共查询到20条相似文献,搜索用时 109 毫秒
1.
2.
3.
4.
高速动车组运行速度越高,车内低频段噪声就越显著,乘坐的舒适性也会越差。为了提高高速动车组乘坐的舒适性,降低噪音对乘客的影响,高速动车组在设计过程中采用各种降噪技术来满足相关标准的要求,满足乘客对舒适坐乘环境的要求。 相似文献
5.
6.
采用阻尼技术,以车轮表面贴阻尼板的方式设计降噪车轮.利用有限元分析方法,对贴有降噪阻尼板的降噪车轮和无处理车轮进行模态计算、谐响应计算,并进行相应的试验测试.模态计算结果显示,在高频段阻尼车轮减振降噪效果明显优于无处理车轮.谐响应计算表明,在相同激励力作用下,与无处理车轮相比,阻尼降噪车轮在较大频率范围内同一节点的动力响应有很大程度的降低.试验测试证明在车辆速度较低时,两者产生的噪声水平相当;但是,在车辆速度较高时,阻尼降噪车轮具有明显的降噪效果.因此采用在结构表面上敷设一层约束层,约束层上粘贴薄层的黏弹性材料,然后在最上面增加一层约束层的方式设计车轮阻尼装置,能起到较好的减振降噪效果. 相似文献
7.
为解决铁路列车在轻量化、高速化的过程中带来的一系列车辆振动和噪声问题,针对已有车体结构,重点研究了地板减振器参数变化对改善车辆隔声性能的影响。首先,开展车内噪声特性及车内噪声源识别测试,探明车内噪声的显著频段、主要声源源强及分布特性;其次,对比分析地板内部安装减振器前后车辆噪声特性的变化,明确地板减振器的降噪效果;最后,运用基于声学实验室测试的方法对地板减振器各类参数开展研究和优化设计。研究表明:地板结构为车内噪声主要传声结构和声源分布区域;安装地板减振器可以有效提高地板结构的隔声量,从而达到抑制车内噪声的目的;改变地板减振器刚度、邵氏A硬度、阻尼、载重及数量均对地板结构隔声性能有一定影响。本研究可为轨道车辆减振降噪设计提供依据。 相似文献
8.
针对一款前置后驱车型传动系统存在的扭振问题,应用AMESim软件建立仿真分析模型,使用扭振测试结果验证了模型的有效性。基于仿真模型分析双质量飞轮的作用机理,开展双质量飞轮参数匹配设计。实车验证结果表明:所匹配的双质量飞轮具有较好的减振降噪效果,扭振幅值明显降低,消除了传动系统在工作转速范围内的共振,座椅导轨振动降幅达0.1g,车内噪声降幅达7dB(A)。主观评价该车乘坐舒适性有明显改善,与客观测试结果一致。 相似文献
9.
《机械制造与自动化》2016,(3)
设备的振动噪声是衡量其舒适性和性能的重要指标之一。为此针对某型号流体机械进行隔振设计,并开发相应设计软件。利用软件研究上层刚度、下层刚度、阻尼和中间质量对系统隔振效果的影响规律。结果表明,刚度的增加,系统的隔振效果变差;阻尼在共振区域有利于减振,但随着频率的增加,阻尼会降低隔振效果,如果通过改变阻尼的方式提高隔振效果,应选择改变上层阻尼。 相似文献
10.
车身壁板的振动和噪声影响车辆NVH性能,在车身壁板粘贴阻尼衬层能够起到减振降噪的作用。利用强迫共振法测试基板(钢板)、自由阻尼结构(钢板+纯橡胶)、约束阻尼结构(钢板+纯橡胶+约束层)以及多层阻尼结构(钢板+纯橡胶+约束层+纯橡胶)四种阻尼结构试样。分析试样频谱图共振曲线得到如下结论:钢板附上衬层后的共振频率均要比原钢板试样的共振频率小;自由阻尼结构、约束阻尼结构、多层阻尼结构相对于基板的减振百分比分别为64.19%、71.77%、73.66%,减振效果依次增强;钢板、自由阻尼结构、约束阻尼结构、多层阻尼结构的阻尼因子分别为0.008、0.019、0.030、0.032,阻尼因子越大,阻尼性能越好,减振性能越强。并且从微观力学角度,对自由阻尼结构、约束阻尼结构、多层阻尼结构的减振机理进行了分析。 相似文献
11.
All precision machine tools and measuring machines rely on the stiffness, long term stability and damping properties of a structural material for their static and dynamic performance and, of course, the manufacturing cost of the machine depends on the structural materials chosen. This article outlines the main properties and relative merits of the more common structural materials and describes in more detail epoxy granite, a new material which has been blended to overcome the inherent disadvantages of more traditional materials. 相似文献
12.
Modelling viscoelastic materials is always difficult since such materials store energy as well as dissipate it to the thermal domain. Whereas modelling the elastic behaviour is easy, modelling the energy dissipation mechanism poses difficulty. This paper presents a theoretical study of the dynamics of a viscoelastic rotor-shaft system, where the internal material damping in the rotor-shaft introduces a rotary force well known to cause instability of the rotor-shaft system. An efficient modelling technique that assumes coupled (thermo-mechanical) augmenting thermodynamic field (ATF) to derive the constitutive relationships is found more suitable in comparison with the viscous and hysteric damping models, and is used to model the viscoelastic rotor material. Dynamic behaviour of an aluminium rotor is predicted through viscoelastic modelling of the continuum to take into account the effect of internal material damping. Stability limit speed (SLS) and unbalance response (UBR) amplitude are used as two indices to study the dynamics. It is observed that, the ATF approach predicts more reliable SLS and UBR amplitude in comparison with the viscous and hysteretic model of rotor-internal damping. Composite rotor-shaft assumed by reinforcing the aluminium matrix with carbon fibre is found to postpone the critical speeds and thus make available, higher speed of rotor operation and lower UBR amplitude in comparison with pure aluminium rotor-shaft. Finite element method is used for modelling and analysis. 相似文献
13.
针对汽车车身减振降噪需求,开发新型复合黏弹性阻尼材料。基于经典的自由阻尼和约束阻尼耗能原理,提出了一种含弹性约束的具有剪切和弯曲复合耗能机制的复合阻尼层结构。基于层间位移连续关系和薄板理论建立了阻尼复合板的位移方程和应变能能量方程,针对局部阻尼敷设及四边简支边界条件,结合假设模态法,推导出了复合阻尼板的运动微分方程、振动频率特征值方程等,求解得到了复合阻尼板的固有频率及损耗因子。复合阻尼层可用于研究单相材料不同参数特性及多相材料性能对比,且随着弹性层的上移,减振性能越好。复合耗能机理公式的推导,也为其在汽车上应用提供理论依据。 相似文献
14.
为减小薄壁加筋结构在动态环境下的振动,提出了加筋肋布局和阻尼层拓扑一体化设计方法。以含表层阻尼材料的薄壁加筋板结构为研究对象,结合阻尼材料惩罚模型与基结构优化方法,引入筋条密度和阻尼单元密度两类独立设计变量,考虑筋条和阻尼材料的体积约束,建立最小化动态柔度的阻尼材料拓扑和筋条布局的协同优化模型,实现面向动态响应最小化的含阻尼层的薄壁加筋结构最优设计。通过不同阻尼、不同频率下的含表面阻尼层加筋板的多个数值算例,验证了所提方法和模型的有效性。 相似文献
15.
为了实现对磁致伸缩和压电材料迟滞特性的描述,建立高精度前馈补偿系统,对Preisach模型一阶回转曲线的预测方法进行了研究。首先,介绍了一阶回转曲线及经典插法预测一阶回转曲线的基本原理,着重指出线性经典插值法对Preisach模型一阶回转曲线的预测存在不足;其次,在此基础上,利用非线性变换的思想,提出了辅助线法预测一阶回转曲线;最后,实验比较了超磁致伸缩材料(giant magnetostrictive material,简称GMM)与压电陶瓷(piezoelectric ceramic transducer,简称PZT)两种迟滞情况下,辅助线法和经典插值法对迟滞一阶回转曲线的预测结果。实验结果表明:在GMM迟滞下,对任意一阶回转曲线的预测数据,辅助线法的均方根误差(root mean square error,简称RMSE)最大减少为经典插值法的14.22%;对所有预测数据,辅助线法的RMSE减少为经典插值法的29.42%;在PZT迟滞下,对任意一阶回转曲线的预测数据,辅助线法的RMSE最大减少为经典插值法的18.18%;对所有预测数据,辅助线法的RMSE减少为经典插值法的41.07%。辅助线法对一阶回转曲线的预测精度整体高于经典插值法,且迟滞效应的非线性误差越高,预测精度较经典插值法越优异。 相似文献
16.
《Measurement》2016
Damping performance of lightweight composite structures, like fibre reinforced plastics (FRPs) is more efficient than the conventional materials. This phenomena was found valuable in the aerospace and transport industries. For this reason accurate material properties of FRPs are required for precise prediction of dynamic response. However, the given properties are often burden with a significant uncertainty level due to environment influence which includes air damping, temperature changes, humidity, etc. The present study concerns with the air damping influence on the dynamic behaviour of laminated composites plates with moderate damping level. The effect on dynamic characteristics is evaluated experimentally using a vacuum chamber and a laser vibrometer. Resonant frequencies and modal loss factors changes are investigated in terms of material type, sample size and excitation amplitude. A semi-automatic and time efficient two-step testing procedure is developed for a precise measurement of loss factors of laminated composite plates. 相似文献
17.
为实现阻尼结构减振优化,从阻尼材料的力学本构出发,基于虚功原理建立了约束阻尼板动力学平衡方程,从阻尼耗能角度推导出模态损耗因子解析计算式。构建了以模态损耗因子最大且模态频率变动最小为目标、以阻尼材料用量为约束的阻尼板多目标优化数学模型。在对模态损耗因子及模态频率灵敏度进行推导的基础上,构建了归一化复合灵敏度算式,并引入拓扑渐进法求解优化模型。编制出阻尼板渐近法优化程序,并对阻尼板进行了优化仿真。结果显示,采用多目标拓扑渐进优化,既能大幅提高阻尼材料的减振效能,又能保证阻尼板频率特性的稳定,且可较大幅度地降低阻尼材料用量。对阻尼板进行了谐响应分析,验证了优化结果的有效性。该优化法在对结构动力学特性有严格要求的减振设计中存在应用前景。 相似文献
18.
Michael I. Friswell Jayanta K. Dutt Arthur W. Lees 《International Journal of Mechanical Sciences》2010,52(10):1319-1324
Damping in the stator of a rotating machine is able to reduce the unbalance response, and increase the speed where the stability limit is reached. However, damping in the rotor is destablising and the analysis of rotors with internal viscous damping is well established. The drive towards composite and laminated rotors mean that the viscous damping model is not always appropriate, and viscoelastic material models whose properties depend on frequency should be used. These properties may be measured experimentally and the analysis of structures containing viscoelastic material materials may be performed in the time domain using the ADF, ATF or GHM methods. This paper extends this analysis to rotors containing viscoelastic materials using the ATF approach. Other internal variable formulations for viscoelastic material may be used following the approach adopted in this paper with only slight modifications. Viscous damping in the rotor produces a skew-symmetric component in the ‘stiffness’ matrix; for viscoelastic models the skew-symmetric term appears in the internal variable equations. This paper gives an example to demonstrate the calculation of the stability limit speed for a machine. 相似文献
19.
An improved approach is introduced in damping measurement with atomic force microscope (AFM) for the in situ measurement of the offset phase shift needed for determining the intrinsic mechanical damping in nanoscale materials. The offset phase shift is defined and measured at a point of zero contact force according to the deflection part of the AFM force plot. It is shown that such defined offset phase shift is independent of the type of sample material, varied from hard to relatively soft materials in this study. This improved approach allows the self-calibrated and quantitative damping measurement with AFM. The ability of dynamic mechanical analysis for the measurement of damping in isolated one-dimensional nanostructures, e.g. individual multiwalled carbon nanotubes, was demonstrated. 相似文献