Oriented Multi-Body System Virtual Prototyping Technology for Railway Vehicle

1.1 Railway vehicle virtual prototyping In recent years, knowledge-based new product competition has become the mainstream of manufacturing competitiveness. As an important way to simulate various problems of complex mechanical systems, virtual prototyping technology is being widely used. It supports concurrent engineering and emphasizes the overall product performance, and strives to simulate the product function and behavior. Based on considering the overall product performance in three-dimensional CAD and its following function modules, virtual prototyping does the innovative design and informs a digital prototyping which do not depends on the physical prototype. Virtual Prototyping (VP) is a new product design method generated in the recent 20 years. Based on computer simulation, VP embodies not only the product's innovative design but also the product's risk-free digital test, especially suiting for high cost trial production of complex mechanical system development. The main elements of VP are: virtual prototype model virtual test analysis virtual prototype evaluation (qualitative and quantitative). VP embodies the global optimization process which is based on computer simulation and aims to get more realistic products. It supports “Top-to-Down” design approach. The main techniques of VP ---CAX, multi-body system modeling and analysis, simulation, optimization, visualization and VR technology are used to get a digital prototype with optimized performance, thereby the development costs and the reliance on physical prototypes are reduced, product qualities are improved, and time-to-market is accelerated. Railway vehicle system which belongs to complex mechanical system areas is composed of mechanical, electrical, active control and drive systems (power distributed EMU), and its main part is mechanical systems. The quality of vehicle performances is the key problem of the vehicle product development. Based on the railway vehicle product design, especially the design results of the whole product machine, the performances include: dynamic performance, operational safety, aerodynamics, air-condition, strength and fatigue reliability. Therefore, it is inevitable to research and develop the railway vehicle virtual prototyping for advanced manufacturing technology. It is also inevitable to research the railway vehicle virtual prototyping technique for the railway transportation equipment, especially for the high-speed, heavy haul train. The past railway vehicle product development mainly takes the following forms:

2. Integrate multi-domain prototype model.Based on three-dimensional CAD model, consider basic data of various characteristics of railway vehicle, such as physical information, assembly information, etc. 3. Take into account the integrality of the prototype model.Integrate seamlessly the multibody dynamics environment and integrated model based on CAD, make dynamic automatic modeling and solving according to the CAD model, and build railway vehicle multi-body system with nonlinear dynamics simulation and computation.4. Take into account the integrality of the prototype mode.Integrate seamlessly the integrated model and CAE analysis environment; analyze and simulate the structures, fatigue and the reliability performance for railway vehicle; simulate and calculate the model of airflow field and temperature field outside and inside the train.5. Combine the virtual reality technology and build a virtual prototype test platform.
Considering the simulation of human factor and hardware in the loop, the assessment analysis of railway vehicle virtual prototype should be built 6. Build the design platform of key components for railway vehicle, comprehensively evaluate the manufacturability to achieve the aim of railway vehicle virtual prototype based on CAX / DFX and optimize the design of railway vehicle virtual prototype.7.In accordance with PDM principle, establish the data management platform of the entire system to build the system simulation management platform, and make the system an organic whole.According to the specific case of railway vehicle virtual prototype, the program of establishing the "railway vehicle virtual prototype research and development platform" is shown in Fig. 2-1.The core part of the whole project should be achieved in high-speed local area network platform which supports concurrent engineering methodology and is composed of highperformance PC.The platform should be the overall situation to solve problems related to the global system.Considering the relationship of various parts of the virtual prototype, it can regulate and coordinate the running of various sub-systems, and share the information and resources to achieve the overall goal of railway vehicle virtual prototype.Different constrained work is carried out concurrently on the basis of the management platform.There are mainly five major modules according to the product development process: PDM module, product research module, product performance analysis module, product virtual manufacture modules and product running simulation module, as shown in Fig. 2-1.

Fig. 2-1. Digitization process of the product research and manufacturing
In accordance with the above ideas, the concept of the platform for railway vehicle virtual prototype is shown in Fig. 2-2.Structure of this part is divided into four main sections: 1. Product digital design and simulation basis system This part is composed of distributed network running software and hardware, virtual prototype concurrent design and simulation systems, distributed database servers, clusters computer group and etc. 2. Product innovation design system based on three-dimensional CAD Around the mainstream 3D CAD software, a railway vehicle product innovation design platform which includes four major parts is built: a. Model design of product digitization This model is the basis for subsequent design and analysis.This section includes: product scheme design, design automation, serialization and modularization and optimization design, different model library for railway vehicles; b.Product modeling based on physical properties Interface the following performance and simulation, establish the interconnected middleware of CAD and CAE platform to achieve the model unity; c.Design oriented manufacturing This section is mainly designed for cost, assembly, processing techniques and other manufacturing characteristics.Evaluate the economy, manufacturability, assembly ability of products according to a comprehensive perspective to reduce the risk of trial and trial times for the final product optimization services.This section mainly includes: virtual assembly and virtual manufacturing; d.Product data management (PDM) This part mainly completes the integration management of the design and analysis of manufacturing data from database server.

Digital prototyping-oriented performance analysis
Based on the above product digital description, mainly simulate the function, behavior and running environment of the products: railway vehicle multi-body dynamics analysis, multi-field coupling dynamic analysis and simulation, strength and fatigue reliability analysis of key parts, analysis and simulation of railway vehicle structural vibration noise, simulation of mode, brake and shock response, analysis and simulation of aerodynamics and air noise, co-simulation of multi-field coupling and etc.

Railway vehicle running simulation
Combining with the digital model and various performance analysis results, the mixed digital simulation of the railway vehicle dynamic, which is a multi-domain environment coupled simulation, includes: railway vehicle running simulation and etc based on virtual reality technical.Those four parts above form a more complete railway vehicle virtual prototype development platform.On this platform, PDM, concurrent simulation tools and platform are the linkage to achieve these functions.Fig. 2-3 is the data flow analysis for railway vehicle virtual prototyping engineering.The part with thin red line means that exchange data is needed before data processing.From this it can be seen that the three-dimensional model is the entire data center of the system.The key processes of this part are: establish a reasonable railway vehicle database model and the database structure of the whole vehicle model, open the system to all data format; establish the database coordinating relationship between various databases; deal with concurrency control and collaboration issues between various database.Fig. 2-2.Innovation system of railway vehicle virtual prototype www.intechopen.comFig. 2-3.Data flow analysis for railway vehicle virtual prototyping engineering 2.2 Innovative design platform for railway vehicle virtual prototyping F r o m F i g . 2 -4 , i t c a n b e s e e n t h a t e s t a blishing a reasonable, reliable and adequate information model is the core of the entire system data processing.The model database is a complete virtual prototype model.The work will be done by the product design platform.This section can rely on the function of three-dimensional solid modeling such as CAXA to improve itself, the specific functional requirements are: 1. Have all functions of generating three-dimensional solid model; 2. Generate the physical model and simplified model (simplified according to the requirements of the mechanical model) corresponding with three-dimensional solid model; plan the model according to the actual performance including materials, quality, mass center, surface area, volume, inertia moment, mechanical properties curve function, stiffness, composite calculation of main/sub-section and etc; classify the entities with performance characteristics in accordance with the similar principle.3. Have the part assembly function, it is design for assembly (DFA) ,and can be combined in accordance with the model tree to generate a separate entity model, so that it has its own physical property performance, for example: the change of the mass center, surface area, volume, inertia moment, materials composition and etc. 4. Establish constraint models of all kinds of components in accordance with the constraints.It should have the function of kinematics analysis which be able to detect interference, moreover can simulate the deformed elastic components. 5. Have parametric function which has both features and structural parametric characteristic to generate the parts automatically, and can modify the entity parameter manually or automatically according to the optimized result.6. Geometric model must support the STEP standard and support design for manufacturing (DFM) to expand the virtual manufacturing; 7. Have the management function for all model databases and the whole vehicle database.
Each component has a physical (including the simplified model) and geometric model sub-database.All model databases should be opened to all, and sho uld have the function of automatic indexing.8.All geometric and physical models must support the conversion with kinds of software interface and a strong re-development based on VC interface; The architecture and data flow of this platform is shown in Fig. 2-4.

Performance analysis platform for railway vehicle virtual prototyping
Railway vehicle performance analysis is mainly composed by dynamics, intensity and fluid analysis, with the core dynamics based on meshing analysis.They are established on the basis of three-dimensional CAD digital model.The main ways to analyze railway vehicle are shown in Fig. 2-5.

Fig. 2-5. Main ways to analyze railway vehicle
This platform integrates the railway vehicle parametric design and vehicle dynamics computation.Based on the railway vehicle dynamics simulation software, using multi-body system dynamics computation method and model database from entity CAD design, settle the model first, which includes error checking, feature and parameter identification and extraction to form the dynamic computation model.According to the simulation run line conditions, do simulation solution and analyze the three elements(safety, stability, comfortability) of the railway vehicle to obtain the critical instability speed, ride comfort, dynamic wheel-rail forces and other targets.The dynamic load and dynamic stress from simulation can be used for strength and fatigue reliability analysis.Send the result database is transferred to optimization design module to do parameters and structure optimization.The dynamic computational platform for railway vehicle is shown in Fig. 2-6.

Strenth analysis Lift prediction
The key of this part is the extraction of the whole vehicle model database including entities simplification, combination, extraction of the physical properties, and extraction of coordinate location of the component and etc, with the requirement of using all data from the model database; In addition, data visualization and classification of the results also need interface development.This is the main context of this chapter.

Running simulation of the railway vehicle
The platform does the final integrated simulation of comprehensive test and evaluation to virtual prototype.Related tools are used to produce various effects, and the main task is to simulate various operating conditions of the vehicle to make clear people's understanding and awareness of the vehicle in the simulation loop.In other words, it means to regard people as an intelligent individual to do all performance testing of the virtual prototype, including: safety, comfortability, stability and so on.The core of this platform is virtual environment which has the following contents: vehicle LOD models, various result data form performance simulation computation, vehicle kinematics model, virtual reality interface device, a variety of effects tools (all kinds of dynamic simulation tools, brake tools, control simulation tools, etc.), virtual scene (bridges, tunnels, rail, the distance light scenes, etc.), control mathematical model, traction model, braking model and etc.The key of this part is how to integrate these multi-dimensional information as a whole and simulate various properties of the railway vehicle virtual prototype, saving the dynamic test database as a certain prototype database ultimately.Running simulation of the railway vehicle is shown in Fig. 2-9.

Design model of the railway vehicle digital prototype-take bogie for an example
In the virtual prototyping, the first is to get the virtual prototype model which must rely on three-dimensional CAD software.How to get the virtual prototype model fast and accurately is the basic part for speeding up product design.According to the parts that can be parameterized, prototype model automated design ideas and methods are proposed.Take the bogie design for an example, this approach is detail studied.The following process of this method is shown in Fig. 2-9.Around the bogie design automation, its implementation framework is shown in Figure 3-1.In object-oriented development environment, the automatic design of the bogie parts with user-friendly interface is completed, the data management library is established, and the changes and assembly of the bogie vehicle model (mainly for the wheelset and spring components) are implemented.At the same time, the extraction of bogie performance attribute parameters is completed, generated bogie model is saved as sel-definied file automatically, and the bogie component model and corresponding data are reproduced in the file browser.Thus, the data for dynamics calculation platform and finite element analysis platform are subsequently provided.Fig. 3-1.Structure graph of the system framework Since there are many parts in the bogey, the secondary stiff spring is taken here for an example.First, the basic design flow is obtained according to the design requirement.According to the design results, based on the technical support of COM component interface, API, CAD environment and database under three-dimensional CAD redevelopment environment, drive 3D rendering engine and draw out different specification three-dimensional model of the secondary stiffness spring to get the virtual model.The design results are shown in Fig. 3-2.With the same process, other parts of the bogie can also be designed.3-D figure of the wheelset and wheel axle which was obtained from automatic design is shown in Fig. 3-3 and 3-4.
The automatic assembly process of the bogie is shown in Fig. 3-5 (some small parts omitted).Through this automatic process, it only takes less than one minute to complete bogie assembly in SolidWorks.With the parameters of the previous parts, a different type of bogie can be designed easily which speeds up the design rate and efficiency.

Performance extraction of railway vehicle digital prototype oriented multibody system 4.1 Method
Existed CAD software has been able to get a very complete product configuration and can get the relationship between the product and components in its design space, but it is mainly designed for manufacturing.Therefore, functionality and output data provided by CAD rarely faces to the subsequent performance analysis which has been confirmed in the analysis of many product cases.In the subsequent product performance analysis which includes multi-body dynamic analysis, strength and reliability analysis and other performance analysis, CAD still only provides a preliminary physical model which can not get its own performance properties from the entity itself.So the attribute data of product components need to be obtained by physical experiment.The difficulties of data collection, the investment of testing equipment and the cost of product development are enlarged.Moreover, with the perspective of practical effect, in the following process of passing the performance analysis function, due to precision, algorithm, solving model and other reasons, CAD models will lose some information that may lead to too much human intervention and waste a lot of human and material resources.Even a small mistake can result in the fact that the prototype analysis can not keep going normally.So, a lot of virtual prototype analysis at present still do their own studies.CAD is only responsible for the design.The model is re-modeled after being simplified according to the product function in dynamic analysis.The model is carried out according to the initial design scheme in finite element analysis.So these lead to serious gap between analysis software and CAD, also lead to no unification of the analytical results from different analysis software.Enterprise even does not know which algorithm is correct, so they still choose the conservative design approach such as raising the safety factor and so on.This makes people misunderstand the virtual prototyping technology.
The real reason for this misunderstanding is only considering the geometric modeling in the CAD, but not considering modeling of product components and the full machine.By putting the extraction of the product model's performance data in performance analysis module artificially, the integrity of the CAD model itself is ignored.In fact, the product CAD model provides geometric model and physical properties of the products and components simultaneously, so the physical properties should be modeled in CAD and property definition should be considered in CAD design to provide a complete integrated model for the following performance analysis which will unify the model.These two ideas are summarized in Fig. 4- The proposed method provides an abstraction layer between CAD and prototype performance analysis in order to obtain a satisfactory virtual prototype model.

The requirements of virtual prototype model for product performance analysis under multi-body system
The ultimate virtual prototype not only depends on the completeness of the design, but also depends on the correctness of prototype analysis, which will replace the product physical prototypes to achieve product performance analysis, testing and evaluation.For mechanical system virtual prototyping, the main performance analysis tools are: strength analysis, life prediction, multi-body dynamics, fluid analysis (gas, fluid dynamics) and so on.
The basic data of the analysis are from the three-dimensional CAD design itself.Take multibody systems analysis for example, the following performance data should be provided by the system: For rigid body: identification number, quality, geometry shape, mass center, moment of inertia, location coordinates, position coordinates, degree of freedom, material density, etc.For kinematic pair: identity, type, location of hinge points and associated two rigid, position coordinates of the hinge point, location coordinates of the hinge point, the number of degrees of freedom.In general, kinematic set are: rotating set, sliding set, planar joint, cylindric pair, cardan joint, spherical pair, gear pair, etc.
For the elastic body: identification number, quality, geometry shape, mass center, moment of inertia, location coordinates, freedom, material density, modulus of elasticity, mode, damping, etc.For element force: serial number, coordinate position which connects two rigid bodies (location of the up and down points), physical definition of the force element type (stiffness, damping, friction and other characteristics).
The data are given by their own characteristics of the product components such as quality, geometry shape, mass, inertia, density, modulus of elasticity, stiffness, damping, etc.Some are obtained from product assembly relationship and space movement characteristics such as: position, location, connection relationship of hinge and multi-body, position coordinates.Many of these properties can be extracted from the CAD model, but all current CAD systems do not provide this function.So the building of an abstraction layer between CAD and prototype performance analysis is proposed to obtain a satisfactory virtual prototype model as shown in Fig. 3-6.
In theory, the second defined data is directly from the CAD design model.It should be more accurate and more reasonable, but the difficulty of CAD may increase.If taken as a separate function layer designed by design and analysis staff, this difficulty can be simplified.In the first approach, manufacturing are mainly considered after the CAD model is designed, without considering the definition of products and component attributes.Most are obtained by analyzing the functions supplied by analysis tests tools to do re-modeling.

Virtual prototype performance design solutions based on CAD
From Fig. 4-1 (b), in order to achieve the aim of extraction from CAD directly or attributes definition, higher requirements are needed on CAD functions.However, the current CAD can not meet this requirement obviously, so its function should be extended.For a variety of CAD software, they have re-development functions, such as ToolKit of Pro-E, SDK API (Application Programming Interface) of SolidWork, SDK (Software Development Kit) of CAXA.This study is based on three-dimensional CAD of CAXA.
Prototyping can be obtained from three-dimensional solid model design, Extend Data Object (EDO), internal and extended Catalogs (a pixel classification function of CAXA software) and the second development.The model attribute definitions can be defined through an external interface or SDK development of CAXA platform to obtain an extended IGES file.The so-called extensible IGES files are to keep the original model data interface and format unchanged, increase the special format data in the end of the file system which is mainly used to define the properties of the model data.This file can interface the common application software and can be used for the system which has both specialization and generality.Therefore, the obtained data are data blocks based on IGES that can describe model properties.Those data blocks form the whole data model are for the platform.
Obviously, the prototype model is actually a combination of a space abstracted physical prototype and the entity model.Entity model is obtained from the CAD design and attached to the physically abstracted model.The abstracted model not only defines the properties of the product components, but also maps to the graph-like model structure according to their functions and relationships, reducing the functionality according to the follow-up requirement.In order to overcome the model data consistency, several key issues must be solved, and they are: define and extract the data directly in the solid model, mesh finite element in the solid model automatically in accordance with the requirements of FEA, extract model directly to do visualization of functional analysis subsequently and so on.The relationship of the model and performance analysis based on CAXA is shown in Fig. 4-2.
Fig. 4-2.Relationship of the model and performance analysis based on CAXA Property definition for the performance analysis can be achieved by several redevelopments such as EDO, API, Catalog and so on.

Extraction of the virtual prototype performance attribute based on CAXA
Railway vehicle system is a typical complex mechanical system. in the view of multi-body dynamics, this system is a complex system which interacts with a multi-body system.It can be simplified as: rigid body (soft body), hinge, force element, force, and etc.It can be defined as following: 1. Relative to the suspension system, the stiffness of the car, bogie, wheelset and other qualities is much great, so they can be defined as rigid body without considering their flexibility.2. Define the suspension as force element; 3. Define the force and force couple of the rigid body as the external force.For the body in the mechanical systems virtual prototyping, the most important is to describe its geometric and physical relationship in space.The architecture process of the performance and attributes obtained system for the entire multi-body system is shown in Fig. 4-6.Fig. 4-6.Property extraction of the multi-body system based on CAXA In the extracted process, coordinate transformation of design space, assembly space and feature space of the part is used in CAXA.Various properties of abstract defined bodies based on the geometric topological core are obtained.For unabstracted properties, the rich re-development interface function is used for extension, more suitable methods are: EDO, Catalog, AttributeSet, embedded database and etc.
Once the model is defined and extracted, the virtual prototype based on CAD with unified regulations and property definition can be obtained, and pass to the performance analysis module.Physical abstracted model corresponds with entity model through the marker and serial number.It strictly reflects the space topology construct relationship between various bodies.Their mapping forms an integrated digital model which has CAD features and physical features of product components to the following performance analysis.Property extraction in CAXA is shown in Fig. 4-8.

Transition of design prototype model to multi-body system analysis model based on virtual prototype--the establishment of topology structure
Mapa topology structure of multi-body system in CAD environment through property modeling, and store it in a neutral file format.This format retains the defined topology of the multi-body system including assembly location relationship, position and orientation relationship of the space coordinate, constraint relations and constraint definitions between bodies and etc.Output a corresponding geometric model simultaneously which strictly corresponds to the part or assembly in the neutral file.The initial data for multi-body system modeling abstracted from the CAD modeling are obtained.The transition from virtual prototype model to the multi-body analysis model is achieved.
Decode the neutral file first.Obtain the rigid body, marker body, constraint, element force, applied force and etc according to established formats.Resume the space topology of the multi-body system according to the defined property.For example, rigid body a, b, c, has marker i, j, k, and force d, e, f, respectively, and the associated relationships ii, jj, kk, ee have been defined.The space topology structure can be resumed which is shown in Fig. 5-1.Fig. 5-1.Rebuild multi-body system structure Although the physical models based on multi-body system are obtained, it has not been attached to the geometric solid model.In order to obtain a visual model, it needs to output the neutral file model in CAXA.In accordance with the decoded format, it can be IGES, STL, OBJ, 3DS, etc.In this study, 3DS model is adopted.The way to obtain the geometric model of the prototype is shown in Fig. 5-2.

Fig. 5-2. Transition of virtual prototype of analysis model
From the figure above, multi-body description of the physical model corresponds to the objects given by geometric entities exactly.These objects determine to give which solid through classifying the point, line and surface.According to the assembly sequence of virtual prototype in CAD and marker body of the neutral file, their position relation is mapped.Properties such as transformation relation between the fixed coordinate system and the inertial coordinate system, transformation relation between the marker coordinate system and the fixed coordinate system, Euler angle corresponded to the rigid body, position and orientation of the marker coordinate system, the relationship of the defined constraints (restriction of the degree freedom), position and orientation corresponded to the force, have been strictly defined in the neutral file.Finally it is located by mapping the coordinate system of virtual prototype and space coordinate system of the visualization module to obtain the satisfactory model of multi-body system.
In accordance with the virtual prototype form CAD, describe them as objects with multibody meaning using object-oriented idea, map them into 5 linear chains, and form a space topology model of visualized multi-body system.This model is also built on the principle of framework based on OpenGL and object oriented graphics.The existed relationship of this model in three-dimensional visualized space is shown in Fig. 5-3.

Topology construction of the railway vehicle multi-body system
The above visual model suits for not only mechanical multi-body system, but also railway vehicle.Considering the particularity of the railway vehicle multi-body system solution, according to the given multi-body system analysis software, the special object is established as shown in Fig. 5-4.The visualized model can be defined in the system or imported form the CAD model directly.These objects include: Car, Bogie, Wheelset, Track, Damper, Rod, Spring and Friction plate, which complete vehicle component modeling, simulate for vehicle model running, and prepare for the dynamic calculation.Create the solid model according to the associated sign of the given two ends.If the relative marker position changes, the shape and position or orientation of the model can be adjusted.It has basic functions of three-dimensional simulation.Four categories have their own "dynamic" property pages.Every category has its corresponding variable receiving and data transformation which prepare initial data for dynamics solver.
Components of four categories are stress-carrying parts and are built by inheriting the CForceElement in the virtual prototype system.In order to facilitate the unified management of data, four categories created by this module are added to the CForceElementList chain, and also to the ObjectList chain for the visualization need.

Multi-body system analysis
The model established includes variety data for analysis of multi-body systems.After transiting to analysis model, multi-body analysis will be done by analysis module.Since the universality of the model and plug-in nature of the multi-body analysis module, many solvers can be used to compute for common mechanical multi-body system, such as Adams, Simpack, etc.For railway vehicle multi-body system, because of the field specialization, a specialized analysis module is needed to do analysis, such as Adams / Rail, railway vehicle part of Simpack.A software system is self-developed such as TPLdyna, VSDS.TPLdyna is developed by State Key Laboratory of Power Traction of Southwest Jiaotong Universtiy.VSDS is developed by Dr. Jue Wang of SWJTU.They both have multi-body system features but have different solvers.This study supplies the model interface to them.Here especially supports Dr. Jue Wang'VSDS, see Fig. 6.10-14.

A case study of railway vehicle virtual prototype oriented to the multi-body system
6.1 Analysis idea According to the modeling method above, space topology structure of the railway vehicle is shown in Fig. 6-1.B1 is car, B2 and B3 are frameworks, B4-B7 are wheelsets, B8 is track, FE1-FE6 are force elements, F1-F4 are wheel-track contact forces.Defining the force element, hinge and external force as directional has two aims: First, defining one of two adjacent objects as a reference object is to describe the relative movement of another.Second, it aims to define the positive direction of applied force and reacted force between the adjacent objects.

Fig. 6-1. Topology description of the railway vehicle multi-body system
To accomplish the railway vehicle virtual prototype analysis, take multi-body system analysis as an example, the processing description is shown in Fig. 6-2.

Fig. 6-2. Analysis flow of the railway vehicle virtual prototype
The process is actually obtained directly from the virtual prototype → properties extraction of the multi-body system model →transition of geometrical and physical model of multibody systems → multi-body systems visualization modeling and mathematical modeling building → kinematics and dynamics solving of the multi-body system.This process is like mechanical system product development process, reflecting the integrated process from design model to analysis model, then to solve model, and reflecting the cycle iteration in product design process.This process supplies a theoretical and practical basis for study of product optimization process and intelligent design process.

A case process study of railway vehicle virtual prototype
Since the system is more complex, in order to obtain more significant technical route, the railway vehicle design model is simplified.The railway vehicle virtual prototype process is achieved.

Fig. 2
Fig. 2-4.3-D design platform for railway vehicle oriented virtual prototyping

Fig
Fig. 3-5.Automatic assembly process of the bogie Fig. 4-1.Two different methods to definite the property

Fig. 5
Fig. 5-3.Existed relationship of this model in three-dimensional visualized space

Fig. 5
Fig. 5-5.Associated structure of the railway vehicleA railway vehicle multi-body system model can be generated rapidly according to the above description.The defined model is shown in Fig.5-6, which is a simplified model.Fig.5-7shows that import models from the design.

Fig. 6
Fig. 6-8.Model resuming and checking in analysis view 9. Check the of the data imported, perfect some incomplete information.Test results show that the model is resumed completely and property data is right.The data meets the dynamics and simulation requirements.Then transition of model to performance analysis module is shown in Fig.6-9.

Fig. 6 - 9 .
Fig. 6-9.Transition of model to performance analysis module 10.Load the track, set the measure variables and simulation parameters, and prepare for the dynamics calculation and simulation.Post-processing of the analysis module is shown in Fig.6-10.