Study On The Tire Cavity Vibration Model And Noise Reduction

Tire cavity vibration is the resonance of the acoustic cavity inside the tire when it is excited by the road surface.An unbearable low-frequency structural noise typically in the range of 200-260 Hz,which is called tire cavity resonance noise,will be caused in the cab by the vibration transmitted from the tire acoustic cavity.With the continuous optimization of passenger cars and engines over recent years,tire cavity resonance noise has become a prominent issue affecting vehicle NVH performance and needs to be urgently resolved,especially for the new energy vehicles.However,there is still a lack of a theoretical model that accurately reflects the mechanism of its production and transmission.The influence of rolling speed remains to be clarified.At the same time,there is also an urgent need for reasonable and effective noise reduction methods.Theoretical and experimental research have been carried out on the above issues,mainly including the following innovative results:(1)A unified method for the vibration characteristic of cylindrical shells on elastic foundation is proposed,and the possible problem of missing solutions in the general practice is solved;Solutions to the natural frequency and mode shape are given,and the influence of internal pressure and elastic foundation on vibration characteristics was also analyzed,laying a theoretical foundation for the establishment of tire-cavity coupling model.(2)A new kind of tire-cavity coupling model was established to greatly improve the accuracy and efficiency,which solved the bottleneck problems of the existing models: the composite properties of the tire were not taken into consideration;the influence of axial vibration of the tire and elastic supporting of sidewall was not considered;and there are large errors.The proposed model is composed of two cylindrical shells with different diameters and supporting springs evenly distributed at both ends.The annular cavity surrounded by the cylindrical shell and the spring represents the tire cavity,and the outer flexible cylindrical shell adopts a laminated composite material structure,which was used to simulate the tread consisting mainly of rubber and belts.The inner rigid cylindrical shell is used to represent the wheel,and the spring is used to represent the sidewall.Results obtained through the theoretical model agree well with the experimental results,which can be used to gain better insight to the mechanism of tire cavity resonance noise.(3)The influence of the rolling speed on the vibration characteristic of the coupling model is analyzed,clarifying the mechanism and basic laws of frequency bifurcation of tire cavity vibration in rolling state.Furthermore,combining with the pseudo excitation method,a complete analysis method from the road excitation to the response of the spindle was established,and the tire cavity resonance noise under different road conditions and different speeds can be predicted and analyzed.The theoretical method has been verified with the experimental results.The results show that this method can reflect the main dynamic characteristics of the tire in the rolling state,further expanding the tire-cavity coupling model,and also makes the application of the model closer to the engineering practice.(4)Based on the theoretical model,a sensitivity analysis method of factors influencing tire cavity vibration was proposed.Combining finite element method with experimental method,the noise reduction design of tires and the noise reduction effect of sound-absorbing materials were studied.The basic idea of tire noise reduction design was developed,a kind of sound-absorbing material with a good effect of noise reduction was found,a quantitative analysis method was provided for the design of tires with low cavity noise,and the existing method for noise reduction of sound-absorbing materials was also improved.The above research has further revealed the mechanism of tire cavity resonance noise theoretically,providing a quantitative tool for the analysis of tire cavity resonance noise and the guidance for the noise reduction design of tires,and is helpful for solving the problem of tire cavity resonance noise and improving the vehicle NVH.