# A Fast Approach to Optimize Trad Pattern Shape for Tire Noise Reduction
## 1 Introduction
The former reduces noise mainly through sound absorption and sound insulation, and the latter mainly reduces noise by reducing the reflection and propagation of sound on the pavement, as well as by reducing the generation of sound. Compared with noise barriers or shields, quiet pavement might not be a viable option to mitigate traffic noise because the pavement can wear out and become louder with time [14]. Furthermore, the construction and maintenance costs of pavement are also quite expensive. Thus, controlling tire-pavement interaction noise at its source, i.e., quiet tires, can be a more economical and effective approach. In the tire industry, a number of design concepts to reduce tire noise have been considered [21; 22; 23], including tire tread [24], tread pattern, tire cavity [25], tire structure, and rims [26]. However, sound-absorbing materials attached inside the tire cavity to reduce the cavity resonance noise might be the most successful so far. Among all of the strategies for reducing tire noise, the tread pattern is considered to be the easiest to modify [27]. In the literature [28], two approaches have been proposed to reduce the tire noise related to the tread pattern. One is meant to disperse tire noise energy over a broad frequency range, which can be achieved by using variable pitches and randomly arranging them around the tire [16; 29; 30]. The second method reduces the exciting force caused by the discontinuity of the tread block in the direction of tire rotation. In this case, engineers have to modify the pattern's geometric design. Nevertheless, the automatic generation of a pattern that fulfills the performance requirements poses a significant challenge. The mathematical representation of the tread pattern is challenging due to its complex structure. In [31], a method was developed to parameterize the pattern geometry, involving over 11 parameters to describe the pattern in detail. Recently, researchers have explored the interaction between the optimal tire profile and tread pattern design by employing the basis vector method [32]. An advantage of the basis vector method lies in its capability to effectively describe complex geometric structures using only a few parameters. Another advantage of this method is that the design engineers can incorporate their design ideas into the basis vector shape [33]. The capability to predict and reduce tread pattern noise will help improve tread pattern design. The contribution of this study is the development of a new optimization method related to tread patterns for tire noise reduction. The rest of this paper is organized as follows: Section 2 reviews the mechanism of tire noise, and a pattern impact noise prediction model based on pitch noise theory [34] is established. Section 3 describes the details of the synthesis method of pattern shape based on the basis vector method. Section 4 outlines the optimization process based on the genetic algorithm. The prediction method is verified by semi-anechoic chamber and pass-by noise experiments. Then, the optimization results of the tread pattern and leading edge are discussed in Section 5. Section 6 concludes the paper.