl programming language is used to automatically create the MC_body.fem file suitable for Optistruct solution.

[0085] When using Tcl language for parameterized automatic modeling, the following requirements must be met:

[0086] (1) The mass, relative position of the center of mass, and moment of inertia of each substructure of the equivalent vehicle body can be made consistent with the parameters of the corresponding parts of the original vehicle body. Because the relative position of each substructure and the mass distribution trend of each substructure can be basically consistent with those of the original vehicle body when the equivalent vehicle body is designed, it is only necessary to ensure that the mass of each substructure of the equivalent vehicle body is consistent with that of the original vehicle body.

[0087] (2) The elastic modulus, density, thickness parameters of each homogeneous plate structure, and cross-sectional size parameters of the square tube structure of the equivalent vehicle body material can be parameterized and updated.

[0088] (3) It has the function of automatically judging whether the material or geometric dimensions of the established structure are reasonable. If not, the modeling and calculation can be terminated in advance and the next modeling can be automatically jumped to improve the efficiency of large-scale modeling and calculation.

[0089] According to the above requirements, the Tcl program implementation process is as follows:

[0090] Step 1: Read the material elastic modulus parameters and geometric dimension parameters, and calculate dependent variables such as material density. Code example:

[0091] set alpha_E5.00

[0092] set E_equ[expr{$alpha_E*206000}]

[0093] set rho_equ[expr{$alpha_E / 7.0*7.85e-9}]

[0094] Step 2: Import the non-parametric equivalent vehicle body finite element model file that has been built. Code example:

[0095] *feinputwithdata2"\#optistruct\\optistruct""MC_body.fem"0000011310

[0096] Step 3: Calculate the mass of each sub-structure of the existing model and the difference compared with the corresponding mass of the original vehicle body. The difference is the mass for subsequent updates.

[0097] Step 4: Determine whether the quality parameter to be updated is negative and whether the size parameter is too small or too large: if so, terminate the modeling; if not, continue modeling.

[0098] Step 5: Update the elastic modulus and mass of the material. Code example:

[0099] *setvalue mats name=$steel_truss_mat_name STATUS=11=$E_steel

[0100] Step 6: Update the size parameters of the structure. Code example:

[0101] *setvalue beamsects id=$beamsec_index beamsect_dim1=$dim_1

[0102] Step 7: Update the weight of each part. Code example:

[0103] *createmark nodes 1"by sets"$part_name

[0104] set num_nodes[llength[hm_getmark nodes 1]]

[0105] set every_node_add_mass[expr{$sum_mass / $num_nodes}]

[0106] *masselement 1$every_node_add_mass""0

[0107] *clearmark nodes 1

[0108] Step 8: Generate MC_body.fem file:

[0109] set filepath [info script]

[0110] set femfilepath[filejoin[filedir$filepath]MC_body.fem]

[0111] *feoutputwithdata$::altairOptFem$absolute_filepath.fem 00114

[0112] Use the above process to complete the Tcl program and automatically generate the corresponding finite element model by calling the hmbatch solver in HyperWorks software.

[0113] Step S103 , integrating the obtained static equivalent car body into the subway head car model, and reducing the number of design variables and the optimization range according to the optimization results.

[0114] Specifically, the parameters with little influence on the response are eliminated from the design variables through sensitivity analysis, and the optimization range of the retained optimization design variables is reset according to the optimization results;

[0115] According to the geometric dimensions and material properties of the equivalent vehicle body structure, the search space of the design variables is limited, and the finite element model file is updated through the Tcl script language.

[0116] In this embodiment, in order to make the flexible car body meet the equivalent requirements of static response, it is necessary to establish a mathematical model of the optimization problem. The static analysis of the lead car prototype includes three calculation conditions: Subcase 1 and Subcase 2 obtain the deformation of the car body under typical forces through linear static calculations, which more directly reflects the stiffness of the car body. The equivalent car body model needs to be as close as possible to the results of the lead car body prototype in the calculation of these two conditions. In addition, it is assumed that the frequency and modal vibration shape of the first-order vertical bending and torsion of the equivalent car body in the free modal calculation condition of Subcase 3 need to be kept relatively close to the original car body. The absolute value of the relative error between the results of the first two calculation conditions of the equivalent car body and the original result is calculated. and Minimum as the optimization goal; relative error value of the 7th and 8th order modal frequencies and It should be less than 10%. In addition, for the 7th and 8th order modes, the modal confidence criterion MAC is used to verify that their modal vibration shapes are the first-order vertical bending and first-order torsion of the vehicle body, respectively.

[0117] About variable α E The range needs to be determined based on the mass relationship of the equivalent car body scale model and the feasibility of plate processing. However, under the size constraints of the corresponding scale model, it is difficult to achieve the above two target masses (including counterweight) when using Q235 low carbon steel to process the model. E ≤7.

[0118] The range of structural geometric dimensional variables is primarily constrained by the dimensions of the equivalent vehicle body scale model during machining and the equivalence of the structural mass parameters of each component. Homogeneous plates and square tubes that are too small or too large are difficult to machine and difficult to control in terms of machining accuracy. Furthermore, excessively large dimensions can cause the mass of that component to exceed the set mass, failing to meet the static parameter equivalence requirements. This yields the geometric dimensional range of the equivalent vehicle body structure, as shown in Table 1.

[0119] Table 1: Equivalent variable ranges for equivalent vehicle body statics

[0120] variable unit Lower limit Upper limit <![CDATA[α E ]]> ( / ) 3.50 7.00 Tfloor (mm) 21.00 35.00 Troof (mm) 14.00 30.00 Tslide-wall (mm) 10.50 28.00 Tend-wall (mm) 10.50 49.00 Tforce (mm) 35.00 70.00 Ttr (mm) 28.00 70.00 Tsleeper (mm) 21.00 56.00 Lfloor-box (mm) 70.00 210.00 Tfloor-box (mm) 5.60 14.00 Lroof-box (mm) 70.00 210.00 Troof-box (mm) 5.60 14.00 Lcab-front (mm) 70.00 210.00 Tcab-front (mm) 5.60 14.00 Lcab-mid (mm) 70.00 210.00 Tcab-mid (mm) 5.60 14.00 Lcab-rear (mm) 70.00 210.00 Tcab-rear (mm) 5.60 14.00

[0121] In summary, the mathematical model for optimizing vehicle parameters equivalent to static response can be obtained:

[0122]

[0123] Based on the parametric finite element modeling method and optimization mathematical model of the equivalent vehicle body, an optimization-based automated equivalent modeling process is used. This process can automatically change the two variables of material elastic modulus correction coefficient and structural geometric dimensions through Hyperstudy according to the constraints such as the static parameters and dimensional parameters of the equivalent vehicle body structure. The corresponding MC_body.fem file is created using the Tcl programming language and submitted to Optistruct for solution. With the goal of approximating the static response of the lead vehicle body prototype, the flexible vehicle body structure with the optimal static response equivalence is obtained by calling the appropriate optimization algorithm. The specific implementation steps are as follows:

[0124] Step 1: Extract the static simulation calculation results of the lead vehicle body prototype in the Hyperview environment.

[0125] Step 2: Hyperstudy generates the parameter matrix of the optimization variables.

[0126] Step 3: Finite element model generation: Based on the above parameter matrix, the finite element model is automatically created using Tcl.

[0127] Step 4: Finite element solution. Call the hmbatch solver to convert the Tcl file into the MC_body.fem finite element file; use the Optistruct solver to perform calculations and analysis on the MC_body.fem file.

[0128] Step 5: Extract simulation results. Use the interface in Hyperstudy to read the MC_body.fem file and calculate the objective and constraint values ​​in the optimization model.

[0129] Step 6: Compare and judge the results. Hyperstudy evaluates the calculated objective and constraint values ​​and determines whether to generate new variables based on the optimization convergence criteria.

[0130] Step 7: Update variables or end. If convergence is not achieved, update the variables and repeat steps 2-6. If the convergence criteria are met, the iteration ends and a vehicle model that satisfies the static response equivalence is obtained.

[0131] The optimization process used a genetic algorithm. For example, the parameters were set as follows: population size 160, mutation probability 0.01, crossover rate 0.7, minimum evolutionary number 25, and maximum evolutionary number 50. After 25 generations, the optimization problem reached convergence, and the optimization process ended. The optimal values ​​of the model parameters obtained from the equivalent vehicle body statics optimization are shown in Table 2, and all the obtained parameters are within a reasonable range. The displacement contours of the equivalent vehicle body statics simulation results using this parameter matrix are similar to the deformation and mode shape contours of the lead vehicle prototype.

[0132] Table 2: Optimal values ​​of equivalent vehicle body static optimization variables

[0133] variable unit Optimal value <![CDATA[α E ]]> ( / ) 4.16 Tfloor (mm) 26.31 Troof (mm) 19.87

[0134] Furthermore, to investigate the impact of these parameters on the equivalent vehicle body stiffness and to determine the primary parameters for subsequent impact condition optimization, while eliminating secondary parameters, a DOE analysis was conducted between these parameters and the optimization objective. For the 18 variables and four objectives and constraints, the Hammersley sampling method was used to generate 1,000 sample points. This method is a type of low-discrepancy sequence and, compared to many low-discrepancy sequences, generates sample points more evenly across the variable interval, making it suitable for approximate fitting models and parameter analysis across the entire variable space.

[0135] After sending 1000 sample points into Optistruct for solution, the positive and negative effect relationships between variables and objectives and constraints are obtained and presented in the form of a Pareto plot. The Pareto plot intuitively characterizes the positive and negative effect contributions of the design variables to the response, and quantitatively ranks the contributions. The height of each bar graph represents the positive and negative contribution of the main variables to the static displacement and modal response. The shaded slope in the bar graph represents the positive and negative effect: a positive slope means that the variable has a positive effect on the response, and vice versa. Due to the large number of variables, only the top 10 variables with the greatest impact on each response are shown here. In order to measure the degree of influence of all variables on the four corresponding entities, the impact ranking of each variable in the response is first normalized between 0-1, and then the normalized impact of each variable on different responses is added and summed, and sorted in descending order. The top six parameters with the greatest impact on the overall static response of the equivalent vehicle body can be obtained: L roof-box , L floor-box , α E 、T roof 、T floor 、T slide-wall , the remaining variables have relatively little impact on the overall static response. Subsequently, these six parameters are used as optimization variables for the equivalent impact condition to perform the final parameter refinement optimization. In this embodiment, the target value and constraint value obtained by the equivalent vehicle body static strength optimization meet the equivalent requirements, the obtained elastic modulus parameters and structural dimension parameters are also within a reasonable range, and the number of parameters is reduced through the impact effect analysis. The static equivalent model can be used as an initial model for the subsequent optimization of parameters equivalent to the impact condition.

[0136] In step S104, the key factors affecting the collision posture are determined through a parameter optimization algorithm, and then the car body and vehicle model structure that reflects the equivalence of the collision posture are determined; based on the collision dynamic characteristics, an equivalent reduction model of the collision posture of the subway head car is constructed to ensure that the posture response of the equivalent reduction model of the collision posture in the collision simulation is consistent with that of the prototype vehicle.

[0137] In this embodiment, based on the principles of collision mechanics, a model including a car body, a suspension system, a bogie and an energy-absorbing structure is established using multi-body dynamics software. According to similarity theory, combined with the key parameters obtained by optimization, equivalent scaling rules for car body size, mass distribution and material properties are designed to ensure that the dynamic characteristics of the scaled-down model are consistent with those of the prototype vehicle. By comparing the posture morphology and response curves of the scaled-down model and the prototype vehicle under various collision conditions, the consistency between the two is measured using indicators such as mean square error (MSE) and correlation coefficient. According to the simulation results, for parts with large differences in posture responses, continue to adjust the energy-absorbing structure design, suspension stiffness, etc. until all indicators meet the predetermined equivalence standards. Among them, the key factors include the chassis thickness Tfloor, the roof thickness Troof, the elastic modulus, the density and the energy-absorbing structure parameters.

[0138] In an optional manner, constructing a collision posture equivalent reduction model of the subway head car based on the collision dynamic characteristics and ensuring that the posture response of the collision posture equivalent reduction model in the collision simulation is consistent with that of the prototype car further includes:

[0139] Set the collision conditions for simulating collision with a rigid wall at different speeds and the corresponding loads and boundary conditions.

[0140] The complex relationship between surrogate model fitting parameters and collision responses was investigated using the Hammersley sampling method to generate sample points. The fitting accuracy of different surrogate models, including RBF, RSM, and Kriging models, was compared to select the optimal model. The Hammersley sampling method was used to generate 1000 sample points. This method belongs to a type of low-discrepancy sequence and, compared to many low-discrepancy sequences, generates sample points more evenly across the variable interval, making it suitable for approximate fitting models and parameter analysis across the entire variable space.

[0141] The model parameters are optimized by the NSGA-II multi-objective genetic algorithm to balance the objective functions of the x-direction displacement and the z-direction displacement of the collision posture.

[0142] The accuracy and stability of the optimization results were evaluated using the Pareto analysis method. Finite element method validation calculations were performed on the Pareto frontier data to compare the error between the predicted and true values. As shown in Table 3, the model with the corresponding parameters was solved using finite element method, and the normalized sum of the area differences was calculated. The error was then compared with the corresponding Pareto results. As shown in Table 4, the overall error was generally less than 10%, with a maximum error of -9.10%, meeting the accuracy requirements and verifying the validity of the Pareto results.

[0143] Table 3: Finite element calculation results of verification points

[0144]

[0145] Table 4: Pareto validation point prediction errors

[0146]

[0147] For the Pareto results, it can be seen that overall g(ΔFkz s ) and g(ΔFtrx s ) shows an opposite trend, with g(ΔFtrx s ) increases, g(ΔFkz s ) first decreases rapidly, and then slowly decreases after a transition period. This is mainly because the points near the most convex point in the middle have a more obvious advantage in balancing the two objectives. When selecting the optimal solution from the Pareto solution set of multi-objective optimization, a variety of methods can be selected, such as the maximum bend angle selection method, the entropy weight TOPSIS method, and the normalized weighted sum selection method. The present invention adopts the normalized weighted sum selection method, which is simple to operate and has a good effect on non-absolutely smooth convex Pareto frontiers. The mathematical expression is:

[0148]

[0149] Where X is the input parameter vector in the Pareto solution set, m is the target number, ω n The target weights are both set to 0.5. Based on the calculation of 490 Pareto frontier data, the optimal solution prediction value is obtained. By verifying the accuracy of the target result prediction, the relative errors of the two optimal solutions and the true values ​​are -2.17% and 4.64% respectively. and The undamped bogie with the optimal suspension stiffness meets the equivalent simplified design requirements.

[0150] An equivalent vehicle body collision model is constructed based on the optimized parameters, and a full-scale collision simulation is performed. The key indicators of displacement and force distribution at various collision speeds are compared between the prototype vehicle and the equivalent model, and the posture response curve is analyzed to verify whether the equivalence meets the predetermined standards.

[0151] In an optional manner, the method further includes:

[0152] The equivalent reduction mold of the collision posture is verified by simulation method; among them, the displacement cloud map, impact force time series curve, key section displacement change and dynamic response difference of vehicle body posture of the subway head car collision reduction mold and prototype car at different collision speeds are compared by S&G index, ensuring that the difference index of all response curves is lower than the preset threshold value to verify the equivalence and similarity of the reduction mold. For example, the S&G criterion is used to determine the unit force (i=1,2,3,4) and frame displacement curve and (j=1,2). When the difference index is less than 10%, it proves that the substructure model is more equivalent. Under each initial velocity collision condition, the substructure model The curves are close to the prototype curves, and the amplitude difference is very small. The S&G index values ​​between the curves are all less than 10%, indicating that the outputs of the two groups of substructure models are Satisfy equivalence requirements.

[0153] In an optional manner, the method further includes:

[0154] By adjusting the stiffness of the suspension components, bogie parameters, and a simplified model of the energy absorption area, the posture morphology, impact force distribution, and displacement response indicators of the collision posture equivalent reduction model at different collision speeds are made highly similar to those of the prototype vehicle.

[0155] The equivalent simplified models of the energy-absorbing structure include the coupler, anti-climbing structure, and the cab plastic deformation zone beam element model. The first two models already exist in the finite element model of the lead vehicle prototype, while the cab plastic deformation zone beam element requires remodeling. These equivalent simplified models are constructed using the collision force equivalence method. By assigning mechanical properties to the beam elements, they reflect the plastic deformation energy absorption process of the corresponding structural prototype.

[0156] In order to obtain the beam element model of the driver's cab plastic deformation zone, the entire body structure of the first vehicle is separated to carry out finite element simulation analysis of the quasi-static compression working condition, and the longitudinal compression force-displacement curve and the distribution of the compression force in the plastic deformation zone are obtained. According to the total compression force-displacement curve and the distribution area of ​​the longitudinal crushing force in the driver's cab plastic deformation zone, the discrete beam element with the material of MAT_119 is used to replace the plastic deformation zone (such as Figure 5As shown), the beam unit is connected to the lower part of one end surface of the vehicle body, and the front end is provided with an inclined elastic-plastic material panel similar to the front end of the driver's cab.

[0157] The study of the correlation mechanism between the mass parameters, suspension stiffness and damping parameters of the bogie and the collision posture of the vehicle body shows that the damping unit force has little effect on the collision posture of the head vehicle body. Taking into account the difficulty of design, processing and precision control of the damping elements in the bogie after scaling down, as well as the poor economy, it is proposed to cancel the damping elements of the bogie and adjust the stiffness of the remaining suspension elements to obtain the design concept of an equivalent simplified bogie. In the design process, it is necessary to use an optimization method to meet the equivalence requirements. Due to the large number of suspension parameters, if the bogie parameters are changed directly in the whole vehicle collision finite element model for large-scale simulation calculations, the time cost is high and the design efficiency is low. Therefore, the substructure model of the train collision bogie is used for equivalent design. The entire process is as follows: Figure 6 shown.

[0158] Substructure methods are widely used in automotive crash simulation analysis, achieving promising results in, for example, optimizing vehicle side impact restraint systems and studying the crashworthiness of bus front trusses. The principle is to extract the primary load-bearing and deformation-prone components from the full model to form a substructure. Boundary constraints, typically displacement or velocity-time curves, are applied at the junction between the substructure and the full structure. This allows analysis and optimization to be performed using the full model, improving computational efficiency.

[0159] In a rail vehicle collision, the bogie is mainly subjected to forces and moments from the vehicle body and the track, resulting in changes in motion posture. Therefore, the bogie structure model only needs to extract the bogie and a part of the track from the head vehicle collision model. The structure is as follows Figure 7 As shown in the figure, displacement curves are applied at the connection between the bogie and the vehicle body as input to the substructure model. These displacement curves are derived from collision calculations of the lead vehicle prototype and include: ① displacement-time curves for translation and rotation in the x, y, and z directions applied to the center pin rigid body; and ② translational displacement-time curves in the x, y, and z directions applied to the upper connection nodes of the two secondary suspension springs. The mechanical responses of the front and rear bogies differ significantly, so two substructure models are constructed for each of these two bogies.

[0160] In an optional manner, the verifying the collision posture equivalent reduction mold further includes:

[0161] Establish an equivalent scaled model of the flexible vehicle body and adjust the geometric dimensions, material parameters, and counterweight mass of the model based on similarity factors to ensure that the mass distribution and stiffness characteristics are equivalent to those of the prototype vehicle;

[0162] Design an equivalent scaled model of the energy absorption area structure, and scale the geometric dimensions and force-displacement curves of the coupler, anti-climbing energy absorption structure, and cab plastic deformation zone according to the similarity factor;

[0163] Establish an equivalent scaled model of the bogie and adjust the geometric dimensions, material density, and suspension stiffness to maintain consistent dynamic response during a collision.

[0164] Perform collision simulation under multiple working conditions, adjust the collision speed to meet the scale relationship, keep non-dimensional parameters constant, and ensure the authenticity of the simulation environment;

[0165] The poses of the equivalent scale model and the prototype vehicle at different collision speeds are obtained through simulation, and then magnified and compared to verify the similarity of the poses.

[0166] Analyze the response curve, calculate and compare the impact force, displacement and body posture change curves of the equivalent scale model and the prototype vehicle;

[0167] The S&G index was used to evaluate the model response differences and ensure that the difference index of all response curves was less than 10% to verify the equivalence and similarity of the scaledown models.

[0168] In this embodiment, for the undamped bogie substructure model, the response differences of multiple collision speed conditions are comprehensively considered, and the suspension stiffness parameters are optimized and adjusted to minimize the comprehensive difference between the output responses of the two undamped bogies under different collision speed conditions and the corresponding responses of their respective initial bogie substructures. First, DOE on the suspension stiffness parameters is carried out for the front and rear bogies at each initial collision velocity; then, a proxy model is constructed based on the relationship between the parameters and the response differences, and the accuracy of the proxy model is verified; finally, a mathematical model of the optimization problem is defined, and an optimization solution is performed based on the proxy model. The entire process of bogie suspension stiffness parameter analysis and optimization is as follows: Figure 8 The maximum displacement of the frame and wheelset in the y direction of each bogie under each collision speed condition is shown in Figure 2. and and the maximum vertical lift of the wheel (j=1,2). This type of response has a weak regularity and is not suitable for establishing a proxy model for fitting. Therefore, a suitable threshold is set based on the results of the DOE, and finally the response corresponding to the optimal model is tested to see if it is within the threshold. The maximum lateral displacement of the frame and wheelset at each collision speed at the sample point in the DOE is and like Figure 9 As shown in the figure, the maximum lateral displacement values ​​of the four groups are basically kept below 10mm, indicating that the lateral movement of the frame and wheelset in the bogies with different parameters is relatively stable under various collision speeds. like Figure 10As shown, the distance between the two bogies The overall situation is at the same level, basically maintained below 20mm.

[0169] In this embodiment, the equivalent scaled finite element model of the lead vehicle is used to carry out four groups of rigid wall impact simulations, each group representing a speed level, numbered 1-4. The four speed levels correspond to the full-scale lead vehicle impact speeds of 10km / h, 15km / h, 20km / h and 25km / h. The collision speed in the full-scale model is calculated according to After scaling, the collision velocities of the scaled simulation are 1050mm / s, 1575mm / s, 2100mm / s, and 2625mm / s, respectively. The gravity acceleration remains unchanged in the simulation, as do dimensionless parameters such as the contact friction coefficient. The collision duration is 300.00ms in the full-scale lead vehicle simulation. The reduction ratio is 113.39ms. In the simulation results of the equivalent reduction mold and prototype of the lead vehicle, the vertical deformation of the vehicle posture is magnified 10 times for comparison, as shown in the figure below. Figures 11a to 11b As shown in the figure, the four collision speed conditions are numbered 1-4 respectively, and the posture of the leading vehicle at the front, middle and late stages under each collision speed is similar.

[0170] According to the solution provided by the present invention, the equivalent similarity model design method that meets the gravity criterion is used as the design framework, the key posture index of the subway head car collision is used as the equivalent similarity object, and the collision response equivalent static and dynamic stiffness step-by-step collaborative design technology is used to improve the design efficiency and complete the design of the subway head car collision posture equivalent similarity model. First, the static response equivalent similarity model of the flexible car body is designed. With the help of Tcl automated modeling, the material correction coefficient, geometric size parameters and counterweight parameters are dynamically changed during the modeling process. The optimal car body is obtained through parameter optimization. The error between its static optimization target response and the prototype response is ≤0.1%, and the maximum error between the constraint response and the corresponding response of the prototype is -8.01%. Subsequently, the static equivalent car body is placed in the head car model, and the simplified model of the energy absorption area and the equivalent simplified bogie model are updated to determine the equivalent initial model of the head car collision posture. According to the static optimization process and the results of the static response sensitivity analysis, the original 14 variables are reduced to 6, and the variable range is reduced at the same time. The collision response equivalent parameter optimization is carried out to obtain the optimal car body with collision posture equivalent. Finally, based on the optimized material correction coefficient, the similarity factor of the equivalent reduction mold is determined, and the design of the equivalent reduction mold for the collision posture of the lead vehicle is completed based on this similarity factor. The key posture response curve of the designed lead vehicle equivalent reduction mold is extremely small after restoration, and the amplitude and phase difference S&G values ​​of the response corresponding to the lead vehicle prototype are both less than 10%, and the maximum average value is M S&G=4.36%, indicating that the lead vehicle equivalent reduction mold and the lead vehicle prototype have good equivalence and similarity in terms of collision posture response, and can be used for subsequent equivalent reduction mold real vehicle processing and experimental research.

[0171] Those skilled in the art will appreciate that modules in the devices of the embodiments may be adaptively modified and deployed in one or more devices different from the embodiments. Modules, units, or components in the embodiments may be combined into a single module, unit, or component, and furthermore, they may be divided into multiple submodules, subunits, or subcomponents. All features disclosed in this specification (including the accompanying claims, abstract, and drawings), as well as all processes or units of any method or device disclosed therein, may be combined in any combination, except where at least some of such features and / or processes or units are mutually exclusive. Unless expressly stated otherwise, each feature disclosed in this specification (including the accompanying claims, abstract, and drawings) may be replaced by an alternative feature that provides the same, equivalent, or similar purpose. Furthermore, those skilled in the art will appreciate that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of the present invention and to form different embodiments. For example, in the claims below, any of the claimed embodiments may be used in any combination. The present invention may be implemented using hardware comprising a number of different elements and using a suitably programmed computer. In a unit claim that lists several means, several of these means may be embodied by the same hardware item. Unless otherwise specified, the steps in the above embodiments should not be understood as limiting the order of execution.

Claims

1. A design method for a subway head car collision reduction mold that meets gravity criteria and pose equivalence, characterized in that: include: Based on the principle of static parameter equivalence, the subway car body is structurally divided into a substructure. The material properties, geometric dimensions, and counterweight of the substructure are adjusted to ensure that the substructure is consistent with the prototype car body in terms of mass and moment of inertia. The substructure includes the driver's cab and the passenger compartment area of ​​the first car. Utilize parameter optimization technology to simultaneously optimize material correction coefficients and structural dimensions to obtain an equivalent vehicle body with respect to static dynamic response; Integrate the obtained static equivalent vehicle body into the vehicle body substructure, and reduce the number of design variables and optimization range based on the optimization results; The key factors affecting the collision posture are determined through a parameter optimization algorithm, and then the equivalent reduction model of the collision posture is determined; based on the collision dynamic characteristics, an equivalent reduction model of the collision posture of the subway head car is constructed to ensure that the posture response of the equivalent reduction model of the collision posture in the collision simulation is consistent with that of the prototype car.

2. The design method for a subway head car collision reduction mold that meets the gravity criterion and pose equivalence according to claim 1 is characterized in that: The method further comprises: The collision posture equivalent reduction model is verified by simulation methods. The S&G indicators are used to compare the displacement cloud maps, impact force timing curves, key section displacement changes, and dynamic response differences of the collision posture equivalent reduction model and the prototype vehicle at different collision speeds to ensure that the difference indicators of all response curves are lower than the preset threshold value, so as to verify the equivalence and similarity of the collision posture equivalent reduction model.

3. The design method for a subway head car collision reduction mold that meets the gravity criterion and pose equivalence according to claim 1 or 2, characterized in that: The driver's cab includes a plastic deformation area and an elastic deformation area; The passenger compartment area of ​​the first car includes a chassis, side walls, a roof and end walls; The material properties include material type, elastic modulus, and density.

4. The design method for a subway head car collision reduction mold that meets the gravity criterion and pose equivalence according to claim 1 is characterized in that: The adjusting of the material properties, geometric dimensions and weight of the vehicle body substructure to ensure that the vehicle body substructure is consistent with the prototype vehicle body in terms of mass and moment of inertia further includes: By adjusting the material properties, geometric dimensions, and counterweight parameters of each carbody substructure, the mass and moment of inertia of each carbody substructure are guaranteed to be consistent with the corresponding parts of the prototype carbody. For the sidewall panels A to D, end walls, and driver's cab, the corresponding Tslide-wall or Tend-wall thickness variables are set. The side wall structure is symmetrical about the longitudinal vertical plane of the vehicle body. Due to the separation of the doors, four types of substructures are formed, named: side wall panel A, side wall panel B, side wall panel C with one window, and side wall panel D with three windows.

5. The design method of subway head car collision reduction mold that meets gravity criteria and pose equivalence according to claim 1 is characterized in that: The method of using parameter optimization technology to simultaneously optimize the material correction coefficient and the structural dimensions to obtain an equivalent vehicle body with a static response further includes: Determining optimization objectives for equivalent static responses of the vehicle body, the optimization objectives including displacement, stress, strain indicators, and the degree of matching with the prototype vehicle body; Determine the constraints of material correction coefficients and structural size parameters; According to the optimization objectives and constraints, a static simulation analysis is performed using a finite element solver to obtain simulation results; The simulation results are read through HyperStudy to calculate whether the objective function value and the constraint conditions meet the evaluation performance of the model; and the material correction coefficient and the structural size parameters are automatically adjusted to obtain the optimal parameters.

6. The design method of subway head car collision reduction mold that meets gravity criteria and pose equivalence according to claim 1 is characterized in that: The step of integrating the obtained statically equivalent vehicle body into the vehicle body substructure and reducing the number of design variables and the optimization range according to the optimization results further includes: Eliminate parameters with less impact on the response from the design variables through sensitivity analysis, and reset the optimization range of the retained optimization design variables based on the optimization results; According to the geometric dimensions and material properties of the equivalent vehicle body structure, the search space of the design variables is limited, and the finite element model file is updated through the Tcl script language.

7. The design method of subway head car collision reduction mold that meets gravity criterion and posture equivalence according to claim 1 is characterized in that: The key factors include chassis thickness Tfloor, roof thickness Troof, elastic modulus, density and energy absorbing structure parameters.

8. The design method for a subway head car collision reduction mold that meets the gravity criterion and pose equivalence according to claim 6 is characterized in that: The step of constructing a collision posture equivalent reduction model of the subway head vehicle based on the collision dynamic characteristics and ensuring that the posture response of the collision posture equivalent reduction model in the collision simulation is consistent with that of the prototype vehicle further includes: Set the collision conditions of the rigid wall at different speeds and the corresponding loads and boundary conditions; By fitting the complex relationship between the parameters of the surrogate model and the collision response, sample points are generated using the Hammersley sampling method, the fitting accuracy of different surrogate models is compared, and the best model is selected; wherein the surrogate models include RBF, RSM, and Kriging models; The model parameters were optimized using the NSGA-II multi-objective genetic algorithm to balance the objective functions of the x-direction displacement and the z-direction displacement of the collision posture; the x-direction is the horizontal direction of the subway model, and the z-direction is the vertical direction perpendicular to the horizontal direction of the subway model. The accuracy and stability of the optimization results are evaluated by the Pareto analysis method, and the finite element verification calculation is performed on the Pareto frontier data to compare the error between the predicted value and the actual value; Based on the optimized parameters, a collision posture equivalent reduction model is constructed, and a full-scale collision simulation is performed. The key indicators of displacement and force distribution of the prototype vehicle and the collision posture equivalent reduction model at various collision speeds are compared, and the posture response curve is analyzed to verify whether the equivalence meets the predetermined standards.

9. The design method of subway head car collision reduction mold that meets gravity criterion and posture equivalence according to claim 1 is characterized in that: The method further comprises: By adjusting the stiffness of the suspension components, bogie parameters, and a simplified model of the energy absorption area, the posture morphology, impact force distribution, and displacement response indicators of the collision posture equivalent mold at different collision speeds are made highly similar to those of the prototype vehicle.

10. The design method of subway head car collision reduction mold that meets gravity criterion and posture equivalence according to claim 2 is characterized in that: The verification of the equivalent reduction mold of the collision posture further includes: Establish the vehicle body substructure and adjust the model's geometric dimensions, material parameters, and counterweight mass based on similarity factors to ensure that the mass distribution and stiffness characteristics are equivalent to those of the prototype vehicle. Design an equivalent scaled model of the energy absorption area structure, and scale the geometric dimensions and force-displacement curves of the coupler, anti-climbing energy absorption structure, and cab plastic deformation zone according to the similarity factor; Establish an equivalent scaled model of the bogie and adjust the geometric dimensions, material density, and suspension stiffness to maintain consistent dynamic response during a collision. Perform collision simulation under multiple working conditions, adjust the collision speed to meet the scale relationship, keep non-dimensional parameters constant, and ensure the authenticity of the simulation environment; Through simulation, the equivalent collision posture model and the prototype vehicle's posture at different collision speeds are obtained, and then magnified and compared to verify the similarity of the postures. Analyze the response curve, calculate and compare the impact force, displacement and body posture change curves of the equivalent scale model and the prototype vehicle in the collision posture; The S&G index is used to evaluate the model response difference to ensure that the difference index of all response curves is less than 10% to verify the equivalence and similarity of the equivalent reduction mold of the collision posture.

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