STUDY ON VIBRATION REDUCTION BEHAVIOR FOR THE HYDRAULIC ENGINE MOUNT

In this paper,the metal hydraulic engine mount (HEM) with the orifice is presented,the construction of HEM is consist of hydraulic cylinder and the spring on the bottom,its mechanical model is given and dynamics equations are set up with considering kinematics conditions and continuous of fluid,the dynamics behavior of HEM including dynamic stiffness of fluid and transferability of HEM are studied here.The example of hydraulic engine mount is calculated,it is shown that the vibration reduction performance of the hydraulic engine mount of this paper is better.The analysis method of vibration reduction behavior for HEM in this paper can be used in designing of the reduction vibration devices and the HEM in this paper can be used in the practical engineering for reduction vibration.

Dynamic Analysis and Decoupling Control of Octo-pneumatic Actuator Vibration Isolation Platform

Control of a six-DOF vibration isolation platform is generally difficult which is due to the strong coupling among its input and output channels. The dynamic behavior and decoupling approach of a six-DOF vibration isolation platform with eight pneumatic actuators are investigated. Owing to the symmetric configuration design of the platform, the coupling among different channels is greatly weakened. When the payload＇s principal axes of inertia parallel to the platform＇s axes of symmetry and the payload＇s center of mass is at the extension line of the platform＇s central axis, the motion can be decomposed into two independent single-input single-output channels and two independent two-input two-output subsystems. The second-order subsystems are decoupled further with the simultaneous matrix diagonalization. Thus a decoupling control strategy is developed. Effectiveness of the decoupling approach is verified through experiments of the platform, and the experimental results show that vibrations of the platform are attenuated obviously owing to the active control.

Research and application on three-dimensional seismic and vibration isolation for building

This paper presents the study of a three-dimensional(3D) isolation system.Firstly,the authors investigated the effects of an innovative 3D isolator,which was composed of a connecting plate,a rubber pad for vibration isolation in the vertical direction and a horizontal rubber bearing for seismic isolation in both horizontal directions.Secondly,the authors designed such a vibration isolation system and installed it underneath two specific residential buildings which were built directly over an existing subway communication hub platform in Beijing.These buildings required good performance vibration and seismic isolation system to reduce the impact from the running of nearby subway trains.Finally,in situ tests were conducted for both the isolated and the non-isolated buildings for the purpose of comparison.The test results showed that the maximum acceleration response level of the isolated superstructure is reduced by 10% as compared to that of the platform.The maximum attenuation of vibration reaches up to 25 dB.The 3D system explored in this paper is very effective in control and suppression of building vibration induced by earthquakes or running of trains.

Optimizing Parameters of Rail-induced Vibration Isolation Trench Using Simplified FEM Approach

A simplified approach is proposed to reduce computational cost in conventional parametric optimization of open or in-filled trenches isolating rail-induced structural vibrations. In particular, it stands on an FEM-based hybrid optimization scheme consisting of multiple two-dimensional models and one global three-dimensional model. First, representative planar FE （finite element） models orthogonal to the rail-direction are identified. For each section, the sensitivity of the trench＇s design parameters, such as geometry and backfill materials, to its vibration screening effect is respectively evaluated. Second, a full trench along the rail-direction is determined according to the two-dimensional optimization result. The global performance of the optimal trench is simulated in the three-dimensional model and finally becomes a reference for practical design. By optimizing the design parameters of a case study project, the proposed approach has shown the capability of solving complex engineering problems at a minimum computational cost, therefore is applicable in determining design parameters of rail-induced vibration isolation trenches.

Tri-directional shaking table tests of vibration sensitive equipment with static dynamics interchangeable-ball pendulum system

Recently, the high-tech industry has become a key industry for economic development in many countries. However, vibration sensitive equipment located in these industrial buildings is vulnerable during earthquakes, which may cause huge economic loss. In this study, an innovative isolator for safeguarding the vibration sensitive equipment, namely, the static dynamics interchangeable^all pendulum system （SDI-BPS） is proposed and investigated to examine its protective capability for the vibration sensitive equipment during earthquakes through a series of tri-directional shaking table tests. The experimental results illustrate that the SDI-BPS isolator can provide significant damping to rolling types of base isolation systems for reducing the bearing displacement and size, and avoid the stress concentration, which can cause damage or scratches on the rolling surface of the isolator, to prolong its life span of service. The SDI-BPS isolator also provides excellent capability in protecting the vibration sensitive equipment and exhibits a stable behavior under long terms of service loadings and earthquakes.

Dynamics of installation way for the actuator of a two-stage active vibration-isolator

We investigated the behaviors of an active control system of two-stage vibration isolation with the actuator installed in parallel with either the upper passive mount or the lower passive isolation mount. We revealed the relationships between the active control force of the actuator and the parameters of the passive isolators by studying the dynamics of two-stage active vibration isolation for the actuator at the foregoing two positions in turn. With the actuator installed beside the upper mount, a small active force can achieve a very good isolating effect when the frequency of the stimulating force is much larger than the natural frequency of the upper mount; a larger active force is required in the low-frequency domain; and the active force equals the stimulating force when the upper mount works within the resonance region, suggesting an approach to reducing wobble and ensuring desirable installation accuracy by increasing the upper-mount stiffness. In either the low or the high frequency region far away from the resonance region, the active force is smaller when the actuator is beside the lower mount than beside the upper mount.

准零刚度非线性低频隔振器理论研究及应用

隔振器在各行业中得到广泛应用,传统线性隔离器因其简单、低廉、高可靠性和鲁棒性被广泛应用于工业中,然而由于其仅能够在激励频率大于√2倍固有频率时才能有效抑制振动,故存在静态承载能力和低频隔振性能之间的固有矛盾。近几十年来发展起来的非线性准零刚度(QZS)隔振器可以在保证高承载能力的前提下降低动刚度,从而将隔振频带拓宽到低频区域。从QZS隔振器的构造方法、优化与改进设计和工程应用等方面综述QZS隔振的主要研究进展,总结现有研究的不足,展望未来发展方向,为相关领域的研究人员提供参考。

考虑机组弹性的双层隔振系统刚度匹配方法

为解决柴油发电机组对不同类型和功率发电机的连接套与隔振系统刚度匹配问题,提出以广义弹性力做功为基础的能量解耦法来量化刚度匹配对双层隔振系统固有特性的影响.基于某内燃动力总成双层隔振系统建立3自由度和18自由度动力学模型进行分析.结果表明:3自由度模型能够反映系统耦合的主要特点,机组弹性模态频率与低阶刚体振动模态频率比大于2.96时可以降低刚体振动对弹性模态的影响;考虑惯性耦合和弹性耦合后,18自由度模型对应的频率比应大于4.10才可以显著降低该振动耦合.同一柴油机匹配不同惯性参数的发电机,均可参考小惯性参数发电机隔振设计时对应的频率比和刚度比进行双层隔振系统刚度匹配.

主动隔振系统负载特征参数动态辨识方法

针对主动隔振系统负载特征参数难以估计以及动态变化的问题,明确特征参数辨识对象并提出辨识方法,提升主动隔振系统的解耦控制效果。在三点支撑构型的减振系统基础上,建立主动隔振系统动力学模型和控制模型,推导动力学方程中的质量矩阵、刚度矩阵、阻尼矩阵以及解耦控制模型中的转换矩阵,提出主动隔振系统重心、质量、惯量负载特征参数的辨识方法,创建基于Simulink的主动隔振系统仿真模型并对实验平台进行搭建,通过仿真和实验使辨识方法的有效性得到验证。

某皮卡车动力总成悬置性能优化

动力总成悬置系统是影响车内振动响应的关键因素,是噪声、振动和声振粗糙度(NVH)性能优化中的重要一环。针对某皮卡车主观评价时方向盘怠速振动过大问题进行研究,通过测试发现,因动力总成悬置隔振能力不足,导致动力总成激励无法有效衰减,引发方向盘振动过大。针对该问题,对样车动力总成悬置系统进行开发,以解耦率为优化目标,基于非支配排序遗传算法(NSGA-II)和能量解耦法,使用iSIGHT与MATLAB进行联合分析,对发动机悬置隔振性能进行优化,结合实车进行优化验证,优化后悬置系统隔振量基本达到20dB,方向盘振动主观评价可接受,该研究方法对样车NVH开发有一定指导意义。

空调压缩机三点式橡胶隔振脚垫刚度优化与实验验证

针对某变频空调压缩机隔振系统性能不达标的问题进行优化设计,采用三点式隔振脚垫布置法搭建空调压缩机隔振系统模型,以橡胶隔振脚垫的刚度为关键优化参量,隔振系统固有频率及能量解耦率为优化目标,获取隔振脚垫刚度对隔振系统振动特性的影响规律及关键参量的最佳匹配方案,并通过隔振脚垫-压缩机系统振动特性测试验证方案的准确性。结果表明,优化后的压缩机橡胶隔振系统性能有较大提高,能够满足实际隔振需求。

基于NSGA-Ⅱ的纯电动汽车悬置系统隔振率优化

纯电动汽车的振动特性与传统内燃机汽车存在较大差异,本文针对纯电动汽车悬置隔振率不足的问题,提出了一种适用于悬置系统隔振率优化的研究方法。分析悬置系统各方向隔振率以及影响悬置隔振率的主要因素,确定了后悬置隔振率作为优化对象,提出通过优化悬置被动侧支架安装点动刚度来提升隔振率。采用第二代非劣排序遗传多目标寻优算法,以隔振率最优、质量比变化最小为寻优目标,对支架安装点动刚度目标值进行寻优,根据寻优结果对被动侧支架结构进行调整。试验结果表明,优化后的后悬置Y向隔振率从5.61提升至18.13 dB,驾驶员右耳旁噪声在24、48阶次下降9.76和5.03 dB(A),驾驶舒适性有明显改善。

集成调整功能的座椅非线性悬架设计

为提高工程车辆座椅的低频隔振能力,及适应驾驶员身高、体质量参数的差异性,设计了一种集成身高和体质量调节功能的座椅非线性悬架,建立了核心设计参数与其力-位移特性间的数学模型,确定了主要设计参数。基于ADAMS软件仿真验证了座椅悬架的力-位移特性、调整功能,并制造了物理样机进行了试验验证。结果表明,所设计的悬架具有较好的非线性特性,高度、体质量参数可调,且参数的调整不影响悬架的低频隔振能力。

散射型组合周期排桩带隙特性的影响因素研究

为明确散射型组合周期排桩带隙的影响因素及作用机制,在通过相似模型试验进行验证分析的基础上,对散射型组合周期排桩带隙产生机理进行分析,并采用有限元方法研究了不同影响因素下的带隙特征。结果表明:带隙范围内的竖向和横向加速度最大衰减程度分别达到95.9%和87.61%,带隙分布特征与数值模拟结果基本一致;散射型组合周期排桩带隙主要受填充率、周期常数、材料密度、基体弹性模量和晶格类型等因素影响;随着填充率减小和周期常数增大,散射型组合周期排桩更易于获得低频带隙,但带宽变窄;通过减小基体密度或增大散射体密度可获得较大带宽的高频带隙;随着基体弹性模量的增大,带隙的边界频率同步向高频迁移;对于圆形散射体,六角晶格构型的带隙性能整体优于正方晶格。研究结果可为散射型周期排桩优化设计及应用提供参考。

某300吨级矿用自卸车悬置系统分析和优化

针对某300吨级矿用自卸车存在振动和噪音过大的问题,通过原地实车测试,依据数据分析,找出了悬置系统隔振能力的薄弱点,为了进一步提高驾乘舒适性和减小振动带来的影响,从两个方面对现有悬置系统进行优化分析:一、对悬置支撑点位置进行优化;二、对减震器进行重新匹配选型。本论文综合运用声震测试、优化设计理论与技术,对该车动力总成悬置系统进行动态分析、优化设计与工程化改进,通过试验数据对比分析,提高悬置系统隔振性能。

汽车发动机悬置系统的隔振分析及优化设计

为提升汽车行驶过程中的舒适度,需保证汽车具有较好的隔振性能,因此,本文以汽车发动机悬置系统为例,研究汽车发动机悬置系统的隔振分析及优化设计。以该发动机悬置系统的实际参数为依据,进行汽车发动机悬置系统隔振性能解耦分析,并通过ADAMS软件,构建悬置系统仿真模型,获取悬置系统不同方向的解耦率结果,确定悬置系统隔振性能情况;并针对分析结果进行悬置系统设计优化。通过优化后的动刚度分析结果可知,优化设计后,发动机悬置系统的隔振性能满足标准需求。

基于NSGA-Ⅱ算法的动力总成悬置解耦与隔振最优匹配研究

发动机是车辆产生振动噪声的最主要激励源,动力总成悬置系统是隔振发动机振动噪声的主要部件,其隔振水平直接影响整车振动噪声表现。文章首先建立了MATLAB和ISIGHT联合仿真六自由度悬置模型,并利用NSGA-Ⅱ优化算法针对一款动力总成悬置系统进行了解耦与隔振最优匹配开发,试验验证结果表明,开发的悬置隔振水平表现优秀,隔振平均提升3.4 dB,较好的支撑了整车级噪声、振动和声振粗糙度(NVH)指标达成。

基于传递路径优化的某样车变速器啸叫改善

以某样车变速器3挡啸叫问题为研究对象,对“动力总成→悬置系统→车室内”的传递路径进行结构测试与分析。数据显示,该样车左悬置隔振量远远小于20dB要求,变速器齿轮啮合产生的振动通过此路径传递至车室内,最终被驾乘人员感知,引发抱怨。利用软件Test.lab,对整车状态下的悬置系统进行结构传递路径测试与分析,并通过软件MSC Adams建立动力总成系统模型,以悬置系统解耦率为优化目标进行优化设计,最终确认调整悬置刚度来优化问题。依据优化结果,快速制作悬置样件并装车验证,试验结果表明,样车更换新设计的悬置样件后,驾驶室内变速器3挡啸叫噪音降低明显,整车NVH性能得到提升。

混合动力总成悬置系统隔振性能分析与优化

针对实际运行中某混合动力客车存在的振动偏大问题,对原悬置系统进行振动加速度测试和隔振性能分析。基于隔振理论,以悬置隔振率和车内振动加速度为评价指标,以悬置软垫刚度和安装角度为变量,采用对称式和非对称式两种悬置系统布置方案对隔振性能最差的发动机端悬置进行优化设计,并采集两种悬置状态下的振动数据与原状态进行比较分析。结果表明,非对称式布置的悬置方案更适合于单侧受拉的混合动力总成悬置系统的布置。