基于ADAMS的高速机车双列圆锥滚子轴承典型故障仿真分析

为研究故障状态下双列圆锥滚子轴承的动力学行为,通过三维建模软件实现轴承几何外形,在考虑单侧内圈剥离故障的情况下将几何模型导入多体动力学仿真软件ADAMS中,充分考虑各部件间的接触、激励、约束和载荷等条件进行动力学仿真。仿真结果与理论值的对比验证了该模型的有效性,通过分析轴承的动力学行为得出:内圈故障侧滚子经过故障时转速急剧下降,产生打滑现象;故障侧保持架也受到滚子冲击的影响,稳定性大大降低。     

滚动轴承故障的显式动力学仿真与接触特性分析

故障的存在会恶化轴承内部接触状态,影响其动态特性。为了揭示存在故障时滚动轴承内部接触状态的变化规律,以滚子轴承NU306为研究对象,建立了故障轴承(含内圈故障、外圈故障和滚动体故障)的非线性接触多体动力学有限元模型,采用显式动力学算法对轴承运行过程进行仿真,获得了滚动体与套圈及保持架接触力的变化曲线,揭示了故障对轴承内部接触状态的影响规律。研究结果表明:轴承故障会导致滚动体与套圈的接触力出现波动,内圈故障时波动频率最高,滚动体故障时波动频率最低,且套圈故障时接触力大于正常轴承;外圈故障导致滚动体与保持架接触力的幅值变化最大,而滚动体故障导致的波动频率最高。仿真结果与实验结果吻合良好,验证了有限元模型的有效性。     

YRT120型轴承滚道剥落故障仿真与研究

为了研究处于复杂工况下数控转台承载轴承滚道剥落的故障机理,需要对轴承外圈上滚道剥落故障下的动力学特性进行分析。以TK13250E数控转台承载部件YRT120型轴承为研究对象,利用ADAMS软件对YRT120型轴承外圈上滚道进行仿真分析,并通过理论计算和试验验证模型的准确性,解决了YRT120型轴承故障信号不易提取的问题。通过对YRT120型轴承外圈上滚道缺陷尺寸变化模型进行仿真,得到振动信号剧烈程度与缺陷参数之间的关系。结果表明,缺陷尺寸增大会导致更剧烈的振动,振动信号强烈程度对缺陷宽度变化更敏感。     

含外圈故障的高速列车轴承转子系统非线性动力学行为分析

针对高速动车组列车的轴箱轴承,建立一种含外圈故障的滚动轴承非线性动力学模型,并分析轴承在正常状态和故障状态下模型的非线性动力学行为。该轴承为高速列车圆锥滚子轴承,模型考虑了轴承间隙、滚子和滚道之间的非线性赫兹接触力、由于转子质量偏心引起的不平衡力等因素。对模型进行数值求解,通过对比仿真和实际求得的变刚度频率外圈故障特征频率验证了模型的正确性。得到系统复杂的非线性动力学响应,分析转子速度、故障尺寸等因素对系统稳定性的影响,随着转子速度和故障尺寸的增大,系统会逐渐偏离稳定的运动状态,更早地进入混沌。通过频谱图、相平面图、分岔图以及Poincare映射图进行系统分岔和混沌特性分析,发现了通往混沌的拟周期运动、阵发性和倍周期分岔途径。分析结果对研究列车轴箱轴承故障的产生机理和演化规律具有一定的价值。     

风力发电机组发电机前轴承故障预警及辨识* .txt

摘要：为实现风电机组发电机前轴承故障预警及辨识,将监控和数据采集系统(SCADA)时间序列数据和状态监测系统振动数据相结合,提出了一种时频域建模方法。首先,利用SCADA数据建立基于门控循环单元神经网络的发电机前轴承温度模型,并计算其温度残差特征;其次,提取发电机前轴承振动信号时域特征和频域特征;最后,将温度残差特征和振动信号时频域特征相融合,建立基于极限梯度提升的前轴承故障辨识模型,从而辨识发电机前轴承正常、内圈损伤、外圈损伤、轴不平衡、滚动体损伤5类情况。实验研究表明,该方法比单独利用振动信号特征开展前轴承故障预警辨识的准确率高,其正常、内圈损伤、外圈损伤的平均辨识准确率从87%、585%、65%,分别提升到885%、675%和74%。 .txt     

基于广义S变换与双向2DPCA的轴承故障诊断

将轴承故障诊断问题转化为故障信号时频图像的识别问题,提出一种采用双向二维主成分分析(two-directional,two-dimensional,principal component analysis,简称TD-2DPCA)的时频图像矩阵特征提取方法。首先,利用广义S变换将轴承故障信号变换为时频域图像,采用一种双向压缩的二维PCA方法对图像信息进行特征提取;然后,进行了轴承故障试验,分别采集了轴承在正常、内圈故障及外圈故障状态下的振动信号,采用所述方法对轴承3种状态下的时频分布图像进行特征提取,并根据集成矩阵距离(assembled matrix distance,简称AMD)实现图像的分类识别。试验结果表明,结合广义S变换的双向2DPCA特征提取算法可有效提高计算效率,同时具有良好的诊断性能。     

振动机械滚动轴承单点点蚀故障动力学研究北大核心

针对振动机械滚动轴承内、外圈单点点蚀故障,通过分析轴承工作状况及钢球通过缺陷时接触变形量和弹性接触力的变化,建立了振动机械轴承内、外圈单点点蚀故障的动力学模型,并通过数值仿真得到了振动机械轴承内、外圈单点点蚀故障频谱。以振动筛为载体进行试验研究,验证了理论模型的正确性及有效性。理论分析与试验结果一致表明:振动机械轴承外圈单点点蚀故障时的故障包络谱中有较为明显的调制现象,内圈单点点蚀故障时的包络谱有轻微的调制现象,与旋转机械轴承内外圈单点点蚀故障谱有明显的区别。     

轴承实测波纹度的动力学建模与振动特性分析方法

针对基于实测波纹度来预测轴承振动特性的研究方法较少的问题,提出了一种基于插值重采样的轴承实测波纹度动力学建模方法。以NU307E型圆柱滚子轴承为例,建立轴承波纹度的动力学模型,通过对轴承外圈、内圈和滚子的实测波纹度数据进行插值重采样,获得波纹度离散序列,并将其耦合到振动模型,建立轴承实测波纹度动力学模型进行仿真分析。最后进行了试验,验证了建模方法的正确性。     

风力发电机组发电机前轴承故障预警及辨识

为实现风电机组发电机前轴承故障预警及辨识,将监控和数据采集系统(SCADA)时间序列数据和状态监测系统振动数据相结合,提出了一种时频域建模方法。首先,利用SCADA数据建立基于门控循环单元神经网络的发电机前轴承温度模型,并计算其温度残差特征;其次,提取发电机前轴承振动信号时域特征和频域特征;最后,将温度残差特征和振动信号时频域特征相融合,建立基于极限梯度提升的前轴承故障辨识模型,从而辨识发电机前轴承正常、内圈损伤、外圈损伤、轴不平衡、滚动体损伤5类情况。实验研究表明,该方法比单独利用振动信号特征开展前轴承故障预警辨识的准确率高,其正常、内圈损伤、外圈损伤的平均辨识准确率从87%、58.5%、65%,分别提升到88.5%、67.5%和74%。     

振动机械滚动轴承单点点蚀故障动力学研究

针对振动机械滚动轴承内、外圈单点点蚀故障,通过分析轴承工作状况及钢球通过缺陷时接触变形量和弹性接触力的变化,建立了振动机械轴承内、外圈单点点蚀故障的动力学模型,并通过数值仿真得到了振动机械轴承内、外圈单点点蚀故障频谱。以振动筛为载体进行试验研究,验证了理论模型的正确性及有效性。理论分析与试验结果一致表明:振动机械轴承外圈单点点蚀故障时的故障包络谱中有较为明显的调制现象,内圈单点点蚀故障时的包络谱有轻微的调制现象,与旋转机械轴承内外圈单点点蚀故障谱有明显的区别。     

基于小波包近似熵和SVM的圆柱滚子轴承诊断

为了解决特种车辆变速箱圆柱滚子轴承由于振动信号的非线性、非平稳特征较为微弱,提取的特征量数值不明显且现实中难以获得大量含丰富特征的典型故障样本而难以对其进行准确诊断的问题,应用小波包近似熵和支持向量机对特种车辆变速箱圆柱滚子轴承进行诊断。首先,在自行搭建的模拟实验台上采集某型特种车辆变速箱圆柱滚子轴承正常、外圈磨损、滚动体故障、点蚀和压痕4种典型状态的振动信号;然后,分别提取4种典型状态振动信号的小波包近似熵值作为支持向量机的输入,根据支持向量机的输出结果来确定圆柱滚子轴承是否发生故障和故障类型。结果表明,该方法能有效对某型特种车辆变速箱圆柱滚子轴承的典型状态进行诊断,为其他相似变速箱圆柱滚子轴承的故障诊断提供一种参考途径,具有一定的工程实用价值。     

A fault diagnosis approach for roller bearing based on VPMCD under variable speed condition

Essentially the fault diagnosis of roller bearing is a process of pattern recognition. However, existing pattern recognition method failed to capitalize on the nature of multivariate associations between the extracted fault features. Targeting such limitation, a new pattern recognition method – variable predictive model based class discriminate (VPMCD) is introduced into roller bearing fault identification. The VPMCD consider that all or part of the feature values will exhibit interactions in nature and these associations will have different performances between different classes, which is always true in practice when faults occur in roller bearings. Target to the characteristics of non-stationary and amplitude-modulated and frequency-modulated (AM–FM) of vibration signal picked up under variable speed condition, a fault diagnosis method based upon the VPMCD, order tracking technique and local mean decomposition (LMD) is put forward and applied to the roller bearing fault identification. Firstly, LMD and order tracking analysis method are combined to extract the fault features of roller bearing vibration signals under variable speed condition; Secondly, the feature values are regard as the input of VPMCD classifier; finally, the working condition and fault patterns of the roller bearings are identified automatically by the output of VPMCD classifier. The analysis results from experimental signals with normal and defective roller bearings indicate that the proposed fault diagnosis approach can distinguish the roller bearing status-with or without fault and fault patterns under variable speed condition accurately and effectively.     

航空发动机主轴轴承失效模式分析

航空发动机圆柱滚子主轴承常常因为工作条件恶劣,发生失效。采用光学显微镜、扫描电镜、能谱仪、X射线光电子能谱等对服役后的圆柱滚子轴承进行失效分析。结果表明:根据失效机制与微观形貌对失效模式,可以将圆柱滚子轴承的失效模式分为8种不同的失效模式,包括划伤和擦伤、打滑蹭伤、压坑凹坑、疲劳剥落、振纹、受热变色、内圈烧伤、保持架镀银层磨损。对打滑蹭伤、烧伤和保持架镀银层磨损等失效模式的轴承进行分析,结果表明:在打滑蹭伤的轴承表面发现O元素,表明打滑蹭伤过程中发生了氧化磨损;在烧伤轴承表面发现了Fe的氧化物FeO和Fe₂O₃,表明轴承在烧伤时温度较高,润滑油膜被破坏,滚子和内圈互相接触发生剧烈磨损;保持架表面银层脱落,部分磨损区域露出铜表面,表明保持架在服役过程中发生了摩擦磨损。     

A Noise Analysis of Cylindrical Roller Bearings Operating Under Zero External Load

The purpose of this article is to numerically investigate one source of acoustic noise in roller bearings, that which results from the motion of the rollers in the bearing under zero external load. For the sake of simplification, it was assumed that the cylindrical roller bearings are infinitely long. Furthermore, the effects of the following on the noise of the bearing were also examined: the radial clearance of the bearing, the viscosity of the lubricant, and the number of rollers. The results of the study show that the fundamental frequency of the noise components of the cylindrical roller bearing corresponds to the multiplication of the number of rollers and the whirling frequency of the roller center. The acoustical frequency spectra of the cylindrical roller bearing are pure tone spectra, containing the fundamental frequency of the roller bearing and its superharmonics. The factors that decrease the sound pressure level of a cylindrical roller bearing include low lubricant viscosity, high radial clearance, and a reduced number of rollers. The results and discussions of the present article could aid in the design of low-noise cylindrical roller bearings.     

A Fatigue Life Comparison of Two-Row Tapered Roller Bearings and Spherical Roller Bearings

Tests were run to compare the fatigue life of two-row tapered roller bearings to that of spherical roller bearings. Both bearing types had an outer diameter of 110 mm with the spherical roller bearing having a 22 percent larger dynamic radial load rating than the tapered roller bearings. All tests were run at 165 percent of the respective two-row dynamic radial load ratings. The results show that both the indirect mounting (double cup or outer ring) and the direct mounting (double cone or inner ring) tapered roller bearings gave significantly better fatigue lives than the spherical roller bearings. These results appear to contradict the present ISO 281 standard which assigns a 1.15 b_m rating factor to spherical roller bearings compared to a b_m rating factor of 1.10 for that of tapered roller bearings.     

A blind deconvolution separation of multiple sources, with application to bearing diagnostics

A method is presented, geared to separating signals from different sources which are convoluted and mixed by the mechanical systems before being measured. The method is based on an automatically operating blind deconvolution separation method, with Kurtosis of the separated signals as the measure to be maximised. The application described involves bearings diagnostics, whereas with many classical diagnostic methods, Kurtosis is traditionally one of the accepted criteria for fault detection. The method is tested on simulation and experimental cases. Results show that separation is possible even when measurements are distanced from the vibration exciting sources of the faulty bearing. Furthermore, the method eliminates the effect of structural resonances, which often causes severe problems in classical diagnostic methods.     

New Stress-Based Fatigue Life Models for Ball and Roller Bearings

New stress-based life models are introduced to define “dynamic stress capacity” in rolling bearings for the first time. The generalized stress capacity equations are formulated, for both point and line contacts, in terms of distinct geometrical and materials parameters while the empirical constants are now material independent. Life equations are first developed for individual rolling element to race contacts and then statistically combined to estimate lives of both races, rolling elements, and, finally, the whole bearings for both ball and roller bearings. An estimate of the empirical constant for the ball bearing equation is derived by regression analysis of available experimental data. The applicable constant for roller bearings is then derived by relating the ball and roller bearing constants to the fundamental subsurface fatigue hypothesis applicable to both point and line contacts. For AISI 52100 bearing steel at room temperature, life predictions with the new stress-based equations are in complete agreement with those currently provided by widely used load-based formulations, where the empirical constant contains the elastic properties of AISI 52100 bearing steel. In addition to these life equations based on the magnitude and depth of maximum orthogonal subsurface shear stress and the volume of material stressed, a new model that eliminates life dependence on the depth of maximum orthogonal shear stress and relates life to only the subsurface maximum shear stress and the stressed volume is presented. Though the predicted life estimates with the currently used and newly introduced life models are comparable in the contact stress range of 2 to 3 GPa, the new model provides significantly higher lives at low contact stresses.     

考虑滚子位置变化的圆柱滚子轴承非线性刚度特性分析

以圆柱滚子轴承为研究对象,考虑轴承运转过程中滚子周向位置分布的周期性变化,对经典圆柱滚子轴承载荷分布理论进行改进,并对由此引起的轴承刚度时变特性进行分析,同时研究圆柱滚子轴承平均刚度及平均接触滚子数随径向力的非线性变化规律。为了对改进理论算法进行验证,采用有限元接触分析方法对圆柱滚子轴承刚度及滚子接触状态进行分析。研究结果表明,改进理论算法和有限元接触法均能准确预测轴承瞬时刚度的时变特性及平均刚度随径向力的非线性变化特性,同时证明轴承平均接触滚子数的改变是轴承刚度变化的根源。基于改进理论算法进而分析轴承初始径向游隙、径向力、滚子设计数量等关键参数对圆柱滚子轴承性能的定量影响规律。     

三排柱式回转支承非理想Hertz接触特性分析

传统方法对三排柱式回转支承的滚柱与滚道间的接触分析都是基于Hertz接触理论,然而滚柱与滚道的实际接触超出了Hertz接触理论的范围。针对该问题,重点研究了滚柱与滚道的非理想Hertz接触特性,得出了接触变形及接触应力沿滚柱轴向的变化规律。结合McEwen关于圆柱体法向接触理论,推导了滚柱与滚道接触区内部的应力场各应力分量解析表达式,并讨论了滚道失效与应力之间的关联。最后,建立了滚柱与滚道接触的3D有限元模型,仿真结果表明,接触区的应力分布与解析解基本吻合,结论可为三排柱式回转支承的设计与制造提供参考。     

Filtration and coating effects on self-generated particle wear in boundary lubricated roller bearings

A specially designed test system involving boundary lubricated roller bearings was used to study wear at low particle concentration levels. A separate oil system circulated the oil through the test bearings. The effects of self-generated contaminants from the system were studied. Even at very low concentration levels, self-generated contaminants can cause significant wear. The concentration of self-generated particles was very high during the running-in period. It is therefore important that the filtration be very efficient during this period. The experimental results show that filtration during run-in for 1 h with a 3 μm filter can reduce both the mass loss and the number of self-generated particles by a factor of 10. Furthermore, the results also show that while the bearings with standard rollers can have significant wear, those with coated rollers are at the same time almost unaffected by wear. Also, the number of particles generated in the contact was significantly less when using coated rollers. There were twice as many self-generated particles when using a standard bearing as those compared with a coated bearing.