The Improvement Of The In-plane UniTire Durability Model And The Realization In CarSim

Supervisor:Prof. Konghui Guo, Academician of Chinese Academy of EngineeringThe UniTire1.0 and UniTire2.0, which is the handling tire model widely used under the low-frequency, had been linked with the typical dynamic software. To demonstrate the structural reliability, the vehicle always need to pass some typical road tests, such as running over the road with the pothole, the curb, the cobblestone and the railway intersection. The interaction of the pavement and the vehicle with different speed will bring the multi-direction deformation and vibration of the tire. Generally speaking, in such case the handling tire model will no longer be suitable for the simulation. A boffin has proposed a new model called in-plane UniTire Durability tire model in his dissertation. It is able to exhibit the vibration of the belt under the in-plane excitation less than 100Hz. It is also able to calculate the dynamic response of the tire under the uneven road and medium frequency excitation. If combined with the vehicle multi-body dynamic model, it will help to get the stress distribution on the parts of the car body, chassis and the other systems much more quickly and accurately. It will supply the precise boundary conditions for the structure analyses of each part. It will decrease the development cycle and reduce the expense of development and increase the competitive power of the product. Therefore, two issues related to the promotion of the model were carried out within the thesis, one is the calculating method of two-dimension effective road considered with the enveloping of the pneumatic tire and the other is the embedding of the in-plane UniTire Durability tire model into the dynamic software, CarSim. This thesis is composed of five chapters.The first chapter is the exordium. The research progressing about the tire dynamic model for vehicle dynamic simulation under the uneven road and the research background of this thesis is introduced. The content of this paper is summarized finally.Some basic properties about the in-plane UniTire Durability tire model are discussed in the second chapter. Firstly, the typical parameters and properties about the pneumatic tire used in this paper are introduced. A whole pneumatic tire is composed of the belt, the tread, the sidewall, and tire bead. The mass of these parts is distributed to the belt-ring and the rim. The mass and rotation inertia of these segments is estimated. Next, the theories of the simple UniTire Durability model (only with the vertical DOF) and the in-plane UniTire Durability tire model and the UniTire slip model are discussed. The belt-ring shows the inertia of the tire under the high frequency. The tire sidewall with pressured air is modeled as the spring and damper along vertical, longitudinal and circumferential orientation to express the vibration properties of the belt .The vertical contact spring shows the large deformation of the tire when contacting with the road. The relaxation slip model calculates the tangential force result from the motion input of the belt-ring. When the tire runs over the short wavelength unevenness, the quasi-static response of the tire is converted into effective road profile. That shows the enveloping characteristics of the tire. It will be the equivalent excitation of the single-point contact dynamic model.The quasi-static response of the pneumatic tire running over the typical unevenness is analyzed in the third chapter. It is considered that the tire and pavement are single-point contacted with each other in the UniTire Durability model. The quasi-static response of the tire running over the actual pavement will be the input of UniTire Durability model. When the excitation of the pavement affects the tire, it will be filtered because of the enveloping properties of the tire. First of all, the experiment methods about the tire enveloping are introduced. Some effective road on which the tire pass the typical obstacle are found by analyzing the experimental data about the tire enveloping. The "Curve-Translation-Superposition", the "Two-Point Follower", and the "Tandem Egg" techniques are summarized in the third section. They are used to calculate the effective pavement in this thesis. If it comes across the short wavelength unevenness, the discrete signals from time-domain or space domain instead of the actual road will be converted into binary image. A basic image defined by the basic parameters of the tire shows the tire's geometry characteristics, which is used for morphology filtering. The two-dimension effective road of the arbitrary short wavelength unevenness could be calculated by the morphology filtering, the "Tandem Egg" and the "Two-Point Follower" techniques. The simulations have been compared with the experiments. The outcome demonstrates that this calculating method is feasible, accurate and robust. This method is able to calculate the two-dimension effective road. It can avoid abundant experiments and the parameter identification for the fundamental curves. The calculating speed is higher than the traditional flexibility ring tire model and the precision is enough. It will be used in three-dimensional pavement and real-time calculation.In chapter four, the in-plane UniTire Durability model is connected to Carsim through the Simulink interface, which is also used for the evaluation of the in-plane UniTire Durability model beforehand. It has been verified with the simulations and some experiments. It is very convenient to build model, debug and link of the CarSim with the MatLab/Simulink. Firstly, the in-plane UniTire Durability model summarized in the second chapter and the calculating methods of the two-dimensional effective road introduced in the third chapter has been connected with the Simulink in order to build a simple UniTire Durability tire model test platform. The simulating inputs according to the actual experiments are instituted and the simulations under these behaviors are compared with the experimental data. Next, the tire model verified in the Simulink has been joined to the CarSim. The simulations of single wheel and the whole vehicle running over the typical obstacle are realized. The linking of the model with the software is successful. It is accurate and robust in the applicability of this model (The excitation of the road in-plane less than 100Hz in vertical and 80Hz in longitudinal.).The fifth chapter is the summary and conclusion. And the recommendations for further development of the study are also put forward.The main creative work of this thesis lies in the following: dealing with the two-dimension unevenness, it makes reference to the "Two-Point Follower" and the "Tandem Egg" techniques discovered by Pacejka's team. At the same time, it also introduces the binary image and morphology filtering which are used in the image processing usually. So it has realized the calculation of the two-dimension effective road for the two-dimension arbitrary short wavelength unevenness. The test bench for the in-plane UniTire Durability tire model is built in Simulink. The linking work of the in-plane UniTire Durability tire model with the whole vehicle dynamic model in the CarSim has been realized. The simulation of the whole vehicle running over the typical short wavelength unevenness is successful.