基于润滑降噪实验的车床挂轮噪声分析

以一台C630车床空转噪声的测试数据为依据,分析了齿面摩擦对车床挂轮噪声的影响,以及摩擦激励频率与齿轮啮合频率的关系,并通过涂油润滑降低挂轮噪声的实验对此进行了验证。结果证明:齿面摩擦对齿轮振动的激励频率是啮合频率的2倍,可以利用适当的润滑有效地抑制齿轮噪声的高频成分。     

降低制动摩擦振动的制动器结构拓扑优化设计

本文建立起某车型盘式制动系统三维有限元模型,分析了该制动系统的摩擦振动噪声特性,并基于ABAQUS/Optimization模块对该制动系统进行结构拓扑优化设计,在满足轻量化的目标要求下改善摩擦振动噪声问题.结果表明:制动系统在摩擦力作用下可能出现四种振动模态,且产生频率为3632.4 Hz的振动噪声的倾向和强度最大.产生该频率摩擦振动噪声的原因是由于制动钳的第4阶模态频率与制动盘的第11阶模态频率非常接近,在摩擦力作用下容易产生共振.通过对制动钳进行结构拓扑优化设计,移除制动钳两侧区域的材料,使其在满足重量最小的目标前提下将第4阶模态频率降低到2804 Hz,从而避免与制动盘发生共振,且制动钳的重量减轻了17.1％.进一步采用复特征值分析对结构优化后的制动系统进行摩擦振动噪声特性预测,结果表明制动系统仅有两组相邻模态出现模态耦合现象,且原始制动系统出现的3632.4 Hz的振动噪声频率已经消失,制动系统摩擦振动噪声问题得到显著改善.     

水润滑引起摩擦噪声的机制及实验研究

水润滑摩擦噪声是一种较为常见的现象,会影响产品性能和环境舒适性.分析水润滑引起的摩擦因数一速度特性与摩擦振动系统稳定性的关系,对橡胶块与玻璃片的水润滑摩擦噪声进行实验研究.结果表明:水润滑引起的摩擦特性对系统具有负阻尼作用,当系统等效阻尼为负时,系统失稳,形成摩擦自激振动,是产生水润滑摩擦噪声的根源;摩擦元件的固有频率决定摩擦噪声频率,不同的支撑方式会改变系统模态频率,从而影响摩擦噪声频率.     

摩擦噪声有限元预测

发展一种利用商业有限元软件进行摩擦系统全模型摩擦噪声预测的方法,可以对包括摩擦力和真实边界条件下的摩擦系统的复特征值进行分析,提出进行摩擦噪声预测的主要步骤.该方法能够大大提高摩擦噪声预测分析的精度和效率.利用该方法分析往复滑动摩擦系统的噪声发生趋势,获得系统特征方程的特征根及其变化特性,据此可判断摩擦系统自然频率和可能发生摩擦噪声的频率.计算结果表明,摩擦因数和滑动方向对系统摩擦噪声的形成有重要影响,摩擦噪声发生时摩擦系统具有振动模态重合的特点.将计算得到的系统可能发生摩擦噪声的频率与系统的试验噪声频率进行比较,发现有比较好的一致性.     

摩擦片-卡簧系统摩擦噪声测试与仿真分析

为了研究摩擦片-卡簧系统摩擦产生的振动噪声机理,文中建立了摩擦片-卡簧-卡钳系统的三维几何模型,运用有限元方法对卡簧进行了模态分析,得到了卡簧的主要模态振型和固有频率。进一步搭建摩擦片-卡簧-卡钳系统振动噪声测试试验台,对摩擦片两端分别与卡簧摩擦引起的振动和噪声进行试验测试,获取了卡簧主要的振动和噪声频率。通过对卡簧固有频率和振型、振动和噪声的频率及主要振动方向的对比分析发现,产生的振动和噪声频率分别为1 565,2 914,4 800 Hz,主要振动方向分别与卡簧第7,11及15阶模态频率和振型方向具有较好的一致性,摩擦产生的振动和噪声与卡簧固有特性相关。文中所做研究为进一步优化刹车片-卡簧结构参数,抑制卡簧摩擦噪声提供了参考。     

基于小波变换的摩擦噪声激励源的研究

在往复滑动试验机上作了金属摩擦噪声试验,试验期间同时测量了摩擦噪声、摩擦振动三维加速度和名义摩擦力等动态信号,这些信号含有与摩擦振动激励源有关的信息。应用小波变换技术对这些信号进行了分解,在对应摩擦振动主频的小波分解细节分量中,可以清楚地看出激励摩擦振动的摩擦力动态分量,从而说明了摩擦噪声是由波动变化的摩擦力所引发。     

基于摩擦自激振动升频效应的超低频振动能量收集

低频振动在环境中广泛存在,针对目前低频振动能量收集效率低的问题,提出将外界低频振动转化成摩擦系统的自激振动,实现低频振动到高频振动的升频转换,以达到提高低频能量收集效率的目的 .为此,首先建立了集总参数模型,从理论上阐明低频振动能量收集方法的可行性,并分析模拟了该模型压电电压与功率的输出特性;其次分别设计了往复摩擦自激振动能量收集试验和压电悬臂梁碰撞能量收集试验,对比分析将低频振动转化为摩擦振动能否提高压电输出功率.试验与仿真结果表明,利用摩擦自激振动能够显著提升振动频率.摩擦自激振动电压幅值随着激励频率的增大而增大,与碰撞电压相比,其电压幅值较低,但是频率得到了大幅提升.由于频率的提升,压电振子的能量输出大幅提升,使得超低频振动能量收集性能明显提高.     

陶瓷髋关节假体系统摩擦噪声问题的有限元分析

建立陶瓷髋关节假体系统有限元模型,采用ABAQUS复特征值分析法对陶瓷髋关节假体系统可能出现的摩擦噪声问题进行分析,并探讨了系统参数和振动噪声之间的关系。研究结果表明,髋臼子系统和球头子系统均有可能是摩擦噪声的主要声源。摩擦因数增大导致髋关节系统发生模态耦合,从而增强系统的振动强度和噪声产生倾向。髋关节系统摩擦噪声主要出现在其绕X轴和Y轴转动,但是两种状态产生振动的振型模态有所区别。通过对速度和系统摩擦振动噪声的关系研究后发现,髋关节异响问题往往出现在速度较低的时候,当速度大于一定临界值时,系统保持稳定。此外,当载荷越大时,摩擦界面形成应力集中和能量堆积,导致系统产生更多频率的不稳定振动,且振动强度和倾向增大。合理地选择球头直径,对改善髋关节摩擦噪声有积极的效果。文中当球头直径为36 mm时髋关节系统处于稳定状态,没有摩擦振动噪声产生。另外,通过降低股骨柄弹性模量,使其等于股骨弹性模量后,能够显著改善系统振动噪声倾向,降低振动强度,这对改善摩擦噪声问题有积极作用。     

摩擦驱动型压电叠堆直线电机的工作机理

以一种典型的摩擦驱动型压电叠堆直线电机结构为例,对摩擦驱动型压电叠堆直线电机的振动摩擦驱动机理进行研究.结合电机系统的振动脱离模型,分析了电机定子与动子脱离的力学条件,进而分析电机结构参数和工作参数对椭圆运动和振动脱离性能的影响.对原理样机进行了试验研究,结果表明,压电叠堆的激励电压、激励频率和电机的预压力对电机的振动脱离性能有显著影响.     

蜗壳壁厚对离心风机振动噪声影响的数值研究

采用数值方法分析了蜗壳壁厚对离心风机在气动力激励下蜗壳受迫振动辐射噪声的影响.首先采用CFD方法模拟了风机内部的非定常流动,得到蜗壳壁面的非定常气动载荷分布;然后采用有限元方法计算蜗壳在非定常载荷作用下的受迫振动特性;最后采用边界元方法预测了蜗壳受迫振动激发的噪声声场及声功率.基于上述方法,比较分析了蜗壳壁厚对振动噪声辐射功率的影响.结果表明,并不是蜗壳的壁厚越大,其振动噪声越低,而是对应确定的激励频率,存在最佳的壁厚尺寸或各部分不同壁厚的尺寸组合.     

基于刚柔耦合的行星齿轮减速器减振降噪研究

针对某精密行星齿轮减速器的振动噪声问题,通过Romax Designer软件建立刚柔耦合动力学模型;并对减速器箱体进行模态分析,提取箱体的前六阶约束模态振型和固有频率,确定产生噪声的共振频率点;同时分析了齿轮传动误差、齿轮时变啮合刚度等激励的特性.提出通过齿轮修形降低减速器内部动态激励进而减小振动和噪声的方法,并使用L...     

基于温度效应的多自由度齿轮系统的非线性动力学分析

齿轮在工作时,由于功率损耗和环境温度等原因,引起齿轮轮体及箱体的温度发生变化,影响齿轮传动性能。以直齿圆柱齿轮传动系统为研究对象,考虑齿面摩擦、齿侧间隙和时变啮合刚度等非线性因素,引入温度变化的影响,建立六自由度的齿轮系统非线性动力学模型,并采用4~5阶龙格-库塔算法对模型进行求解,结合分岔图、相图和Poincare映射图,分析温度变化和激励频率对齿轮系统动力学的影响。结果表明,温度变化对系统的影响与激励频率取值有关;系统随着激励频率的变化会表现出不同的动态特性响应,包括单周期响应、多周期响应以及分岔和混沌响应。相关结论为进一步改善齿轮系统的设计和安装提供了参考。     

Dynamic behavior analysis of spur gears with constant & variable excitations considering sliding friction influence

A new analytical model of a spur gear system with sliding friction is presented. Unlike previous models, the excitation consists of two parts: the rotational driving speed of the pinion and the drag torque acting on the gear. The proposed model was validated with the finite element model. Using numerical method, the steady state resolutions was obtained to mainly demonstrate the nonlinear characteristics under both constant and variable excitations. The results obtained illustrate that sliding friction could introduce additional vibration. Moreover, the sliding friction even could decrease the dynamic transmission errors under proper operation condition. Further, the bifurcation diagram was plotted to show the influence of the rotational driving speed of the pinion on the dynamical characteristic of the gear system. Finally, the fluctuated excitation was used to exhibit their different effects on the gear system, which should form the basis of further analytical and experimental work in the gear dynamic area.     

Quasi-Static and Dynamic Behaviors of Helical Gear System with Manufacturing Errors

Time?varying mesh stiffness(TVMS) and gear errors include short?term and long?term components are the two main internal dynamic excitations for gear transmission. The coupling relationship between the two factors is usually neglected in the traditional quasi-static and dynamic behaviors analysis of gear system. This paper investigates the influence of short?term and long?term components of manufacturing errors on quasi?static and dynamic behaviors of helical gear system considering the coupling relationship between TVMS and gear errors. The TVMS, loaded static transmission error(LSTE) and loaded composite mesh error(LCMS) are determined using an improved loaded tooth contact analysis(LTCA) model. Considering the structure of shaft, as well as the direction of power flow and bearing location, a precise generalized finite element dynamic model of helical gear system is developed, and the dynamic responses of the system are obtained by numerical integration method. The results suggest that lighter loading conditions result in smaller mesh stiffness and stronger vibration, and the corresponding resonance speeds of the system become lower. Long?term components of manufacturing errors lead to the appearance of sideband frequency components in frequency spectrum of dynamic responses. The sideband frequency components are predominant under light loading conditions. With the increase of output torque, the mesh frequency and its harmonics components tend to be enhanced relative to sideband frequency components. This study can provide effective reference for low noise design of gear transmission.     

风力发电机组齿轮系统内部动态激励和响应分析

齿轮的啮合动态激励是齿轮系统产生振动和噪声的基本原因,齿轮系统在内部动态激励下的响应分析,对齿轮系统的设计和使用具有重要的意义。建立了考虑齿轮箱内部激励时的有限元动力分析微分方程,通过计算1.5MW风力发电机增速箱在刚度激励和误差激励作用下的动态响应,进而得出增速箱的振动烈度。     

沟槽织构化表面影响摩擦振动噪声机理

在列车制动盘蠕墨铸铁材料表面上制备出平行间隔分布的沟槽表面织构,将其和光滑表面进行摩擦噪声对比试验,并利用有限元软件ABAQUS/Explicit(显式动态求解器)对试验进行数值模拟分析,研究沟槽织构化表面影响摩擦振动噪声的机理。结果表明,本试验条件下的光滑表面会产生较高强度的噪声而沟槽表面几乎不产生噪声,利用有限元软件ABAQUS/Explicit可以很好地模拟试验现象并揭示沟槽表面织构影响界面摩擦振动噪声的机理,即沟槽织构表面在对磨球滑过并碰击沟槽时引起的摩擦力波动能有效的打断摩擦界面的连续接触,作为不连续激励扰乱系统的自激振动,抑制界面摩擦力和振动加速度高频成分的形成并最终降低摩擦噪声。     

Dynamic characteristics analysis and experimental research on a new type planetary gear apparatus with small tooth number difference

Aimed at an internal mesh planetary gear with small tooth number difference (PGSTD) reducer, this paper proposes dynamic characteristics analysis. First, static finite element (FE) analysis is performed to check the structural strength with the stress distribution in the gear teeth. Second, by means of the dynamic contact FE method, the internal dynamic excitations of teeth mesh are obtained, including mesh stiffness excitation, transmission error excitation and mesh impact excitation. According to the established model for dynamic FE modal analysis, the natural frequencies and mode shapes of the planetary gear apparatus (PGA) are calculated, and its structural dynamic response and acceleration noise are researched with the comprehensive consideration of internal and external excitations. Finally, the noise and vibration testing on the PGA is carried out by utilizing the vibration test equipment. The results confirm that the predicted values are consistent with the experimental results.     

Experimental study on vibration characteristics of double-helical gearbox with isolators

A power closed double-helical gear test rig with isolators was created to investigate the dynamic response characteristics of the double-helical gearbox. Experimentally, the vibration accelerations of the bearing seat, machine foot, and base were tested under various working conditions. Experiments validated the validity of the generalized finite element theory-based dynamic model of the double-helical gear system. The study found that the unloaded vibration of the gearbox is greatly caused by the shaft frequency excitation due to assembly/manufacturing errors. As the load increases, the assembly/manufacturing errors are compensated by the system deformation. In the acceleration spectrum of the bearing seat, it is found that the tooth surface modification can reduce the amplitude of the mesh frequency, but the bearing outer ring frequency components are increased. That is, the axial movement of double-helical gears is intensified. Furthermore, the closer the excitation frequency is to the natural frequency of the base, the worse the vibration isolation effect is.

     

发电机组橡胶柱销联轴器异常振动噪声诊断

为诊断某型柴油发电机组产生的异常噪声故障,将经验模态分解方法(empirical mode decomposition,简称EMD)和Hilbert变换用于发电机主轴承的非平稳振动信号处理,有效提取了主轴承振动信号的时频特征,对机组振动噪声信号、发电机主轴承振动和轴系扭振信号进行了分析。诊断结果表明,由于柴油机激励下机组轴系扭振幅值过大,引起柱销联轴器橡胶件表面的相对运动,产生干摩擦作用力,导致机组轴系产生间歇性的异常振动噪声。该方法对旋转轴系部件摩擦引起的振动噪声故障诊断具有参考价值。