行星齿轮啮合刚度对其振动特性的影响

建立了单级直齿行星齿轮传动多自由度数学模型。在该系统中,根据行星齿轮固有频率和振动模态的特点,指导了特征值对于啮合刚度的敏感度公式及其与啮合应变能之间的关系式。分析结果表明,啮合刚度对两个旋转模态、两组位移模态和两个行星模态的固有特性影响较大;根据啮合应变能分布,可以清楚地了解啮合刚度变化对于系统固有特性的影响。     

A dynamic-model-based fault diagnosis method for a wind turbine planetary gearbox using a deep learning network

The planetary gearbox is a critical part of wind turbines, and has great significance for their safety and reliability. Intelligent fault diagnosis methods for these gearboxes have made some achievements based on the availability of large quantities of labeled data. However, the data collected from the diagnosed devices are always unlabeled, and the acquisition of fault data from real gearboxes is time-consuming and laborious. As some gearbox faults can be conveniently simulated by a relatively precise dynamic model, the data from dynamic simulation containing some features are related to those from the actual machines. As a potential tool, transfer learning adapts a network trained in a source domain to its application in a target domain. Therefore, a novel fault diagnosis method combining transfer learning with dynamic model is proposed to identify the health conditions of planetary gearboxes. In the method, a modified lumped-parameter dynamic model of a planetary gear train is established to simulate the resultant vibration signal, while an optimized deep transfer learning network based on a one-dimensional convolutional neural network is built to extract domain-invariant features from different domains to achieve fault classification. Various groups of transfer diagnosis experiments of planetary gearboxes are carried out, and the experimental results demonstrate the effectiveness and the reliability of both the dynamic model and the proposed method.     

Residual signal feature extraction for gearbox planetary stage fault detection

Faults in planetary gears and related bearings, e.g. planet bearings and planet carrier bearings, pose inherent difficulties on their accurate and consistent detection associated mainly to the low energy in slow rotating stages and the operating complexity of planetary gearboxes. In this work, statistical features measuring the signal energy and Gaussianity are calculated from the residual signals between each pair from the first to the fifth tooth mesh frequency of the meshing process in a multi‐stage wind turbine gearbox. The suggested algorithm includes resampling from time to angular domain, identification of the expected spectral signature for proper residual signal calculation and filtering of any frequency component not related to the planetary stage. Two field cases of planet carrier bearing defect and planet wheel spalling are presented and discussed, showing the efficiency of the followed approach and the possibility of characterizing a fault as localized or distributed. Copyright © 2017 John Wiley & Sons, Ltd.     

基于遗传算法大功率倒伞曝气机行星减速齿轮箱的优化设计

遗传算法是一种新的设计方法,对于复杂系统的优化设计其鲁棒性好。通过对遗传算法的研究,构建了大功率倒伞曝气机行星减速齿轮箱数学模型,通过编码的方法对其轮系的离散变量、整型变量进行了寻优设计,解决了大功率倒伞曝气机行星齿轮箱优化设计的问题。     

Blockchain assisted encryption scheme for intellectual share estimation using medical research data

Recently, blockchain utilization with advanced encryption and decryption has gained improved attention over diverse applications. Especially in the medical field, big data storage requires an effective medium for managing user data with high confidentiality. The existing research presents diverse encryption algorithms, but certain drawbacks include sensitive information leakage, ineffective data integrity verification, and increased computational cost and time. The proposed work develops an effective blockchain mechanism for secured data storage to conquer these limitations. This article secures the medical research data from different team members for intellectual share estimation. Initially, the registration process involves user details such as name, contact number, age and so on. Next, a digital signature is generated for every registered user using the SHA-256 hash algorithm. During data uploading, the data is encrypted using elliptic curve Diffie Hellman encryption scheme to promote security. The audio and video files are stored in inter planetary file system, and texts are stored in the blockchain. The users can retrieve the stored data from the blockchain using the encryption key. The identities and associated public keys are verified using a smart contract to validate the user certificate. Next, a decision form is made to show the polling mechanism using item preference ranking for other users viewing the data. The proposed mechanism ensures intellectual shares for all the users associated with a specified project. The performances are analyzed using PYTHON, and the encryption time obtained in the proposed model is 0.85 s at 140 security bit level.     

精密钢球行星减速机构传动分析及仿真

精密钢球行星减速机构是一种高效节能的摆线类传动形式,设计一种二级摆线钢球减速机构,其利用减速钢球作为传动介质,在外摆线槽和内摆线槽构成的循环滚道中进行无间隙啮合传动,分析摆线减速机构的传动原理,对不同类型的减速机构的传动比进行计算。利用动力学仿真软件ADAMS平台,做二级摆线减速机构的运动学模拟仿真,得到运动过程中行星盘和摆线盘的角速度和角加速度曲线,验证分析减速机构的运动平稳性和传动合理性,为二级摆线减速机构的结构优化设计和减速比设计提供理论依据。     

基于有限元的三辊行星轧制力预测及分析

为预测三辊行星轧制力,建立了三维热力耦合有限元模型,用均匀设计法安排有限元模拟样本,采用基于LM算法的BP神经网络学习有限元轧制力结果,确定了轧制参数与轧制力的映射关系,并根据训练后的神经网络分析了摩擦系数、轧辊偏转角和轧辊转速对轧制力影响．预测结果表明：摩擦系数和轧辊偏转角对轧制力影响是多方面的,在高轧辊转速时,较大的摩擦系数有利于降低轧制力．     

冲击载荷作用下行星齿轮传动系统故障响应特性研究

掘进机工作过程中,由于煤、岩体强度不均匀,导致截割头常受到瞬时冲击载荷作用,造成截割减速器断齿故障频发。建立了行星齿轮系统动力学模型,研究了冲击载荷、断齿故障对系统响应的影响。结果表明,冲击载荷作用下行星齿轮发生断齿故障时,齿圈约束反力时域均值增大,时域波形中除了包含断齿故障产生的周期性冲击成分,还包含载荷突变产生的冲击。     

Effects of kinds of oil on power transmission: Efficiency of planetary traction drives

One of the most interesting problems in traction drives is the analysis of their power transmission efficiency. Using an experimental two-disk machine and two planetary traction drives, together with fourteen test oils, it is shown that the power transmission efficiency can increase up to 97% in the case of an experimental planetary traction drive. The synthetic traction oils bring about a lower efficiency than mineral oils when the output torque is small. This is ascribed to their higher traction coefficients which cause larger friction in the rolling bearings which support the rolling elements.     

行星齿轮变速机构方案设计的杠杆分析法

介绍了利用杠杆分析法进行行星齿轮变速机构方案设计的过程及方法,对汽车自动变速器的设计具有一定的指导意义.