Simulating the dynamic behavior of planetary gearbox based on improved Hanning function

Planetary gearboxes are widely used in industrial machines. They usually work in harsh environments giving rise to damages and high maintenance costs. Condition monitoring is a key action allowing one to detect the presence of such damage ensuring healthy running conditions. The knowledge of the dynamic behavior of such a gearbox can be achieved using modeling tools as a primary step before conditioning the monitoring subject. In addition, modeling a gear set can help in the stage of design in order to optimize physical and geometric parameters of the system. Therefore, in this work, a two-dimensional lumped parameter model is adopted to build all vibration sources. The time-varying mesh stiffness is approximated as a square wave form. A novel mathematical formulation is proposed to model the amplitude modulation phenomenon due to the rotational motion of the planets around the center of the gearbox. Finally, the overall vibration signal is concluded as a summation of all vibration components influenced by the modulation function.     

车辆手动变速箱油的摩擦学性能研究

根据手动变速箱油(MTF)的物理化学特性和手动变速箱的工作特点,研制了手动变速箱油,通过SRV-IV往复摩擦试验机比较了市售的国外品牌手动变速箱油的摩擦性能,并利用三维非接触表面轮廓仪观察了磨斑表面的磨痕变化.结果表明:研制的手动变速箱油在保持物理化学特性的基础上,在不同温度条件下,摩擦学性能优于进口手动变速箱油;同时发现MTF比GL-4更适合用于手动变速箱的润滑.     

基于Polytec激光测振仪和第二代小波的齿轮箱故障诊断

齿轮箱是机械设备中一种必不可少的通用零部件,也是故障多发部件,而齿轮失效又是诱发其故障的重要因素。因此发展新型齿轮箱故障诊断技术具有重要意义。搭建了基于Polytec激光测振仪的光学测量系统,拾取齿轮箱振动信号,采用第二代小波提取故障特征,达到了故障诊断的目的,可用于齿轮箱故障预知和智能维修。     

Effects of operating conditions on the Acoustic Emissions (AE) from planetary gearboxes

In the last decade, the use of acoustic emissions has received growing acceptance for its application in machine condition monitoring. This is because it offers good possibilities to diagnose failures at early stages and low rotational speeds. The use of acoustic emissions for condition monitoring of gears, however, is still an active field of research, because several questions remain unanswered. One of these questions is the effect of operating conditions on the AE generated during gear meshing. In this work, the results of experiments carried out on a non-faulty planetary gearbox test bench are presented. A planetary gearbox is considered, because of its usual application on machines subjected to variable operating conditions. The effects of lubricant temperature, load and rotational speed are investigated. The conclusions obtained from the experiments are used for the analysis of the AE measured on the planetary gearbox of a bucket wheel excavator.     

A comparative study of the effectiveness of vibration and acoustic emission in diagnosing a defective bearing in a planetry gearbox

Whilst vibration analysis of planetary gearbox faults is relatively well established, the application of Acoustic Emission (AE) to this field is still in its infancy. For planetary-type gearboxes it is more challenging to diagnose bearing faults due to the dynamically changing transmission paths which contribute to masking the vibration signature of interest.     

Multi-harmonic active structural acoustic control of a helicopter main transmission noise using the principal component analysis

This paper evaluates the feasibility and effectiveness, under controlled conditions, of active structural acoustic control of a helicopter main transmission in order to attenuate the vibration of the receiving roof panel and its sound radiation into the cabin. The vibroacoustic analysis of a typical helicopter drive train is conducted to extract the dominant tones generated by the various transmission stages. A finite element model of a Bell 407 transmission and simplified roof structure is developed in order to investigate various active control arrangements using piezoceramic actuators to control wave propagation in the gearbox supporting struts or receiving panel. The principal component analysis is used to extract the most significant control paths and reduce the control effort. A multiple frequency principal component least mean square (PC-LMS) algorithm is implemented on a laboratory setup and is used to successfully reduce up to seven gearbox tones simultaneously.     

Dimensionality reduction via variables selection – Linear and nonlinear approaches with application to vibration-based condition monitoring of planetary gearbox

Feature extraction and variable selection are two important issues in monitoring and diagnosing a planetary gearbox. The preparation of data sets for final classification and decision making is usually a multi-stage process. We consider data from two gearboxes, one in a healthy and the other in a faulty state. First, the gathered raw vibration data in time domain have been segmented and transformed to frequency domain using power spectral density. Next, 15 variables denoting amplitudes of calculated power spectra were extracted; these variables were further examined with respect to their diagnostic ability. We have applied here a novel hybrid approach: all subset search by using multivariate linear regression (MLR) and variables shrinkage by the least absolute selection and shrinkage operator (Lasso) performing a non-linear approach. Both methods gave consistent results and yielded subsets with healthy or faulty diagnostic properties.     

汽车变速箱Hy-Vo齿形链磨损特性的研究

针对汽车变速箱传动系统高转速、强磨损的特殊要求,通过内-外复合啮合Hy-Vo齿形链300 h的高速磨损台架试验,研究了汽车变速箱链条的摩擦磨损特性,对啮合传动过程中链条铰链副以及链板外廓与链轮的接触区进行了局部微观磨损形貌分析.结果表明:汽车变速箱Hy-Vo齿形链的综合磨损伸长由对滚异型销轴磨损以及链板外廓磨损组成,其中,对滚异型销轴的磨损机制为疲劳磨损.     

Subway Gearbox Fault Diagnosis Algorithm Based on Adaptive Spline Impact Suppression

In the signal processing of real subway vehicles, impacts between wheelsets and rail joint gaps have significant negative effects on the spectrum. This introduces great difficulties for the fault diagnosis of gearboxes. To solve this problem, this paper proposes an adaptive time-domain signal segmentation method that envelopes the original signal using a cubic spline interpolation. The peak values of the rail joint gap impacts are extracted to realize the adaptive segmentation of gearbox fault signals when the vehicle was moving at a uniform speed. A long-time and unsteady signal affected by wheel–rail impacts is segmented into multiple short-term, steady-state signals, which can suppress the high amplitude of the shock response signal. Finally, on this basis, multiple short-term sample signals are analyzed by time- and frequency-domain analyses and compared with the nonfaulty results. The results showed that the method can efficiently suppress the high-amplitude components of subway gearbox vibration signals and effectively extract the characteristics of weak faults due to uniform wear of the gearbox in the time and frequency domains. This provides reference value for the gearbox fault diagnosis in engineering practice.     

基于灰色预测的直升机齿轮箱状态预测方法

作为直升机上重要的关键部件,直升机齿轮箱能够将动力转换为动力输出形式,从而满足不同形式下动力的需要。针对直升机齿轮箱状态无法准确预测的技术难题,本文将灰色系统理论中的灰色预测方法运用到直升机齿轮箱中,有效解决了齿轮箱使用状态难以准确预测的技术难题。首先对采集到的直升机齿轮箱的不同的振动信号进行特征提取,然后采用信息融合技术,将不同振动信号的特征值进行融合,最后运用灰色预测方法对直升机齿轮箱的使用状态进行预测。文中对所提出的方法进行了试验验证,结果表明,所提出的基于灰色预测的直升机齿轮箱状态预测方法能够实现对直升机齿轮箱的状态准确预测的效能,并对其他航空设备以及机械设备的状态预测具有一定的借鉴意义。