# A Fast Approach to Optimize Trad Pattern Shape for Tire Noise Reduction
## 1 Introduction  
In the context of modern urbanization, an intricate transportation network serves as a symbol of progress. Convenient transportation options have greatly enriched people's daily lives. However, noise from the road traffic network spreads throughout the city and seriously affects people's work, lives, and physical and mental health. According to estimates from Environment Australia, road traffic contributes to over 70% of environmental noise pollution. Tire noise serves as a major contributor to vehicle noise and is a significant source of urban noise pollution, especially at speeds exceeding 50 km/h. According to statistics presented in [1], tire-pavement noise accounts for 75% to 90% of the total noise generated by passenger cars. In recent years, with the development of electric vehicles, people have higher requirements regarding the comfort and silence of vehicles. In the development of low-noise cars, tire are the most important because tire noise accounts for a large part of the total noise [2]. In particular, tire labels institutionalized in the EU show that tire noise is important because it can amplify overall noise levels [3, 4]. Tire noise, or tire-pavement interaction noise, is a complex phenomenon influenced by a range of factors [5], such as tread materials, tire structures [6], vehicle dynamics, road conditions, etc. Tire noise is generated by various mechanisms, which can be categorized into two main groups [7]: aero-acoustic and vibration-induced noise. In the former, the sound pressure fluctuation is caused by aerodynamic noise sources, such as aerodynamic effects. In the latter, the sound pressure fluctuation is caused by the vibration of the structure and the interaction with the surrounding air. In general, tire vibrations are regarded as the primary mechanism for generating tire-pavement noise over low- and mid-frequency ranges. These vibrations are induced by time-varying contact forces resultingfrom the road roughness and tread pattern. Two primary sources of noise can be identified: The first is related to tread pattern grooves and is known as the air pump mechanism, which arises from the variation in groove volume within the contact patch. The second is related to tread blocks and is known as the vibration mechanism, which is caused by the impact and release of tread blocks entering and leaving the contact patch. For the pattern impact mechanism, the local vibration is dominant in the attachment portion of the contact area between the tread and road surface. Evaluating and predicting tire noise has always been a challenge. Indoor and outdoor tire noise experiments, including the pass-by noise experiment, have been considered the most direct methods for investigating tire noise. However, the evaluation of tire noise through experiments is not only costly and time-consuming but also fails to provide sufficient information to the designer at the design stage [8]. In such situations, there is a preference to predict tire noise through efficient numerical analysis methods during the design stage. Analytical approaches or numerical techniques, such as the Finite Element Method [9], boundary element method [10], or computational fluid dynamics method, have become the primary means for tire noise prediction. To achieve an accurate simulation of tire noise, complex tread pattern modeling is necessary, and the simulation calculation takes a long time [11]. The tread model needs to be rebuilt every time the tread pattern is modified, which greatly increases the modeling cost. The potential health benefits of noise abatement can be found in the literature [12]. In general, tire-noise-reduction strategies can be separated into three categories [13]: noise control at the noise source, along the transmission path, and at the receiver. To mitigate tire noise, numerous attempts have been made to reduce tire-pavement interaction noise at the source and to ensure a lasting effect [14; 15; 16; 17; 18], including the implementation of noise barriers or shields and quiet pavement [19; 20].