Prediction And Control Of Interior Noise In Lower Frequency For Acoustic-structural Coupling System Of Light Truck

As the majority of car users continue to put forward new and higher requirements for driving comfort, the study of vehicle NVH performance is becoming more and more in-depth in automotive engineering field. Since light truck always drives on poor road conditions and its work environment is complex, the passenger compartment produces strong vibration and noise on the impact of all the excitation sources, and the drive comfort is severely reduced. Therefore, to improve its internal acoustic environment, reduce interior noise levels, and improve driving comfort has an important engineering and practical significance.How to reduce low-frequency structure noise due to the coupling of the structure and tune is important and difficult for interior noise control. With the combination of the finite element method and acoustic-structural coupling analysis theory, the analysis was carried out on the basis of the acoustic- structure coupling system model of cab. Low-frequency structure noise was analyzed and a noise reduction program was put forward with the finite element analysis software Hyperworks and MSC.Nastran. As a result, the study improved the theory and method of predicting and controlling low-frequency structure noise.The main research works are listed as follows:According to the specific requirements and procedures of the finite element modeling, the paper established the body in white, the trimmed body, the cab tune model, and the finite element model of acoustic-structural coupling system. Based on modal analysis theory, modal computational analysis and experimental verification were carried out for the trimmed body and the cab tune model. The comparative analysis results show that natural frequency error is within the range the engineering project allowed, and the main body parts are in their own modal range, with no mode coupling occurring, and the model is established accurately, which could be used for further analysis. On this basis, modal calculation analysis was carried out for the model of acoustic-structural coupling system, its inherent structural and acoustic properties were controlled, and the foundation for structure improvement and optimization of noise reduction was laidNoise transfer function from the excitation point to the driver’s right ear was calculated and analyzed to determine the unqualified peak of sound pressure response and the corresponding frequency. Input Point Inertance and dynamic stiffness were calculated and analyzed, and the primary cause of the noise peak and the main optimization frequency were analyzed comprehensively. As to the unqualified peak frequency, modal participation factor and panel acoustic contribution for the body structure were analyzed to determine these sensitive vibration panels such as floor, roof and rear wall. The paper focused on their vibration abdomen to resize, modify the structure and pave the free damping layer. Then noise simulation calculation and experimental verification of the optimized model were carried out, The comparative analysis results show that the interior noise level is reduced effectively。...