Study On Modal Characteristics Of Rolling Tires

Tire is one of the most important components on the car, and it is also the only part that contacts with the road surface. Tire vibration and noise of tires have a direct effect on the driving smoothness, ride comfort and vehicle noise. It has aroused extensive concern among tyre manufacturers and OEMs that how to reduce the vibration and noise of tires. They have put forward various requirements on selection and matching of tires. For example, some OEMs require tire manufacturers to provide tire modal parameters. Therefore, the study on tire modal and vibration transmission characteristics is particularly important, and it is also significant for the reasonable design of tires.Due to the limitations of test condition, current studies are mostly about tire static modal characteristics. However, the crux here is that there are significant differences of modal characteristics between rolling and static tires. And the research on modal characteristics of rolling tires is of great significance for predicting the dynamic characteristics of tires. Therefore, it is imperative to research the modal characteristics of rolling tires in spite of enormous challenges on the test.In recent years, finite element method has got continuous development and been widely applied to the tire research. Finite element simulation technology can simulate many tests which can not be conducted in the lab or real situation, and it also can reduce the difficulties of scientific research and save the cost and time. Combining the finite element method with LMS equipment, the thesis studies the influencing rule and mechanism of all kinds of factors on tire modal parameters. Through the calculation of resonant frequency of rolling tires, the thesis has a good understanding about the influencing rule and mechanism of revolving speed on resonant frequency, and concludes the modal characteristics of rolling tires.Specifically, the main contributions of this thesis are listed as follows:1. Have a good research of the history, current situation and significance of tire vibration. The thesis presents in detail several different tire vibration classification methods, the method and equipment of tire vibration test, the calculation model of tire natural frequency and vibration mode, and research achievements at home and abroad.2. Make an analysis of tire experimental model. The thesis details the theoretical foundation of experimental modal analysis and the whole test process. By effective organization of tire modal test, the thesis studies that how the factors influence tire modal parameters, which include supporting way, the direction of excitation and vibration picking, boundary conditions, inflation pressure and load, and concludes transfer function curves of tire vibration.3. Calculate modal analysis by means of tire finite element model. This paper establishes a relatively accurate finite element model of tire, and makes a detailed introduction on the process of establishing model. Based on the model, it has calculated the natural frequency and vibration mode of tire, and classified the tire modes with indices notation method. And the thesis studies the influencing rule and mechanism of charge pressure, load and internal material parameters of tires on natural frequency, and static modal characteristics of tires with the method of the tire finite element model.4. Make the calculating modal analysis of rolling tires. This part is based on the progressive research idea to make an analysis of the tire modal characteristics. The effect of inertia force of the tires in rolling motion is reinforced, therefore the thesis concludes the influencing rule and mechanism of revolving speed on resonant frequency. Due to the tire structure and material haven’t been changed in the process of rolling, tire characteristics under static state can also be applied to rolling tires. Based on the results, the thesis concludes the modal characteristics of rolling tires.