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The Development of Software for the Wheel Rolling on the Soft Ground

Author: SongHongJian
Tutor: FuHong
School: Jilin University
Course: Computer Software and Theory
Keywords: Vehicle terramechanics Discrete Element Computer Simulation Computer modeling Contact model Mechanics calculations Needs analysis
CLC: TP391.72
Type: Master's thesis
Year: 2011
Downloads: 105
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Abstract

The vehicle ground mechanics, a subject of the study the interaction between the vehicle and the ground has a broad development space and great value, many domestic and foreign scholars have done a lot of research in this area and achieved rich results . Based on the research topic to the vehicle terramechanics as combination of discrete element method, and computer simulation technology, developed at the same time this can be used to simulate a two-dimensional force rolling wheels on loose surfaces software, which is the vehicle ground mechanics expand The research project also has certain characteristics. Vehicle ground mechanics development so far, has formed a physics experiments, theoretical research and simulation studies based on computer technology, the two research methods have their own scope of application. Consolidated the status quo at home and abroad, on the vehicle terramechanics research, summed up in three characteristics: wheel rigidity simplified analysis of the movement of the vehicle, from a global point of view, through physical experiments. The subject thought the use of discrete element method for the wheels - ground interaction system modeling, wheel emulation types can choose between \process, research wheels rolling on the soft ground. The core idea of ??the discrete element method, macro research object in space and two layers of surface refinement, as a study by a large number of bulk unit (\refined by the \Target for the completion of the research topics of this paper are mainly the following aspects. Design data source data source for storing CAD metafile all boundaries used in the simulation system are provided by this data source. Need wheels and soft terrain modeling and simulation object model elements of \A feature of the subject of the present study, is constructed using boundary rigid wheel boundary read by the data source, the movement property of the boundary are assigned the particles of the same type. Modeling of soft ground, you need to use the boundary limited ground simulation space range, within the simulation space, with particles filled in accordance with a certain pattern. Analytical expression of the two-dimensional particles are transformed by the equation of a circle from in this article, the particle distribution wheel rim, tires, soil three categories, is to determine the composition of the entire simulation system modeling of the wheels and the ground, the actual the geometric parameters of all the particles or boundary. The resilient wheel is a rim particles and several layers of tire particles, multi-layered tire model is to be completed on the basis of the monolayer model. Points based on ground modeling method in accordance with the law of the soil particle size distribution, particle size uniform model based on particle size uniform distribution model, based on the normal distribution model of the particle size three. The cyclic boundary ground-based modeling, the calculation model implemented in the motion of the system, this model to ensure that the wheels are always interacts with the ground. 3 wheels with soft ground contact role calculate the particle trajectory, we must first calculate the force of the particles, which required to contact model. Corresponding constitutive relations of two dispersion unit different categories according to the model, we will contact model M1-M6 divided into these six types: M1 mechanical calculations for rim particles and tire particles; M2 mechanical calculations between the two tire particles; M3 is used tire particles and soil particles between mechanics; M4 mechanical calculations for rim particles and soil particles; M5 for mechanical calculations between the two soil particles; M6 for mechanics between the particles and the boundary. Different contact models using different mechanical formula to derive the interaction force between the two units. \Calculate the motion of the particles, followed force → acceleration → → displacement speed calculation process, determined in accordance with the laws of motion of classical mechanics, particles or boundary trajectory at each time step. The simulation system of the main function module is within the provisions of simulation time, calculated the movement of all of modeling particles or boundary changes, and simulation of real-time data entry the external simulation files for future use. According to the different external driving action is applied to the pair of wheels, the wheel is divided into the driving wheel and the passive wheel capstan is given torque, the driven pulley is given force, whether or passive capstan wheel, the wheel contact with the ground effect of calculation process is consistent. Simulation software needs analysis and design of the system requirements analysis process, and never needs of the customer first, measure the success of the most important criteria to the satisfaction of the customers as to the needs of users as a starting point, Complete the functional requirements and performance requirements of the system. The main function of the system can be implemented: the simulation object selection, the simulation object physical parameters set set, wheels and ground modeling, simulation object mechanics parameters set simulation environment parameter settings, scrolling simulation wheels on the ground by the force, the simulation results demonstration, simulation results are stored. The performance of the system, the most important is the efficiency of the implementation, to reduce the time complexity of the program, this article has to do more work and achieved certain results. Because the system is based on MFC-platform development, design and implementation phase, the need to make the unit module compatible with the system theme, to ensure the security of the program as a whole, robustness, scalability. Testing of the software products, mainly based on unit testing to ensure the accuracy of the function of each module, on the basis of the unit test, complete integration testing to ensure that the simulation of the system to meet the needs of users on wheels - ground interaction. Limited of limited knowledge of the simulation system there are a lot of inadequacies need further improvement in the efficiency of the implementation, interface design, model parameter selection.

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