Research On Modelind, Simulation And Virtual Test Of Riding Comfort Of Passenger Railway Vehicle

The railway passenger transportation of our country is meeting with a historic opportunity of great-leap-forward development, which is accompanied by the inevitable requirements of high quality riding comfort of passengers. To study the riding comfort of railway passenger vehicles with advanced theoretical analysis model and computer simulation technology is the basic contents and crucial sections to ensure the running quality of vehicles. Static comfort and vibration comfort of vehicles are two important factors influencing the riding comfort of passengers. However, in previous research of static comfort there lack quantitative analysis method and evaluation model for analyzing the sitting comfort with consideration of various characteristic of human body. In present research of vibration comfort, there is no theoretical analysis model with comprehensive consideration of passenger masses, the flexibility and spatial characteristics of carbody. Further study of the vibration effect of passenger masses on lightweight high-speed passenger vehicle and the applicability of applying present riding comfort evaluation standard on the sleeping cars are still not carried out. Additionally, in the aspect of simulation technology, the virtual test integrated with technologies of virtual prototype and virtual reality is not applied in the analysis and simulation of vibration comfort of railway passenger vehicles. To solve the above problems, systematical studies are carried out in this paper. The detailed contents are as follows:(1) Using geometric and feature modeling technology, the CAD models with various human body percentiles through parametric modeling is established. A circular interference check method is used to implement adaptive match between CAD models of human body and seat to realize analysis and evaluation of human body with various characteristics. As a result, the objective basis for virtual test of geometric comfort of sitting human body is provided. On this basis, a three-level fuzzy assessment model for evaluating the riding comfort of train seat is established. The three-level structure factor sets in the model are composed of genders, human body percentiles and joint angles, and the assessment sets are composed of series of train seats with various design schemes. While the assessment model can quantitatively compare the geometric comfort of different train seats.(2) The biomechanical vibration properties of seated human body and the flexibility characteristic of carbody are analyzed, and a vertical coupled dynamic vehicle model including sitting human-bodies and flexible carbody is built with comprehensive consideration of the influence of passenger masses, structure characteristic of carriages and flexibility of carbody. On this basis, the motion equations of the coupled dynamic model with freedoms of vehicle and sitting human body are derived. Through converting multi-excitation to single-excitation of wheelset, the random vibration simulation excited by track irregularity is realized. This model is used to carry out a quantitatively comparative analysis of the random vibration responses of the vehicle in conditions of full-load and no-load. The results show that the passenger's effects as coupling vibration factors are obvious, thus ignoring of the influence of crew's masses may result in bigger miscalculation.(3) The vibrating isolation effect of sleeping berth and the vertical vibration response characteristic of supine human body are analyzed. A spatial dynamic system including supine human body, sleeping berth and vehicle is built with considering of the special compartment structure of sleeping car. Applying the vibration comfort assessment standard for supine human body, the simulation flow of vibration comfort of human body in sleeping car is built. With this model, it analyzed the difference between Sperling index and GB/T18368-2001 index for evaluating the vibration comfort of a railway sleeping car, the influence of sleeping berth parameters and the difference of vibration comfort of various berths.(4) The virtual test method for vibration comfort of railway passenger vehicles is carried out in a deep sense. To build a virtual proving ground is the basis and precondition of virtual test. The frameworks of virtual test of vibration comfort of railway passenger vehicles are established with self-built theoretical model and multi-body dynamics software as the computation engine for virtual test, and virtual instrument as tool for visualization of virtual test data. In the transmission mechanism of virtual test data, the spatial track mathematical model defined in virtual proving ground is applied as a tie to uniformly determine the conditions of rail lines within both virtual prototype environment and virtual reality environment, which guarantees an effective connection and integration between dynamic simulation and vision simulation.(5) In the study of construction of virtual proving ground for vibration comfort test, three-dimensional virtual reality model of train is built through three-dimensional CAD modeling, optimization of virtual reality model, texture mapping and DOF technology. The virtual proving ground based on real terrain DEM data is built, and the spatial mathematic model of track based on piecewise functions is established, and the mapping mechanisms for local coordinates of every sectionalized line converted to landform spatial coordinates is realized. The stylized generating method and realization technology of geometric data of track in landform are discussed.(6) The research of multi-body dynamics simulation of vibration comfort of railway passenger vehicles based on virtual prototype technology is carried out. Analytical resolution program is developed to automatically transfer the inflexion data of tracks extracted from virtual proving ground to prototype environment. The multi-body dynamics simulation for vibration comfort of railway passenger vehicles is realized based on Adams/Rail, and it provides powerful support of vehicle kinematics properties for virtual test of vibration comfort.(7) In the research of dynamic visual simulation of railway passenger vehicle, the image frame sequences generated from the vehicle kinematics data for driving the scene model of train can accurately simulate the train running in the established orbits on virtual proving ground. Using development tools of Measurement Studio, the virtual instruments are established to present vehicle speed, acceleration of vibration and vibration comfort index in real time.