Research On Prediction And Control Of Vehicle Inner Noise In Full Frequency Band

The passenger's drive-ride confort and the veichle's market competitiveness are increasingly affected by the interior noise. The interior noise confort is affected by body structure-borne noise, airborne noise within tens Hz to several k Hz or even higher full-range frequency domain. For a long time, the prediction and optimization control of interior noise mainly concentrated in the low range or high frequency range. It's important to carry out the prediction and control of interior noise within the full-range frequency domain.For interior noise prediction and control within full-range frequency domain, FE,FE-SEA and SEA three kinds of methods based on VA one are adopted in this peper. Considering body vibration excitation, the engine sound radiation excitation, outside wind excitation and basic noise control treatment, this paper studies the interior noise response in the full-range frequency band of 20 Hz to 8000 Hz. After the contribution analysis, the inerior noise is optimized based on RSM in this paper. The main work of this paper is as follows:(1)Summary of the interior noise prediction and optimization methods progress at home and abroad, pointing out the necessity of full-band interior noise prediction and control.(2)For lower frequency band interior noise prediction, using FE method, the SPL response of driver's right ear and right-rear passenger's left ear in the low frequency range of 20Hz~200Hz were predicted. The results show that: the acoustic modal have a greater impact on interior noise peak response, basic NCT can attenuate the body vibration and interior noise in the low frequency band.(3)For middle frequency band interior noise prediction, using FE-SEA method, the SPL response of driver's head cavity in the middle frequency range of 200 Hz ~ 500 Hz was predicted. The study shows that: the peak mutant of body excitation, resulting in a peak response of interior noise.(4)For higher frequency band interior noise prediction, using SEA method, the SPL response of driver's head cavity in the middle frequency range of 500Hz~8000Hz established was predicted. The results show that: basic NCT can attenuate the interior noise by 3~7d B above the frequency band of 800 Hz.(5)For the optimization and control of the interior noise, interior noise response was calculated using SEA, within 200Hz~8000Hz. On the basis of the plate contribution analysis, an RSM approximate model of the driver's head cavity SPL response was established by using DOE. Based on the approximate model, Downhill Simplex Method was adopted to optimize the thikness of firewall's NCT. The results show that this optimization method makes the maximum sound pressure reduce 0.9865 dB, band overall sound pressure reduce 0.7282 dB. Based on this, other few kinds of optimization methods were adopted to control the interior noise, summed up the conclusion of that compared to the NCT parameter optimization, NCT configuration and optimization of the body structure are more conducive to interior noise control.