轻型客车结构和声学特性分析与优化

发布时间：2017-12-31 13:38

本文关键词：轻型客车结构和声学特性分析与优化　出处：《江苏大学》2016年硕士论文　论文类型：学位论文

【摘要】：车内低频结构噪声直接影响着驾乘人员的乘坐舒适性,妥善缓解车内低频结构噪声对车内驾乘人员造成的感官影响,改善车辆乘坐舒适性,是汽车企业提高其市场竞争力及其产品升级的重要方向。论文以某轻型客车为研究对象,首先运用模态灵敏度分析与结构优化的方法对车身结构的模态特性进行了预测与优化改进;然后对车内噪声进行了分析,基于板件声学贡献量分析结果,对车内声压影响较大的顶棚、前地板与后地板进行了优化改进,降低了车内低频噪声。论文主要的研究工作与结论包括:1,在某轻型客车几何模型的基础上建立了白车身有限元模型和车室声腔有限元模型,分别进行了模态分析,得到了结构和声腔的模态固有频率与振型,并通过对比结构有限元模态和试验模态,验证了所建立的车身结构有限元模型是可信的。根据车身结构模态计算结果,发现客车白车身的前三阶模态固有频率过低,为保证客车具有良好的平顺性,应使客车低阶模态固有频率避开与人体产生共振的频率范围。2,针对白车身结构前三阶模态固有频率过低的问题,对车身进行灵敏度分析,得到了前三阶模态固有频率与车身质量对各板件的灵敏度,在尽量不增加车身质量的情况下,运用形貌优化和零部件厚度调整的措施对车身结构进行改进,提高了车身前三阶模态固有频率,有效地避开了人体敏感频率范围4-12.5Hz,而车身质量没有明显增加。3,建立了客车的声固耦合有限元模型,在此基础以发动机激励为例对车内耦合噪声进行分析,通过对车内目标场点的声压级曲线图分析,得到了声压峰值与声压峰值对应的峰值频率。4,对车身进行板件声学贡献量分析,得出了各个板件在峰值频率下对各个场点的贡献系数,发现车身顶棚、前地板与后地板对车内各个场点的低频噪声贡献量较大,为车身结构优化与修改提供了依据与指导。通过形貌优化的措施对顶棚、前地板与后地板进行了结构改进。通过优化前后声压级曲线对比,各场点在最大噪声峰值频率处的声压值均下降了3-5dB(A),有效地改善了客车内部的声学环境,提高了驾乘人员的乘坐舒适性。
[Abstract]:The low frequency structural noise in the vehicle directly affects the ride comfort of the driver, and properly alleviates the sensory impact of the low frequency structure noise on the driver in the vehicle, and improves the ride comfort of the vehicle. It is an important direction for automobile enterprises to improve their market competitiveness and upgrade their products. First, modal sensitivity analysis and structural optimization are used to predict and optimize the modal characteristics of body structure. Then the interior noise of the vehicle is analyzed. Based on the results of the analysis of the acoustic contribution of the plate, the roof, front floor and rear floor are optimized and improved for the roof, the front floor and the rear floor, which have a great influence on the sound pressure of the vehicle. The main research work and conclusion include: 1. Based on the geometric model of a light passenger car, the finite element model of white body and the finite element model of chamber sound cavity are established. The modal analysis is carried out, and the modal natural frequencies and modes of the structure and the cavity are obtained, and the finite element modal and the experimental mode of the structure are compared. It is proved that the finite element model of the body structure is credible. According to the results of the modal calculation of the body structure, it is found that the first three modes of the bus body are too low, so that the passenger car has good ride comfort. In order to avoid the frequency range of resonance with human body, the natural frequency of low order mode of passenger car should be avoided. Aiming at the problem of too low natural frequency of the first three modes of the white body structure, the sensitivity analysis of the body should be carried out. The sensitivity of the first three modes natural frequency and body mass to each plate is obtained. The shape optimization and component thickness adjustment are used to improve the body structure without increasing the body mass as much as possible. The natural frequency of the first three modes of the body is improved, and the sensitive frequency range of human body is effectively avoided, but the mass of the body does not increase obviously. 3. The finite element model of acousto-solid coupling of passenger car is established. Taking engine excitation as an example, the coupling noise in the vehicle is analyzed, and the corresponding peak frequency of sound pressure peak and sound pressure peak is obtained by analyzing the sound pressure level curve of the target field point in the vehicle. According to the analysis of the acoustic contribution of the body, the contribution coefficient of each plate to each field point at the peak frequency is obtained, and the roof of the body is found. The front floor and rear floor contribute a lot to the low frequency noise of each spot in the vehicle, which provides the basis and guidance for the optimization and modification of the body structure. The structure of the front floor and the back floor were improved. By comparing the sound pressure level curves before and after optimization, the sound pressure values at the peak frequency of the maximum noise at each field point were all reduced by 3 to 5 dBU A). The acoustical environment inside the passenger car is improved effectively and the ride comfort of the driver is improved.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U461.4

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