A method for modeling the dynamics of a plastic hinge of a train coupler draft gear

Abstract

This invention discloses a method for modeling the plastic hinge dynamics of a train coupler device, relating to the field of rail transit vehicle collision safety technology. The method includes: establishing a structural discretization criterion; identifying failure modes of the coupler device under different collision conditions, extracting key mechanical parameters, generating a master list of plastic hinges, and obtaining benchmark simulation data for model verification; based on the discretization criterion and the master list of plastic hinges, discretizing the coupler device into a multi-body system topology consisting of several rigid bodies connected by kinematic pairs; simulating plastic deformation and fracture behavior based on the multi-body system topology; assembling and solving the system dynamic equations to obtain the dynamic response of the coupler device during the collision process and determining the simulation results; and verifying the accuracy of the multi-body dynamics model and evaluating computational efficiency by comparing the simulation results with the benchmark simulation data. This invention significantly improves the depth of collision safety assessment.

Description

Technical Field

[0001] This invention relates to the field of collision safety technology for rail transit vehicles, and in particular to a method for modeling the dynamics of the plastic hinge of a train coupler device. Background Technology

[0002] Train collision safety is a major issue in the field of rail transit. As a core component connecting vehicles and transmitting impact forces, the dynamic response of the coupler and buffer directly affects the train's collision safety performance. In actual collisions, the semi-permanent coupler and buffer of high-speed trains is highly susceptible to bending instability or even fracture failure. This non-ideal failure mode is one of the key factors inducing catastrophic consequences such as train derailment and overtaking. Therefore, constructing a collision simulation model that can accurately simulate the dynamic behavior of the coupler and buffer while also considering computational efficiency is of great significance for train collision safety design and assessment.

[0003] Currently, collision simulation modeling methods for hook-and-buffer devices are mainly divided into two categories, but both have obvious limitations: (1) Fine simulation model based on finite element method: This method establishes a detailed three-dimensional geometric model of the hook and buffer device and uses a fine mesh to simulate its complex physical processes such as elastic-plastic deformation, contact and failure, which can accurately reflect the plastic deformation mechanism and stress distribution of the structure. However, the train system has a huge number of degrees of freedom. Establishing a fine finite element model at the whole train level usually involves millions or even tens of millions of mesh elements, which makes a single simulation take several days or even weeks. The computational efficiency is extremely low and it is difficult to apply it to the rapid safety assessment and parametric analysis of the whole vehicle system.

[0004] (2) Simplified simulation model based on multibody dynamics: This method simplifies the vehicle structure into a rigid or flexible body and equates the coupler and buffer device to a one-dimensional spring-damped unit with nonlinear force-displacement characteristics. Its advantages are simple model and fast solution speed, which can complete the whole vehicle collision dynamics simulation in minutes to hours, and is suitable for macroscopic motion response analysis at the train system level. However, this model usually only considers the axial crushing energy absorption behavior of the coupler and buffer device, and cannot simulate the non-ideal failure modes such as bending instability and fracture failure that occur in the collision. This results in significant deviations between the simulation results and the derailment, climbing and other forms that occur in real accidents, which seriously limits its practical application value in safety optimization and strategy formulation.

[0005] In summary, existing modeling methods struggle to balance accuracy and efficiency: the finite element method, while highly accurate, incurs enormous computational costs, failing to meet the demands of rapid system-level analysis; while multibody dynamics methods offer efficient solutions, their simulation accuracy is limited due to insufficient physical representation capabilities. This contradiction hinders train collision safety, particularly in the research and protective design of complex accident scenarios caused by the instability of the coupling and buffer mechanism. Therefore, developing a novel dynamic modeling method that accurately reflects the non-ideal failure modes of the coupling and buffer mechanism while possessing high computational efficiency has become a critical technical problem urgently needing to be solved in this field. Summary of the Invention

[0006] The technical problem to be solved by this invention is to overcome the shortcomings of low computational efficiency of existing finite element models and insufficient physical representation ability of multibody dynamics models, and to propose a dynamic modeling method for the plastic hinge of a train coupler device.

[0007] To achieve the above objectives, the present invention provides a method for dynamic modeling of the plastic hinge of a train coupler and buffer device, comprising: Establish a structural discretization criterion, based on the geometric configuration and expected deformation region of the train coupler device, to determine the criteria for discretizing a continuous structure into several rigid body components and plastic hinge connection points; The failure modes of the hook-and-buffer device under different collision conditions are identified, and key mechanical parameters for defining the plastic hinge are extracted to generate a master list of plastic hinges. At the same time, benchmark simulation data for model verification are obtained. Based on the discretization criterion and the plastic hinge master list, the hook and buffer device is discretized into a multi-body system topology structure consisting of several rigid bodies connected by kinematic pairs. Based on the multibody system topology, inertial parameters are defined for each rigid body, including mass, center of mass position and moment of inertia. The corresponding kinematic pairs in the multibody system topology are given mechanical properties including nonlinear constitutive relations and failure criteria. Plastic deformation and fracture behavior are simulated to establish the multibody dynamics model of the hook and buffer device. Based on the multibody dynamics model, the system dynamics equations are assembled and solved to obtain the dynamic response of the hook buffer device during the collision process and determine the simulation results. The accuracy of the multibody dynamics model is verified and the computational efficiency is evaluated by comparing the simulation results with the benchmark simulation data.

[0008] Preferably, the structural discretization criterion includes: Criterion 1: Divide the structure at locations where there is a specified relative motion in the structural design; Criterion 2: Delineate at potential areas of plastic hinge, yield, or fracture; Criterion 3: Under the premise of satisfying Criterion 1 and Criterion 2, large-sized components with no risk of failure should be simplified as a whole.

[0009] Preferably, the failure modes of the hook-and-response device under different collision conditions are identified, and key mechanical parameters for defining the plastic hinge are extracted to generate a master list of plastic hinges, including: The dynamic response of the hook and buffer device under different collision conditions was analyzed by finite element simulation to identify local plastic deformation regions. The identified local plastic deformation regions are abstracted as plastic hinges. The type, spatial location, and critical load of the plastic hinges are extracted. A master list of plastic hinges is generated through equivalent merging and contribution filtering.

[0010] Preferably, the main list of plastic hinges is generated through equivalent merging and contribution filtering, including: Establish an initial list of plastic hinges, compiling all plastic hinges identified under all collision conditions, along with their corresponding types, spatial locations, and critical load parameters; The plastic hinges in the initial list of plastic hinges are judged for spatial proximity and mechanical mode consistency. Several plastic hinges with spatial distance within the preset range of structural feature size and the same or similar mechanical mode are merged into an equivalent plastic hinge. The critical load is taken as the minimum value among the merged plastic hinges. Based on the principles of energy absorption contribution rate and deformation dominance, minor plastic hinges with negligible impact on the overall mechanical response are eliminated. The elimination criteria are: the average energy absorption contribution rate of the plastic hinge is lower than the preset range, and the failure does not dominate the overall deformation mode. The plastic hinges that are ultimately retained are globally sequentially numbered to form a master list of plastic hinges containing each type of plastic hinge, three-dimensional coordinates, and critical load.

[0011] Preferably, the type of kinematic pair includes ball joints, universal joints, cylindrical joints, and translational joints.

[0012] Preferably, the mechanical properties include: The characteristics of free rotation at extreme angles and limiting impact of rotating structures; The nonlinear force-displacement constitutive relationship of the axial crushing energy absorption component; The moment-rotation constitutive relationship and failure criterion for bending plastic hinges.

[0013] Preferably, based on the multibody dynamics model, assembling and solving the system dynamic equations includes: Based on the rigid body partitioning, inertial parameters, kinematic pair topology, and plastic hinge mechanical properties, corresponding rigid bodies, kinematic pairs, and force elements are created and integrated into a complete multibody dynamics model. Set up state monitoring and switching logic for each plastic hinge. When the plastic deformation of the hinge reaches the preset failure criterion, automatically trigger the locking of the degree of freedom of the corresponding kinematic pair or remove it from the system connection relationship. Perform static equilibrium analysis on the integrated system, calculate and verify the total degrees of freedom of the system; By applying collision loads and boundary conditions, the dynamic equations of the system are solved by numerical integration to obtain the dynamic response of the hook and buffer device during the collision process.

[0014] Preferably, verifying the accuracy of the multibody dynamics model includes at least one of energy absorption sequence verification, failure mode verification, and dynamic response verification.

[0015] Compared with the prior art, the present invention has the following advantages and technical effects: (1) The model constructed in this invention has a computational scale much smaller than that of a nonlinear finite element model of equivalent precision. The finite element method requires dividing a large number of meshes and calculating the stress and strain of each element, while this invention describes the system through discrete rigid bodies and concentrated plastic hinges, significantly reducing the order of magnitude of the degrees of freedom of the dynamic equations. This method can achieve an order-of-magnitude acceleration in computation, making it possible to conduct a large number of parameter studies, working condition screening, and optimization design within the engineering development cycle.

[0016] (2) Traditional multibody dynamics models treat structures as rigid or ideal elastic bodies, failing to predict bending and fracture during collisions. This invention systematically identifies and quantifies key failure modes and plastic hinge parameters, and endows kinematic pairs with precise mechanical properties including plastic deformation stages and failure criteria. This enables the model to dynamically predict the sequential triggering of plastic hinges, the progressive crushing of the structure, and the eventual breakage and separation of components due to excessive rotation angles, significantly improving the depth of collision safety assessment. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a flowchart of a method for modeling the dynamics of a plastic hinge in a train coupler device according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the plastic hinge dynamic model of the train coupler device constructed according to an embodiment of the present invention. Detailed Implementation

[0018] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0019] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0020] like Figures 1-2 As shown, this embodiment proposes a method for modeling the plastic hinge dynamics of a train coupler and buffer device, including: Establish a structural discretization criterion, based on the geometric configuration and expected deformation region of the train coupler device, to determine the criteria for discretizing a continuous structure into several rigid body components and plastic hinge connection points; The failure modes of the hook-and-buffer device under different collision conditions are identified, and key mechanical parameters for defining the plastic hinge are extracted to generate a master list of plastic hinges. At the same time, benchmark simulation data for model verification are obtained. Based on the discretization criterion and the plastic hinge master list, the hook and buffer device is discretized into a multi-body system topology structure consisting of several rigid bodies connected by kinematic pairs. Based on the multibody system topology, inertial parameters are defined for each rigid body, including mass, center of mass position and moment of inertia. The corresponding kinematic pairs in the multibody system topology are given mechanical properties including nonlinear constitutive relations and failure criteria. Plastic deformation and fracture behavior are simulated to establish the multibody dynamics model of the hook and buffer device. Based on the multibody dynamics model, the system dynamics equations are assembled and solved to obtain the dynamic response of the hook buffer device during the collision process and determine the simulation results. By comparing the simulation results with the baseline simulation data, the accuracy of the multibody dynamics model is verified and the computational efficiency is evaluated.

[0021] Furthermore, the structural discretization criterion includes: Criterion 1: Divide the structure at locations where there is a specified relative motion in the structural design; Criterion 2: Delineate at potential areas of plastic hinge, yield, or fracture; Criterion 3: Under the premise of satisfying Criterion 1 and Criterion 2, large-sized components with no risk of failure should be simplified as a whole.

[0022] Specifically, the establishment of the structural discretization criterion aims to establish the basic principle of discretizing the continuous hook and buffer device structure into several rigid bodies, providing a clear theoretical basis for the division of rigid bodies in subsequent steps.

[0023] Specifically, the following three principles should be followed: Criterion 1: Classification based on the inherent motion behavior of the system: Classification is made at locations where there is a specified relative motion in the structural design (such as bearings, ball joints, etc.). This criterion aims to reproduce the inherent kinematic relationship of the device, such as the head-shaking or head-nodding motion of the hook and buffer device relative to the mounting base. Criterion 2: Classification based on structural collision deformation failure: Through theoretical analysis or finite element simulation, classification is made at potential regions of plastic hinges, yielding, or fracture (such as structural discontinuities or high-stress areas). This criterion is a prerequisite for subsequently introducing plastic hinges to simulate nonlinear failure modes such as local bending instability and fracture in structures. Criterion 3: Modeling Simplification Criterion: Under the premise of satisfying the above criteria, the geometric structure is reasonably simplified, and large-sized components with no internal failure risk are regarded as a rigid body to optimize model complexity and balance computational accuracy and solution efficiency.

[0024] Furthermore, the failure modes of the hook-and-response device under different collision conditions are identified, and key mechanical parameters for defining the plastic hinge are extracted to generate a master list of plastic hinges, including: The dynamic response of the hook and buffer device under different collision conditions was analyzed by finite element simulation to identify local plastic deformation regions. The identified local plastic deformation regions are abstracted as plastic hinges. The type, spatial location, and critical load of the plastic hinges are extracted. A master list of plastic hinges is generated through equivalent merging and contribution filtering.

[0025] Specifically, this step uses finite element simulation to identify and quantify the failure modes of the hook-and-buffer device under various typical collision conditions, and extracts key plastic hinge parameters to provide a basis for subsequent plastic hinge dynamic modeling. The specific implementation process is as follows: Multi-condition collision finite element simulation analysis: High-precision collision finite element models are established and simulated for typical collision scenarios that the hook and buffer device may encounter during operation. Specifically, this includes: Test condition design: Based on actual operating conditions and design specifications, key variables such as initial speed, vehicle mass, and eccentricity distance are selected to design a simulation scheme covering typical conditions such as center-of-field collision and lateral / vertical eccentric collision.

[0026] Simulation modeling and solution: In explicit dynamic analysis software (Abaqus or LS-DYNA), a finite element model containing an accurate material model, contact definition and connection relationship is established. Loads and constraints are applied according to the working conditions defined in the experimental working conditions, and dynamic collision simulation is performed.

[0027] Failure Mode Identification: Post-processing of simulation results is performed, and the main local plastic deformation regions under each working condition are identified by analyzing energy absorption history, plastic strain cloud map, stress distribution and structural deformation animation.

[0028] Plastic hinge parameter extraction: The identified local plastic deformation regions are abstracted and defined as plastic hinges, and the following key parameters are extracted for each plastic hinge: Types: Based on the dominant deformation mode, they are classified as axial crushing, transverse bending, vertical bending, and fracture failure. Spatial location: The center point of the plastic hinge is identified using three-dimensional coordinates (relative to the origin of the global coordinate system); Critical load: The critical force or critical bending moment that triggers significant plastic deformation or failure of the plastic hinge.

[0029] Furthermore, through equivalent merging and contribution filtering, the main list of plastic hinges is generated, including: Establish an initial list of plastic hinges, compiling all plastic hinges identified under all collision conditions, along with their corresponding types, spatial locations, and critical load parameters; The plastic hinges in the initial list of plastic hinges are judged for spatial proximity and mechanical mode consistency. Several plastic hinges with spatial distance within the preset range of structural feature size and the same or similar mechanical mode are merged into an equivalent plastic hinge. The critical load is taken as the minimum value among the merged plastic hinges. Based on the principles of energy absorption contribution rate and deformation dominance, minor plastic hinges with negligible impact on the overall mechanical response are eliminated. The elimination criteria are: the average energy absorption contribution rate of the plastic hinge is lower than the preset range, and the failure does not dominate the overall deformation mode. The plastic hinges that are ultimately retained are globally sequentially numbered to form a master list of plastic hinges containing each type of plastic hinge, three-dimensional coordinates, and critical load.

[0030] Specifically, a master list of plastic hinges is generated, including: Data compilation: Establish an initial list of plastic hinges, and compile the plastic hinges identified under all working conditions and their parameters (type, location, critical load).

[0031] Equivalent merging: Spatial and mechanical consistency is judged for plastic hinges in the initial list. If the spatial distance between two or more plastic hinges is within 5% of the structural feature dimension and the mechanical modes are the same or highly similar, they are merged into one equivalent plastic hinge; its critical load is taken as the minimum value among all relevant working conditions to ensure the robustness of the model.

[0032] Contribution screening: Based on the principles of energy absorption contribution rate and deformation dominance, minor plastic hinges with negligible impact on the overall mechanical response are eliminated. Specifically, if the average energy absorption contribution rate of a plastic hinge is less than 5%, and its failure does not dominate the overall deformation mode, it is eliminated, thereby optimizing model complexity while ensuring accuracy.

[0033] Generate a master list of plastic hinges: Based on the final result after integration and simplification, globally sequentially number the plastic hinges that are ultimately retained (e.g., ...). , ,... (This section clarifies the type, three-dimensional coordinates, and critical load of the load.)

[0034] Furthermore, the types of kinematic pairs include ball joints, universal joints, cylindrical joints, and translational joints.

[0035] Specifically, based on the established discretization criteria and the master list of plastic hinges, the continuous hook-and-restraint device structure is discretized into a system topology model consisting of multiple rigid bodies connected by kinematic pairs. The specific implementation process is as follows: Rigid body partitioning: Based on the discretization criteria and the analysis results of the master list of plastic hinges, rigid body partitioning is performed. The specific implementation process is as follows: Partitioning based on inherent kinematic pairs: Create rigid body boundaries at the defined locations of inherent kinematic pairs (such as the ball joint connection between the coupler and the mounting base) to ensure that the partitioned model can accurately reproduce the degrees of freedom allowed by the structural design.

[0036] Based on the division of predicted failure locations: each plastic hinge location is set as a rigid body boundary, so that each plastic hinge connects two independent rigid bodies, providing a geometric basis for defining nonlinear mechanical behavior at the corresponding locations.

[0037] Based on model simplification: For continuous structures that are not divided, have no expected internal failures, and have a uniform mass distribution, they are defined as a rigid body to control the total number of degrees of freedom of the model.

[0038] Rigid body numbering and range definition: Based on the partitioning results, each rigid body is sequentially numbered (e.g., ...). , ,... (and its geometric range is described in detail based on the three-dimensional geometric model).

[0039] Kinematic pair definition: Based on a defined rigid body partitioning scheme, define the types of kinematic pairs connecting the rigid bodies to complete the system's kinematic topology construction. The specific implementation process is as follows: Kinematic pair type determination and definition: Based on the actual function and geometric constraints between adjacent rigid bodies, assign a suitable kinematic pair type to each pair of rigid bodies with a connection relationship, including but not limited to: ball joint (allowing 3 rotational degrees of freedom), universal joint (allowing 2 rotational degrees of freedom), cylindrical joint (allowing 1 rotational and 1 translational degree of freedom), and translational joint (allowing 1 translational degree of freedom).

[0040] System motion relationship table construction: Define the number of each motion pair ( , ,... The rigid bodies connected, the types of kinematic pairs, and the allowed degrees of freedom form a table of system motion relationships.

[0041] System kinematic consistency verification: Calculate the total degrees of freedom of the system to ensure that there are no over-constraints or under-constraints in the system, and guarantee the rationality and solvability of the model's kinematic behavior.

[0042] Furthermore, based on the rigid body partitioning scheme, the inertial parameters of each rigid body in the system are obtained through the centroid and mass property analysis functions of CAD / CAE software. This provides necessary parameters for the subsequent establishment of dynamic equations. In this embodiment, the inertial parameters mainly include: m The mass of a rigid body; ( x , y , z ): The center of mass of the rigid body is located at the lower edge of the global coordinate system. x , y , z Coordinate components along the axial direction; Ixx , Iyy , Izz Rigid body relative to global coordinate system x , y , z Moment of inertia of the shaft; Geometric parameters (such as size and shape).

[0043] Furthermore, the mechanical properties include: The characteristics of free rotation at extreme angles and limiting impact of rotating structures; The nonlinear force-displacement constitutive relationship of the axial crushing energy absorption component; The moment-rotation constitutive relationship and failure criterion for bending plastic hinges.

[0044] Specifically, based on the definition of motion relationships, precise mechanical constitutive relations and failure criteria are assigned to the key kinematic pairs to simulate plastic deformation and fracture failure behavior. The specific process is as follows: Definition of mechanical characteristics of rotating mechanisms: For rotating structures that simulate rigid body rotation such as head-shaking and head-nodding of couplers, the free rotation and limit impact characteristics within the limit angle are defined.

[0045] Within the design angle range of the vehicle's coupled state, since the hook and buffer device lacks an automatic centering function, its rotational torque is approximately zero. , When the rotation angle exceeds the design limit, the kinematic pair will touch the mechanical limit, and the torque will exhibit rigid impact. This mechanical characteristic can be characterized by the following mathematical model: ; ; In the formula, and These are the torques about the y-axis (nodding motion) and z-axis (head shaking motion), respectively. , These are the relative rotation angles around the y-axis and z-axis, respectively; , These are the extreme angles for nodding and shaking the head, respectively. 、 The equivalent stiffness of the limiting impact in the nodding and shaking directions are respectively.

[0046] Constitutive relation definition of axial crushing energy absorption component: For translational hinges simulating the axial crushing behavior of components such as crushing tubes and buffers, based on experimental data or finite element simulation results, its nonlinear force-displacement relationship is defined. Constitutive relation: Characteristics of the gas-liquid buffer: Its mechanical behavior exhibits nonlinear damping characteristics related to displacement and velocity. The experimental curve can be simplified and fitted using a piecewise linear function, and the mathematical expression is as follows: ; In the formula, The axial resistance force of the buffer is related to the displacement. and speed Related; The axial resistance loading and unloading curves for the compression and tension processes of the buffer are shown respectively. This refers to the axial relative displacement between the two ends of the gas-liquid buffer. The axial relative velocity between the two ends of the gas-liquid buffer; This is the maximum compression stroke of the gas-liquid buffer.

[0047] Mechanical characteristics of energy-absorbing tubes: The mechanical behavior of energy-absorbing tubes is mainly characterized by progressive crushing under axial compression. Their force-displacement curves typically contain three typical stages, which can be characterized by the following piecewise functions: ; In the formula, This refers to the crushing force of the energy-absorbing tube during axial compression. This refers to the axial relative displacement between the two ends of the energy-absorbing tube. The initial elastic stiffness of the energy-absorbing tube; This represents the limit displacement during the elastic phase of the energy absorber. For the plastic crushing platform force of the energy-absorbing tube; This represents the displacement at the end of the plastic plateau stage of the energy absorber. This is the equivalent stiffness of the energy absorber after it enters the densification stage.

[0048] Bending plastic hinge constitutive relation definition: For predicted rotational hinges (such as cylindrical hinges and universal hinges) used to simulate structural bending instability, the torque-rotation angle is defined for the entire process from elasticity and plasticity to failure. The constitutive relation, represented by a piecewise function, has the following general form: ; In the formula, For bending plastic hinges at an angle of The bending moment it bears; For the elastic stage rotational stiffness of a bending plastic hinge; The yield angle at which a flexural plastic hinge enters the yielding stage; Tangential stiffness during the plastic stage; This is the critical angle at which the plastic hinge fails. This is a sign function used to distinguish between forward and reverse bending.

[0049] When the plastic rotation angle of the hinge exceeds the critical rotation angle at which the plastic hinge fails. When a hinge fails, it is determined to be faulty. During the solution process, when a hinge is detected to meet its preset failure criteria, the constraint properties of that hinge are immediately modified. Specifically, all degrees of freedom of the failed hinge are locked, or it is directly removed from the multibody system, thereby simulating the fracture of the structure at that point and its dynamic separation from the adjacent vehicle body.

[0050] Furthermore, based on the aforementioned multibody dynamics model, the system dynamic equations are assembled and solved, including: Based on the rigid body partitioning, inertial parameters, kinematic pair topology, and plastic hinge mechanical properties, corresponding rigid bodies, kinematic pairs, and force elements are created and integrated into a complete multibody dynamics model. Set up state monitoring and switching logic for each plastic hinge. When the plastic deformation of the hinge reaches the preset failure criterion, automatically trigger the locking of the degree of freedom of the corresponding kinematic pair or remove it from the system connection relationship. Perform static equilibrium analysis on the integrated system, calculate and verify the total degrees of freedom of the system; By applying collision loads and boundary conditions, the dynamic equations of the system are solved by numerical integration to obtain the dynamic response of the hook and buffer device during the collision process.

[0051] Specifically, in multibody dynamics software (such as ADAMS or SIMPACK), model components are created one by one according to the aforementioned steps and integrated into the system to construct a complete and solvable dynamic model of the plastic hinge of the hook-and-buffer device. The main implementation steps are as follows: Rigid body import and attribute assignment: Based on the rigid body's properties, create each rigid body in the software (e.g., ...). , ,... It accurately assigns mass, center of mass position, and moment of inertia to the object. Simultaneously, it associates or creates the object's geometry for visualization and contact definition.

[0052] Establishment of kinematic pairs and force elements: Based on the system topology, kinematic pairs are created between the corresponding rigid bodies. , ,... Subsequently, based on the multibody system topology, precise nonlinear mechanical properties are assigned to the specified kinematic pairs, and force elements such as plastic hinges are created.

[0053] Failure Criterion Implementation: Based on the defined failure criteria, monitoring and state switching logic is written in the software for each plastic hinge using a built-in scripting language (such as ADAMS' ViewCommander script) or by utilizing state variables and sensor functions. This logic is implemented when the criterion (such as plastic rotation angle) is met. When the condition is met, the hinge degree of freedom is locked or removed from the system.

[0054] System Initialization and Verification: The integrated complete system is initialized and verified. First, a static equilibrium analysis is run under a gravity field to verify whether the model remains stable under no external loads, ensuring there are no unreasonable initial internal forces. Then, the total number of degrees of freedom of the system is calculated and verified to confirm its consistency with the theoretical value based on kinematic chain predictions, eliminating over-constraints or under-constraints, and ensuring the solvability of the model. Finally, collision loads are applied, and the system dynamics are solved.

[0055] Furthermore, verifying the accuracy of the multibody dynamics model includes at least one of energy absorption sequence verification, failure mode verification, and dynamic response verification.

[0056] Specifically, the model calculation accuracy verification aims to verify the accuracy, robustness, and computational efficiency of the established model through rigorous dynamic operating conditions, ensuring that it meets the requirements of engineering applications. The specific process is as follows: Verification condition setup and simulation solution: Set up dynamic collision verification conditions corresponding to the failure analysis, apply initial velocity, load and boundary conditions that are completely consistent with the comparison benchmark, and perform dynamic simulation.

[0057] Multi-dimensional accuracy verification: The simulation results of the model are compared with the benchmark in a multi-dimensional and quantitative manner, with a focus on verifying the following aspects: Energy absorption sequence verification: Compare the energy-time history curves of the model and the benchmark for the whole and key energy-absorbing components (such as crush tubes and buffers) to verify the consistency of the total energy absorption and the proportion and timing of energy absorption of each part.

[0058] Failure Mode Validation: Compare the formation sequence, spatial location, and deformation mode of plastic hinges in the model and reference data. Check whether the predicted plastic hinges appear in the expected sequence and location, and whether their deformation morphology (such as bending direction and crushing mode) is consistent with the actual situation.

[0059] Dynamic response verification: Compare the time history curves of key physical quantities, such as the displacement-time curve of the coupler connection point, the acceleration-time curve of key measuring points, and the dynamic impact force-time curve.

[0060] Model Iteration and Correction: Define clear model convergence criteria (e.g., critical force and displacement response errors less than 10%, and correct failure mode predictions). If all criteria are met, the model is considered validated. If any critical index is out of tolerance or the failure mode prediction is incorrect, the plastic hinge parameters are rechecked, and iterative corrections are performed until the model passes validation.

[0061] Computational efficiency evaluation: Under the same hardware platform and similar simulation duration, the solution time of the model built by this technical solution was recorded. This solution time was compared with the solution time of a traditional nonlinear finite element model with equivalent modeling accuracy to quantitatively evaluate the improvement in computational efficiency.

[0062] The model constructed in this embodiment has a computational scale far smaller than that of a nonlinear finite element model of equivalent precision. The finite element method requires dividing a large number of meshes and calculating the stress and strain of each element, while this embodiment describes the system using discrete rigid bodies and concentrated plastic hinges, significantly reducing the order of magnitude of the degrees of freedom in the dynamic equations. This method achieves an order-of-magnitude acceleration in computation, making it possible to conduct extensive parameter studies, load case selection, and optimization design within the engineering development cycle.

[0063] Traditional multibody dynamics models treat structures as rigid or ideal elastic bodies, failing to predict bending and fracture during collisions. This embodiment systematically identifies and quantifies key failure modes and plastic hinge parameters, assigning precise mechanical properties to kinematic pairs, including plastic deformation stages and failure criteria. This enables the model to dynamically predict the sequential triggering of plastic hinges, progressive structural crushing, and eventual component fracture due to excessive rotation, significantly enhancing the depth of collision safety assessment.

[0064] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for modeling the dynamics of a plastic hinge in a train coupler and buffer device, characterized in that, include: Establish a structural discretization criterion, based on the geometric configuration and expected deformation region of the train coupler device, to determine the criteria for discretizing a continuous structure into several rigid body components and plastic hinge connection points; The failure modes of the hook-and-buffer device under different collision conditions are identified, and key mechanical parameters for defining the plastic hinge are extracted to generate a master list of plastic hinges. At the same time, benchmark simulation data for model verification are obtained. Based on the discretization criterion and the plastic hinge master list, the hook and buffer device is discretized into a multi-body system topology structure consisting of several rigid bodies connected by kinematic pairs. Based on the multibody system topology, inertial parameters are defined for each rigid body, including mass, center of mass position and moment of inertia. The corresponding kinematic pairs in the multibody system topology are given mechanical properties including nonlinear constitutive relations and failure criteria. Plastic deformation and fracture behavior are simulated to establish the multibody dynamics model of the hook and buffer device. Based on the multibody dynamics model, the system dynamics equations are assembled and solved to obtain the dynamic response of the hook buffer device during the collision process and determine the simulation results. The accuracy of the multibody dynamics model is verified and the computational efficiency is evaluated by comparing the simulation results with the benchmark simulation data.

2. The method for modeling the plastic hinge dynamics of a train coupler and buffer device according to claim 1, characterized in that, The structural discretization criteria include: Criterion 1: Divide the structure at locations where there is a specified relative motion in the structural design; Criterion 2: Delineate at potential areas of plastic hinge, yield, or fracture; Criterion 3: Under the premise of satisfying Criterion 1 and Criterion 2, large-sized components with no risk of failure should be simplified as a whole.

3. The method for modeling the plastic hinge dynamics of a train coupler and buffer device according to claim 1, characterized in that, Identify the failure modes of the hook-and-buffer device under different collision conditions, extract key mechanical parameters for defining the plastic hinge, and generate a master list of plastic hinges, including: The dynamic response of the hook and buffer device under different collision conditions was analyzed by finite element simulation to identify local plastic deformation regions. The identified local plastic deformation regions are abstracted as plastic hinges. The type, spatial location, and critical load of the plastic hinges are extracted. A master list of plastic hinges is generated through equivalent merging and contribution filtering.

4. The method for modeling the plastic hinge dynamics of a train coupler and buffer device according to claim 3, characterized in that, The main list of plastic hinges is generated through equivalent merging and contribution filtering, including: Establish an initial list of plastic hinges, compiling all plastic hinges identified under all collision conditions, along with their corresponding types, spatial locations, and critical load parameters; The plastic hinges in the initial list of plastic hinges are judged for spatial proximity and mechanical mode consistency. Several plastic hinges with spatial distance within the preset range of structural feature size and the same or similar mechanical mode are merged into an equivalent plastic hinge. The critical load is taken as the minimum value among the merged plastic hinges. Based on the principles of energy absorption contribution rate and deformation dominance, minor plastic hinges with negligible impact on the overall mechanical response are eliminated. The elimination criteria are: the average energy absorption contribution rate of the plastic hinge is lower than the preset range, and the failure does not dominate the overall deformation mode. The plastic hinges that are ultimately retained are globally sequentially numbered to form a master list of plastic hinges containing each type of plastic hinge, three-dimensional coordinates, and critical load.

5. The method for modeling the plastic hinge dynamics of a train coupler and buffer device according to claim 1, characterized in that, The types of kinematic pairs include ball joints, universal joints, cylindrical joints, and translational joints.

6. The method for modeling the plastic hinge dynamics of a train coupler and buffer device according to claim 1, characterized in that, The mechanical properties include: The characteristics of free rotation at extreme angles and limiting impact of rotating structures; The nonlinear force-displacement constitutive relationship of the axial crushing energy absorption component; The moment-rotation constitutive relationship and failure criterion for bending plastic hinges.

7. The method for modeling the plastic hinge dynamics of a train coupler and buffer device according to claim 1, characterized in that, Based on the aforementioned multibody dynamics model, the system dynamic equations are assembled and solved, including: Based on the rigid body partitioning, inertial parameters, kinematic pair topology, and plastic hinge mechanical properties, corresponding rigid bodies, kinematic pairs, and force elements are created and integrated into a complete multibody dynamics model. Set up state monitoring and switching logic for each plastic hinge. When the plastic deformation of the hinge reaches the preset failure criterion, automatically trigger the locking of the degree of freedom of the corresponding kinematic pair or remove it from the system connection relationship. Perform static equilibrium analysis on the integrated system, calculate and verify the total degrees of freedom of the system; By applying collision loads and boundary conditions, the dynamic equations of the system are solved by numerical integration to obtain the dynamic response of the hook and buffer device during the collision process.

8. The method for modeling the plastic hinge dynamics of a train coupler and buffer device according to claim 1, characterized in that, Verifying the accuracy of the multibody dynamics model includes at least one of energy absorption sequence verification, failure mode verification, and dynamic response verification.

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