双圆弧齿轮的静态和动态接触模型

基于有限元软件ANSYS建立了双圆弧齿轮静态和动态接触的计算模型，讨论了在真实转动情况下计算齿轮接触应力、应变应该注意的一些事项。介绍了静态接触模型中约束和载荷的处理方法，以及动态模型中施加相当于转矩的跟随载荷的具体方法，讨论了刚体在静态和动态模型中的作用和影响。通过对静态和动态模型计算结果的比较，说明了动态模型方法是可行的。     

基于ARM和DSP的齿轮噪声测试系统

为了解决齿轮噪声传统测量方法受人为因素影响较大的弊端,开发了一套基于ARM和DSP芯片的便携式齿轮噪声测试系统,利用DSP强大的运算能力完成了噪声信号的采集与数据的预处理;基于ARM下的嵌入式系统操作平台WinCE6.0开发了一套齿轮噪声信号分析及图形显示软件,结合触摸屏系统完成了测试参数的输入和通信设置,并在北京齿轮总厂进行了相关的实验。研究结果表明,该系统可以分析齿轮毛刺等齿轮噪声信号,可用于齿轮加工工艺的分析。     

点蚀故障对齿轮传动系统噪声的影响

针对不同数滚机床齿轮齿面点蚀故障严重程度对齿轮传动系统噪声的影响,基于赫兹理论力学模型,运用ABAQUS创建了齿轮副的应力仿真分析模型,求解在未点蚀及不同点蚀故障严重程度下齿面最大接触应力,并对比了传动扭矩对不同点蚀故模型最大接触应力的影响。开展了不同齿面点蚀故障齿轮模拟工况下的噪声测试实验,通过对比齿轮副试样噪声的敏感性分析不同点蚀故障严重程度的影响。有限元结果表明,传动扭矩与齿面最大接触应力呈线性关系,点蚀故障越严重,齿面点蚀区域接触冲击应力越大;齿轮故障噪声测试实验研究结果则表明,基于微点蚀、点蚀失效形式之间存在的竞争机制,点蚀故障越严重,对应的噪声曲线峰值越大;随着齿轮负载、转速的增大,点蚀故障齿轮噪声也逐渐增大。     

Simulating gear and bearing interactions in the presence of faults: Part I. The combined gear bearing dynamic model and the simulation of localised bearing faults

This paper presents a simulation model for a gearbox test rig, in which a range of bearing faults can be implemented. Bearing faults sometimes manifest themselves by their interaction with meshing gears, and to simulate this it is necessary to model a whole system of gears and shafts supported in bearings. This has now been done for an experimental test rig through the incorporation of a time-varying, non-linear stiffness bearing model into a previously developed gear model. The incorporated bearing model is based on Hertzian contact theory, which relates the raceway displacement to the bearing load, and also accounts for the slippage between the elements. It has the capacity to model localised spalls (inner race, outer race and rolling elements), which are discussed in this part of the paper and extended inner and outer race faults (rough surfaces), which are discussed in part II. Even though the whole gearbox has not been modelled in detail, the non-linear time-varying gear-meshing operation is modelled in some detail. Both simulated and experimental localised fault signals (acceleration signals) were subjected to the same diagnostic techniques; namely spectrum comparisons, Spectral Kurtosis (SK) analysis and envelope analysis. The processed simulated signals showed a similar pattern to that observed in their measured counterparts and were found to have a characteristic, referred to in the literature as double pulses, corresponding to entry into and exit from the localised fault. The simulation model will be useful for producing typical fault signals from gearboxes to test new diagnostic algorithms, and possibly prognostic algorithms.     

Evaluation of tire contact properties using nondestructive testing. Part 2: Experimental determination and fuzzy model of the contact parch in the static state

The paper presents the results of experimental determination of the contact parch area of various automobile tires in response to normal loading on the wheel and tire inflation pressure. The data are obtained for test bench conditions by visual processing of tread footprint. The test program covers five tire types of different manufacturers with different rubber blends. The experimental results are used to construct regression dependences and a multipurpose fuzzy model for determination of the contact parch area in response to loading on the wheel and tire inflation pressure.     

Experimental evaluation of some current injection-voltage reading patterns in electrical impedance tomography (EIT) and comparison to simulation results - Case study: Large scales

Each electrical impedance tomography system to be prosper, usually would had its own current injection and voltage reading patterns within domains under test. So in different domains, each of sensing patterns have different performances. In industrial application for conductive carrier-phases and in large domains, impedance imaging of real phantoms would be advisable candidate for better performance. Therefore in this study, performance of five sensing patterns in a large scale (outer diameter of 700 mm) were evaluated. Based on the sensing patterns, parameters such as; applicability in the domain and online mode, voltage signal-to-noise ratio (SNR), boundary voltage changes (BVC), sensitivity distributions, size error (SE) and ringing, in different object locations were studied by simulation and experimentally. The results illustrated that there is a significant difference between the reconstruction images of simulation and experimental data in the patterns with low SNR. Also, in a pattern with high SNR, due to the low BVC, the desired performance was not achieved. The highest correlation in the image reconstruction of the simulation and experimental data was obtained in the Opposite-Adjacent pattern with high SNR and BVC. The results show that the selection of this sensing pattern can improve the object's SE up to 0.68%.