车辆内部异常噪声的传递途径研究

针对某车型开发过程中车内异常噪声问题进行了试验分析,确定了发动机支承为该车辆车内异常噪声的主要来源,识别出异常噪声向车内传递的传递途径,并对发动机支承进行了优化.试验结果表明,优化支承使车内右后座位处500 Hz附近的声压敏感度峰值降为原来的50%;倍频带噪声级下降了约3 dB;主观评价显示该异常噪声得到了明显改善.     

黄海BOB城市客车的车身降噪

噪声是衡量客车制造质量的重要指标,降噪已成为国内外客车行业研究的重大课题。在此综合论述了黄海BOB客车在车身结构设计中综合运用吸声、隔声和阻尼减振技术控制车内噪声的基本思路和具体方法。     

某车后排加速轰鸣音改善研究

本文首先介绍了单自由度粘性阻尼系统动刚度理论和计算方法,提出通过增加结构局部刚度减少车内噪音的观点,并以某车为例,通过试验发现该车后排轰鸣音问题,利用CAE分析方法找到导致该轰鸣音问题的原因,提出在排气管中通道两侧安装加强板以增加局部刚度的几种NVH优化方案,通过CAE方法分析各种优化方案的动刚度和固有频率,最终确定最佳方案,较好的解决了后排轰鸣音问题。     

轻型载货汽车车外噪声分析与控制

用声强扫描法对国产某轻型载货汽车车外噪声源进行了识别,确定了其车外主要噪声源。开发了材料声学特性测量系统,并对多种车用吸声、隔声材料进行了测试与分析。根据被试轻型载货汽车车外主要噪声源的特性合理地选择吸声、隔声材料和噪声控制方案,对其进行了降噪处理。通过对降噪前、后该车车外噪声进行测试分析表明,采取降噪措施后,被试车辆车外动态加速噪声由84dB(A)下降到78dB(A),能够满足国家标准GB1495—2002对该类车辆车外动态加速噪声限值的要求。     

基于A柱-后视镜车内气动噪声数值模拟与预测

针对后视镜引起的前侧窗与车内气动噪声问题,采用计算流体力学(CFD)方法对某商用车进行车外后视镜区域数值模拟和车内噪声预测的研究。稳态分析采用RANS模型中SST(Menter)k-ω模型,瞬态分析采用基于SST(Menter)k-ω的分离涡模拟(DES);通过分析后视镜侧窗区域的稳态静压力与瞬态动压力、速度和涡量云图,揭示了因A柱后视镜而产生车窗表面的湍流压力脉动的机理;同时求解瞬态流场获得两侧车窗表面湍流压力脉动载荷。采用声学FEM方法将车窗表面湍流压力脉动作为边界条件来计算气动噪声的传播,基于车内声学空间不同频率的声压级云图分布规律,说明了车内气动噪声主要集中在中低频段和声压级最大的分布区域;驾驶员左耳旁声压级曲线展示了20-2500 Hz频段内声压级变化规律。最后进行实车道路滑行测试,证实了气动噪声在车速80-110 km/h时较为明显的结论;采用CFD结合声学有限元的方法可较为准确地预测车内100-2500 Hz气动噪声的声压级,为优化后视镜、降低驾驶室内气动噪声提供仿真和试验的技术方案。     

货车座椅动态参数优化设计试验研究

对某货车座椅的固有频率、刚度及相对阻尼系数进行了测试，通过测试数据按公司要求对座椅的固有频率、刚度及阻尼三者进行优化设计，按优化设计加工出新的座椅，其载荷在500～1200N范围变化时，固有频率在2．5～2．9Hz、刚度在18．0～27．5N／mm之间变化，相对阻尼系数为0．32。该指标满足设计要求。     

基于直接CAA与SEA的汽车风噪预测与控制

本文中对某一SUV风噪的预测与控制进行研究.首先基于风洞测试进行风噪声源特性与传递路径的分析,发现泄漏噪声主要发生在500 Hz以上中高频段,车底风噪主要集中于800 Hz以下中低频段,而在外形噪声中,由车顶和四门传递的风噪的贡献大于翼子板.然后基于气动噪声直接计算法和统计能量分析对外形噪声进行仿真,并结合风洞测试分析...     

轿车车内噪声控制方法研究

本文系统阐述了控制某装备直列四缸发动机的国力的车内噪声的系统方法。首先通过试验分析确定发动机二阶振动是引起车内噪声的主要振源，识别出发动机固体振动向车内传递的传递途径，并且确定了对车内噪声有较大贡献的车身板件。在此基础上，通过对发动机、副车架悬置管的橡胶支承元件弹性特性的修改控制发动机振动向车内的传递；通过对车身顶棚结构板件的动力修改控制车身板件的振动。对改样整车的试验得到满意的降噪结果。     

Application of a sound insulation panel with ventilation holes to the engine under-cover

Reducing engine noise is one of the most important issues in lowering vehicle exterior noise. An engine under-cover is one effective measure for reducing engine noise. However, the size of the under-cover is limited by the need to ensure sufficient engine cooling performance. To solve this problem, a new sound insulation panel with ventilation holes was developed and applied to the engine under-cover. The panel accomplishes sound insulation by controlling the acoustic anti-resonance of sound waves transmitted through the ventilation holes. This paper describes guidelines for applying the panel to the engine under-cover from the viewpoints of acoustics and fluid dynamics.     

高架公路新型泡沫铝隔音屏的研究

利用东北大学生产的泡沫铝材料制作了新型泡沫铝隔音屏,研究了新型泡沫铝隔音屏合理结构,测试了新型泡沫铝隔音屏的隔音效果.结果表明:新型泡沫铝隔音屏在低频段具有良好的隔音效果,可将环境噪音降低20～30dB,表明其是一种非常先进的隔音屏,具有很好的应用前景.     

重型汽车噪声源识别及其控制研究

利用声强法和声全息法各自的优点,对重型车车外噪声源进行综合识别,得到其主要的噪声源及其主要的噪声频段。在进行车外噪声控制过程中,选用优化的吸隔声结构能够降低噪声2.5dB(A)以上,降噪方案对发动机、整车的其他性能影响在允许范围之内,且噪声控制成本少于整车的0.4%。     

Model development and experimental research on an air spring with auxiliary reservoir

This paper focuses on the dynamic stiffness and overall equivalent damping of an air spring connected to an orifice and an auxiliary reservoir, with respect to the displacement excitation frequency, orifice area, and auxiliary reservoir volume. A theoretical model of this air spring with its auxiliary reservoir is derived by utilizing the energy conservation equation, gas state equation, and orifice flow rate equation. Simulation results from the presented model reveal that, when the air spring is subject to harmonic displacement excitation, its dynamic stiffness increases with an increase in excitation frequency and decrease in orifice area. Smaller orifice areas and lower excitation frequencies result in higher overall equivalent damping. A validation experiment is also implemented. When compared with experimental results, simulations show consistent varying trends of the dynamic stiffness and overall equivalent damping. The model developed here can correctly describe the behavior of the air spring with auxiliary reservoir, indicating that it is reasonable and feasible.     

Interior sound field refinement of a passenger car using modified panel acoustic contribution analysis

Panel acoustic contribution analysis (PACA) is a practical engineering tool for the reduction of interior structure-borne noise in passenger cars. In this study, the current PACA method has been improved for sound field refinement of the entire interior. Two new parameters, the “acoustic contribution sum” and the “total sound field contribution”, are introduced to analyze the interior sound field characterized with multiple field points and sound pressure peaks, and to evaluate the integrated acoustic contributions of auto body panels. In addition, a systematic methodology for automotive interior sound field refinement is also proposed on the basis of the modified PACA method. An example of a passenger car model demonstrates the application of the sound-field-refinement methodology and shows the advantage of using damping layers at optimum locations on the auto body. The example also shows that the modified PACA method has practical significance for refining the interior sound field and decreasing added mass in accord with the trend towards lightweight auto bodies.     

发动机声激励下的车内高频噪声分析

为研究发动机声激励下中高频噪声和整车声学包隔声性能,在VA One软件中建立整车统计能量分析模型和声学包模型,并进行基于能量的整车隔声量测试和发动机噪声采集试验,验证了整车模型的准确性.通过对驾驶员头部声腔和腿部声腔的输入能量贡献量分析,发现前围和地板是车内噪声的主要传播路径,为后续汽车声学包的优化设计和车内噪声控制提供了帮助.     

柔性约束颗粒冲击阻尼技术及应用

本文介绍了柔性约束颗粒击阻尼技术及其减振机理，并将该技术应用于薄密闭腔体壁板振动和内部噪声的控制。实验证明，该技术结构简便，控制频带宽，减振降噪效果显著。     

车载装备噪声控制探讨

车载装备(如柴油发电车)的低噪声设计主要是针对装备工作时的噪声组成、特点,结合噪声的控制方式和阻性、抗性消声原理把噪声控制在声场内,限制其传播,采取减震、隔声和消声等措施,使其强度和能量衰减,从而达到低噪声工作的目的.     

BC131变速器阻尼降噪结构设计

本文说明了对BC131汽车变速器取力孔盖板做阻尼处理后,可降低噪声声功率级3.2dB,本文分三部分:(1) 阻尼结构的减振降噪机理;(2) 实验装置;(3) 声压级及声功率级的测量和计算。     

隧道沥青路面的降噪性能

针对隧道路面噪音大,对司乘人员造成困扰,采用驻波管法对混合料类型、路面厚度、材料空隙率等因素对路面降噪性能的影响进行研究,并通过试验路对研究结果加以验证.研究表明:1 000 Hz以下频率吸声效率可作为降噪性能的评价指标,对于大空隙型沥青混合料TSEM13,材料厚度在4 cm,空隙率20%时混合料的吸声能力最强,峰值吸...     

车内自适应有源消声系统次级声源布放试验

在构建车内双次级声源有源消声系统的基础上,对系统中次级声源的布放进行了试验研究,分析了双次级声源的布放、次级声源与误差传声器的相对位置对车内消声区域和消声效果的影响,确定了次级声源和误差传声器的合理布放方案。研究表明,当误差传声器与次级声源的数目相同、误差传声器位于次级扬声器的中心线上,且与次级声源相距200 mm左右时消声效果最好。讨论了不同车型车内次级声源和误差传声器布置的可行性,给出了客车、货车和轿车车内次级声源和误差传声器布放的合理方案,可为多次级声源车内有源消声系统的设计提供参考。     

Dynamic behaviour of a high-speed train hydraulic yaw damper

This paper focuses on revealing the dynamic behaviour of a hydraulic yaw damper under very small excitation conditions. First, the measured yaw damper movement is presented when a train experiences unstable motions. It shows that the yaw damper is characterized by very small harmonic movement between 0.5 and 2?mm. Following this, a simplified physical model of the yaw damper is developed which has the ability to reproduce its dynamic performance in the range of operating conditions, and then suitably validated with experimental results. At last, the dynamic behaviour of the yaw damper under very small amplitudes is investigated by comparing with its static behaviour, and the dynamic stiffness and damping in terms of key parameters are studied. It is concluded that there is a great difference in the damper performance between dynamic and static conditions which is caused by the internal damper flexibility under small amplitudes. The percentage of entrapped air in oil, rubber attachment stiffness, and leakage flow have a great effect on the dynamic behaviour of the yaw damper related to the dynamic stiffness and damping. The effect is even more remarkable for smaller amplitudes regarding the dissolved air in oil. Oil leakage has a greater impact on dynamic damping than dynamic stiffness. The series stiffness of the yaw damper is mainly provided by the spring effect of the oil when the rubber attachment stiffness reached a certain limit, and an additional increase in rubber attachment stiffness becomes useless to further enhance the overall stiffness of the damper.