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To reduce dependence on petroleum resources and pollution to the natural environment, electric vehicles as new energy vehicles have become the focus of various original equipment manufacturers and component companies. At the same time, the NVH performance of electric vehicles is the focus of attention of automobile companies, and higher requirements are placed on sound-proof packaging, which is an important part of reducing automobile noise. Compared with traditional internal combustion engine vehicles, the biggest difference between electric vehicles (EV) is their electric drive system. High-frequency noise is generated when the electric motor is used as a power device. When there is no engine noise, the problem of electric drive noise is more obvious. Generally, an sound package is used to block the transmission path of noise. Therefore, an sound package is selected to cover the electric motor to reduce the impact of noise on the interior of the vehicle.

The researches indicate that rational design of membrane-type acoustic metamaterial (MAM) can make it have a high sound transmission loss (STL) at the anti-resonant frequency. Based on the principle of local resonance of acoustic metamaterials, this paper studied the coupling interactions between sound field and vibration modes, and designed four lightweight MAM structural units with different distributed harmonic oscillators, and then the anti-resonant behaviors of different units within the low frequency were gradually analyzed. The regulation mechanism of continuous polymorphic anti-resonance modes on broadening STL bandwidth was further revealed, and the STL characteristics have been verified within the low-frequency range by numerical simulation and experiments. The results show that the design of a single cross-shaped resonator can increase the diversity of anti-resonance modes and eliminate the node-circular-type resonance mode, then ensure the wider STL bandwidth.

Drivetrain noise from heavy off-road vehicles mainly includes engine noise, drive shaft noise, wheel-side gear noise, tire pattern noise etc. They are the main noise sources for such vehicles as they greatly influence the ride comfort of the passengers inside. This paper solved the drivetrain noise problems of a heavy off-road vehicle using the method of active noise control (ANC). Firstly, the vehicle is benchmarked and the noise problems are analyzed, while the noise sources are identified by analyzing the transmission principles of the drivetrain. Secondly, ANC strategies are made for the vehicle based on the noise profiles under various operating conditions. Thirdly, the multiple parameters for ANC are computed from simulations modeling the vehicle in idle, constant speed and acceleration respectively. Lastly, road tests are conducted using the multiple parameters from the simulations and a noise reduction of 2-4 dB can be achieved in the whole vehicle.

A flexible rebound-type acoustic metamaterial with high sound transmission loss (STL) at low frequency is proposed, which is composed of a flexible, light-weight membrane material and a sheet material - Ethylene Vinyl Acetate Copolymer (EVA) with uneven distributed circular holes. STL was analyzed by using both computer aided engineering (CAE) calculations and experimental verifications, which depict good results in the consistency between each other. An obvious sound insulation peak exists in the low frequency band, and the STL peak mechanism is the rebound-effect of the membrane surface, which is proved through finite element analysis (FEA) under single frequency excitation. Then the variation of the STL peak is studied by changing the structure parameters and material parameters of the metamaterial, providing a method to design the metamaterial with high sound insulation in a specified frequency range.

The control strategy design of vehicle active noise control (ANC) relies too much on experiment experience, which costs a lot to gather mass data and the experimental results lack representation. To solve these problems, a new control strategy optimization method based on the genetic algorithm is proposed. First, a vehicle cabin sound field simulation model is built by sound transfer function. Based on the filtered-X Least Mean Squares (FX-LMS) algorithm and the vehicle cabin sound field simulation model, a vehicle ANC simulation model is proposed and verified by a vehicle field test. Furthermore, the genetic algorithm is used as a strategy optimization tool to optimize an ANC control strategy parameter set based on the vehicle ANC simulation model. The optimized results provide a reference for the ANC control strategy design of the vehicle.