基于PolyMAX的声固耦合模态试验研究

白车身的结构模态频率和模态振型反映了汽车车身结构的固有特性,对车内噪声有重要影响。车内空腔跟车身结构一样,同样拥有模态频率和模态振型。采用LMS数据采集系统对某国产SUV进行车内空腔声学模态试验。首先基于传声器阵列的方法获取响应点的信号,然后利用PolyMAX方法提取声学模态频率及振型。将声学模态频率与白车身结构模态频率进行对比分析,结果表明：车内空腔的第一、二阶声学模态分别跟白车身的第四、十阶结构模态有很强的耦合。最后通过实车测试验证了声固耦合共振时低频轰鸣的存在。可以在关键部件增加板厚、顶盖和地板附加阻尼层、顶盖加加强筋等方式改变车身结构的局部模态来破坏车身结构模态和声腔模态的强耦合状态,降低车内的低频轰鸣声     

Multidisciplinary optimization of car bodies

Rising complexity of industrial development in the automotive industry is leading to a higher degree of interdisciplinarity, which is especially true in the virtual design area. New methods and solution procedures have to be evaluated and integrated in the overall process. For example, in car body design process, a new topic emerged recently: the multidisciplinary optimization of car bodies with respect to crash and NVH (noise, vibration, and harshness). Because rigorous evaluation of appropriate numerical algorithms is still missing, an intense study was realized at the research center of BMW. The results are summarized in this article. Four benchmarks have been studied: (a) a full vehicle model for NVH analysis, (b) a simplified multidisciplinary problem with a single crash case and linear statics and dynamics, (c) a lateral impact problem for multi-criteria optimization, and finally, (d) a small shape optimization problem was included to demonstrate the potential of transferring the results to the more complex problem of optimizations based on real changes in the shape of the structures. Because response surface methods have already been discussed in the literature and because of their failure in certain industrial cases, the focus was set on the evaluation of stochastic algorithms: simulated annealing, genetic and evolutionary algorithms were tested. Finally, a complete industrial multidisciplinary example from the current development process was studied for the validation of the results.     

两用燃料汽车的振动噪声特性

试验研究了捷达LPG／汽油两用燃料汽车的振动噪声特性。主要测量了发动机缸体和座椅的振动情况，对比分析了匀速和加速时燃用汽油和LPG的噪声特性。试验结果表明：两用燃料汽车使用LPG时，发动机机体振动幅值比使用汽油时小；而加速过程中，在较低转速下使用汽油噪声较大，在较高转速下使用LPG噪声较大。     

A material and gauge thickness sensitivity analysis on the NVH and crashworthiness of automotive instrument panel support

This paper provides a finite element analysis of the effects of using alternative materials and gauge thickness on the weight and structural performance of the VN127 instrument panel support. Two types of analyses were performed, NVH and crashworthiness. The NVH analysis was used to determine the structure’s natural frequencies, whereas the crashworthiness analysis was used to examine the structure’s crash behavior under two different impact conditions. The materials used in this study included mild steel, aluminum and magnesium alloys. The thickness of the structure was varied from 0% to 40%, in increments of 10%. The results of different models were compared with the baseline model, i.e., the mild steel model with nominal thickness. It was found that by replacing mild steel with aluminum alloys, and increasing the gauge thickness of the structure by 40%, the NVH and crashworthiness performance of the structure was equivalent to the baseline model.     

车辆变速箱啸叫噪声测试诊断

在汽车NVH研究范围内,动力总成相关的噪声振动一直是研究的一个重要方面,同时也一直是研究的一个困难课题.其原因为该噪声振动往往必须通过正向的动力总成相关部件研究及设计修改来确诊原因并且最终解决问题.通过一个实际案例介绍如何使用阶次分析原理和传递路径分析方法对车辆变速箱的齿轮啸叫噪声进行测量及诊断,根据文中的测试诊断结果...     

基于刚柔耦合模型的悬架NVH性能研究

使用有限元软件分析了橡胶衬套对悬架NVH性能的影响。柔化其他悬架部件,建立了多体动力学刚柔耦合模型。通过试验设计(DOE)分析了橡胶衬套刚度对悬架NVH性能的灵敏度并进行了优化。通过对比优化前后仿真结果,可以看出悬架中高频NVH性能得到了改善。将模型仿真与道路模拟机测试结果进行对比,验证了模型的准确性。     

某型汽车变速箱的振动噪声分析

针对某型新能源车用两挡变速箱的振动噪声问题,通过NVH试验、理论计算、仿真分析相结合的方法分析引起振动噪声的根源。首先,基于整车NVH主观评价的结果,通过NVH试验采集变速箱振动信号并进行数据处理分析;其次,通过计算变速箱各齿轮副啮合频率及特征阶次,判断各阶噪声的产生位置;最后,使用ANSYS WORKBENCH软件对变速箱壳体进行模态分析进而得出前20阶固有频率,结合试验数据及啮合频率判断产生各阶噪声的共振频率点。基于对变速箱振动噪声的分析,为下一步制定整改措施提供了必要条件。     

某轿车前副车架模态分析与优化

以"某车型前副车架"为研究对象,利用Hyper works 11.0软件对该副车架结构进行了自由模态分析、 全约束模态分析和半刚性约束模态分析,针对分析结果与实际整车下的模态值比较,提出了较为合理的边界约束条件下的模态分析方法,以更加接近副车架在整车下的实际状态值.同时由于该副车架整车实测模态值偏低,与发动机常用转速下...     

汽车变速器降噪分析及控制方法研究

汽车结构振动噪声及舒适性已成为评价动力机械产品的重要指标,变速器是汽车传动系统的主要构成部分,变速器的噪声和振动对性能对提高整车的NVH性能极其重要.对变速器的主被动降噪设计进行分析,为国内汽车工程领域提高变速器的NVH性能提供一定的信息和指导.     

某SRV白车身动态性能研究及工程治理

以某SRV车为研究对象,针对其整车振动过大问题,利用CAE技术对其白车身动态性能进行研究,以期改善该sRV整车NVH性能.研究探明了其动态性能较为薄弱的环节,并据此对白车身提出改进设计方案.测试结果表明,将改进后的白车身搭载到整车上以后,整车噪声可降低5 dB,显著提高了整车NVH性能.