Study On Control Of Low Frequency Noise In The Cab Of A Passenger Car

Good car ride comfort of vehicle put forward higher requirements to acoustics environment.Effective interior noise reduction is regarded as an important goal of car design,which prompts an increasingly the study about automotive NVH(Noise,and Vibration,and Harshness)performance.This paper research the control of a economic car’s low frequency noise.The main contents,methods and results are following:(1)Using the finite element method,respectively,set up a body in white,vocal and body-cavity coupled acoustic models,white body,vocal harmonies and solid coupling model for modal analysis,understanding its dynamics,making recommendations on in-car noise to avoid resonance suppression.(2)Making sound pressure frequency response analysis and contribution analysis to the coupled acoustic models.Results showed that low frequency noise in the car plates,which can contribute to car’s roof and front floor sailed right ear acoustic response peak in 67 Hz,134Hz,162 Hz and other frequency ranges.(3)Practical principles of optimal design of plate shape optimization the contribution coefficient of roof,determine the layout of reinforcement.Results show that after the optimized design,the driver’s right ear noise for improved sound pressure drop of the 67 Hz peak as 6.27 d B.134 Hz peak sound pressure drop at 4.1dB.162 Hz peak sound pressure drop at 5.0dB.(4)In the base of car body structure optimization,the cover has a raised front floor boards with damping layer to reduce low frequency noise in the car.In order to save material,reduce the mass,the topology optimization design of the damping layer obtained the optimal layout of damping layer,and full coverage scheme to do a comparative analysis of damping.Results showed that through topology optimization design scheme,most of the frequency range sound pressure reduce 1-4dB,saving the material about 50%,and full coverage scheme similar to the optimizational effect.drivers sound pressure leve l in the right ear at 67 Hz reducing 3.1d B,134 Hz reducing 2.9dB,162 Hz reducing 3.4dB.Conclusion: by adding a rib and laying of damping measures can effectively reduce low frequency noise in the car.