【作者】 杨川；

【导师】 于德介；

【作者基本信息】 湖南大学 ， 机械工程， 2010， 硕士

【摘要】 汽车关门声音的品质直接影响到顾客决定是否购买该车。影响关门声音的因素有很多,主要包括门锁结构,胶条结构及车门板件的结构等。目前国际上评价关门声品质的方法主要分为主观评价法和客观评价法。主观评价法是通过主观评价实验给汽车关门声品质打分,客观评价法是进行客观的声品质实验测得相关的心理学参数(响度、尖锐度等)来评价汽车关门声品质的好坏。两种方法皆是在生产出样车后来评价,并同样采用试验的方法来提高汽车关门声品质。目前缺少在前期设计阶段针对汽车关门噪声的设计方法及流程。振动板件的减振降噪设计是汽车工程的重要设计内容之一,通过减振降噪优化设计,可以在设计阶段通过对设计模型的定量修改获得理想的减振降噪效果。本文在企业合作项目“车门系统结构设计”支持下,针对影响关门声音因素之一的车门板件结构,研究建立套以减少汽车关门声音的声压级为目的,以设计修改车门板件的结构参数为手段的设计流程及方法。主要研究工作有：1)由于车门的结构参数直接影响关门声音,而结构参数中各个板件的厚度是重要且容易改变的设计参数,因此,本文以车门系统中重要的板件厚度为设计变量,以关门过程中车门系统振动动能的均方根值最小化为目标进行优化设计。建立了减小振动动能的响应面模型,用遗传算法对模型进行优化,得到了优化后的板件厚度。2)为了验证优化后板件振动辐射出的噪声小于优化前,采用基于脉冲激励的声辐射边界元法对车门系统在优化前、后的辐射的声压级进行数值分析,比较振动优化后的降噪效果。结果表明,通过优化设计对板件厚度的修改,减小振动能量,达到了降噪目的。3)企业根据实际情况制造了两辆样车,其中一辆样车车门各板件厚度与优化前一致,另一辆与本文优化后车门板件的厚度只有0.02mm的差别。为了评价样车的关门声,以一辆公认的关门声音品质较好的车为标杆车。通过实验的方法,得出了响度值、尖锐度值及A计权声压级的1／3倍频程时频图,进而评价了这两辆不同车门的样车和标杆车的关门声音品质。实验结果表明,对样车车门系统进行修改之后,响度,尖锐度及A计权声压级都比修改前有较大改善,车门修改后的样车关门声音品质基本达到了标杆车的水平,证明了本文提出的针对汽车关门降噪的结构优化设计流程的可行性与正确性。更多还原

【Abstract】 The door-slamming sound quality of a car directly affect the decision of the customers whether to buy it. There are a lot of factors affecting the door-slamming sound quality, mainly include:lock structure, glue sstructure, the plate structure of the door and so on. At present, the sound quality evaluation methods of door-closing can be divided into subjective evaluation and objective evaluation. Through the subjective evaluation experiment, we can rate the sound quality of door slamming. After the objective evaluation experiment, the psychological parameters (loudness, sharpness) which can evaluate the soud quality of door-slamming would be obtained. Both of the subjective and objective evaluation methods are adopted after producing the sample vehicle, and based on experimental means. But we still lack the methods used before producing the sample vehicle to evaluate the sound of door slamming. The design of the noise reduction of vibrating plate already becomes an important content of automotive engineering designs. Through the optimizing design of reducing vibration and noise of the door plates, we can do some quantitative changes of the design model to achieve the desired effect of vibration and noise reduction in the design stage. Supported by the project with the enterprise cooperation "Structure Design of Door System ", this thesis established a design process and method in order to reduce the sound pressure level of door-slamming by modifying the structural parameters of the door plates. The mainly works are list as follow:1) As the thicknesses of the door plates which are among the structural parameters of door system directly affect the sound of door-slaming are important and easy to be changed, at first, we built a response surface model with the thicknesses as design variables and the objective of minimizing the root meam square of kinetic energy in the process of closing door, and then, we optimized the model by genetic algorithm, at last, we got a new set of thicknesses of the door plates after the optimization.2) In order to verify the noise radiated out from the optimized plates is less than before the optimization, we did some numerical analysises of the sound pressure level radiated out from the original plates and the optimized plates by the acoustic radiation boundary element method based on pulsed excitation, and then, we compared the noises. The results show that we achieved the noise reduction by the optimization. 3) Based on the actual situation, the enterprise produced two sample cars. One of the cars had the same thicknesses of door plates with the model before the optimization, there are only 0.2mm difference between the other one and the optimized model. In order to evaluate the sample cars’s sound quality of door-slamming, we got a car with good sound quality as the benchmark car. After make a sound quality experiment, we got the loudness, sharpness, sound pressure level with A-weighted and one-third octave to evaluate the two sample cars and the benchmark car. The experimental results show that the modified car had lower loudness, sharpness and sound pressure level with A-weighted than before, the modified car’s sound quality of door-slamming have reached the level of benchmark car, which proved the process of structural optimization described in this thesis aiming to reduce the noise of door-slamming is feasible and correct.更多还原