چكيده به لاتين
Today, the increase in traffic volume has conduced to an increase in road noise and noise pollution. In this regard, the automobile tire plays a significant role in producing this pollution. The most important mechanism of producing tire noise is the impact and separation of tread blocks on the ground. Thus the pattern of the tread pitches is an important parameter in the tire noise. In this study, a Tire Model 175 / 70R13 manufactured by IranTire company was investigated for noise reduction via pitch pattern optimization. In this study, after introducing tire noise, its mechanisms of creation and transmission, and examining the used models in tire noise analysis, the finite element method was chosen to calculate tire noise. One of the main challenges in solving this problem is to create models of the tire with different pitch pattern in order to achieve an optimal pattern, because modeling this number of patterns by using drawing software is too time-consuming and impractical. Moreover, meshing these models for solving at finite element softwares requires consuming much time and precision. In this research, an algorithm is presented for tire meshing and modeling which is capable to generate tires with various pitch patterns in a meshed form. After modeling the tire and determining the properties of its layers, environmental and operating conditions were applied to the tire in COMSOL according to R117 standard and the sound pressure level for the studied tire was achieved 73.4 dBA. In the following, genetic algorithm is used to optimize the pitch pattern and the goal is to achieve a pattern that produces the lowest level of noise. In the genetic algorithm The objective function is calculated using the Fourier transform method and eventualy the optimum pitch pattern was achived. Then, in order to verify the results of the simulation in the COMSOL and the optimization in the MATLAB, the Pass-By test was performed according to R117 standard on the studied tire and sound pressure level was measured 72.1dBA. The results of which were in good agreement with the simulation results. Then, by modeling the tire based on the obtained pattern from the optimization and repeating the simulation process in the COMSOL, the sound pressure level was calculated for the optimal model and results showed 1.8dBA reduction in sound pressure level. In addition, in this research a software was developed which able to create meshed models of any tire, It can also calculate the harmonic spectrum for each tire and provide the optimal pitch pattern.
