含间隙和时变啮合刚度的渐开线齿轮副齿廓修形研究

在研究分析了轮齿和齿轮轴的弹性变形以及时变刚度、齿侧间隙、油膜等非线性因素的基础上,提出了考虑轮齿弹性振动以及单双齿啮合区变化的齿轮机构多体弹性非线性动力学模型。应用GEAR方法对建立的齿轮机构非线性动力学模型进行数值分析,研究了齿廓修形对齿轮机构动态响应的影响。     

含间隙和时变刚度的齿轮系统非线性动力学模型的研究

在研究分析了轮齿、齿轮轴的弹性变形、时变刚度、齿侧间隙、油膜等非线性因素基础上,提出了考虑轮齿弹性振动和单双齿啮合区变化的齿轮机构多体弹性非线性动力学模型.     

齿轮系统时变刚度和间隙非线性振动特性研究

以齿轮系统动力学和非线性动力学理论为基础，针对齿轮系统时变啮合刚度和齿侧间隙耦合作用的具体特点，建立了齿轮系统非线性模型，并用数值积分和数值仿真方法对其在某些参数域中进行了非线性振动研究。根据仿真结果得到一些有用的结论，是进一步进行多自由度齿轮系统和行星齿轮系统的非线性动力学研究的基础。     

基于非线性理论的齿轮机构动力学模型的建立及实验

在研究分析了轮齿的变啮合刚度和轮齿间的油膜动力学性能的基础上，提出了把此油膜看成是一个质量-弹簧-阻尼系统的假设，并运用弹流理论，分析了油膜厚度和油膜等效刚度，建立了相应的动力学模型和运动微分方程。采用GEAR方法求解非线性动力学微分方程组，并通过实验验证齿侧间隙对齿轮机构动态特性的影响。     

含时变刚度和齿侧间隙的斜齿轮系统非线性振动分析

针对斜齿轮系统的扭转振动,在考虑时变刚度和齿侧间隙这两种非线性因素的条件下,建立了斜齿轮副的单自由度纯扭模型。分析了时变刚度和齿侧间隙的非线性特征,并给出了表征方法。对含非线性因素的动力学模型中进行化简求解,分析了齿宽对时变刚度的影响,结果表明,若齿宽使轴向重合度εβ为1(整数)时,时变刚度的幅值约为零。分析了齿侧间隙的大小对系统的影响,对于斜齿轮副,在间隙60μm时,系统振动随间隙增加几乎呈线性增加,当间隙再增大时,系统振动对间隙的变化不敏感。     

间隙对含摩擦和时变刚度的齿轮系统动力学响应的影响

主要研究在考虑摩擦和时变刚度时,轮齿间隙对齿轮系统动力学响应的影响。建立常间隙、时变间隙和随机间隙三种不同的间隙形式。利用数值仿真的方法得到系统的幅频响应曲线和时间历程曲线。分析发现：①在低速时,随着摩擦因数的增大,系统响应的方均值和平均分量增大;并经过三次跳跃之后系统进入混沌运动状态;②时变间隙幅值增大导致系统提前进入混沌状态,而且随着时变幅值的增大跳转频率逐渐减小;时变间隙频率较小时,间隙对系统的影响较小;当时变间隙的频率较大时,系统在 =0.2,0.3时出现明显的共振响应,系统的响应以高频率分量4、5和6为主;③考虑随机间隙时,随着 的增大,齿轮系统响应的平均分量波动比较大。     

含间隙弹性机构动态特性分析

在含间隙刚性连杆机构动力学分析的基础上,建立了含间隙弹性连杆机构动力学模型,计入刚弹耦合作用及间隙对杆件弹性变形的影响,利用该方法对一弹性四连杆机构进行动力分析,采用较为简洁的迭代求解方法,通过算例讨论了几类机构的副反力,杆件变形的情况,计算结果表明,该方法是正确可行的。     

考虑挤压油膜的齿轮系统非线性动力学

在研究分析了轮齿间油膜的动力学性能的基础上,提出了把此油膜看成是一个质量－弹簧－阻尼系统的假设,并运用弹流理论,分析了油膜厚度和油膜等效刚度,建立了相应的动力学模型和运动微分方程,对运动微分方程进行了计算和分析,并比较了有油膜和没有油膜的齿轮动力学系统的动态响应的差异。     

含时变啮合刚度和齿距误差的斜齿轮动力学分析

齿轮是汽车变速器传动系统的动力载体,其动力学特性很大程度上决定了变速器的振动特性。利用时变接触线法求解了理论时变啮合刚度;结合齿距误差等内部激励建立了单对斜齿轮副弯扭轴耦合非线性动力学模型。采用龙格库塔方法进行数值求解,得到了斜齿轮副的振动响应时域曲线、频谱图。研究结果表明,时变啮合刚度越小,齿轮振动程度增大越迅速。加入齿距误差后,振动加速度时域特性以轴向振动变化最为明显,且齿距误差越小,振动强烈程度增大越缓慢。     

含间隙机构动力学研究若干问题

综合评述了含间隙机构的动力学建模方法、求解方法及其近几年在非线性动力学领域的发展,以及此类机构在控制方面的主要研究成果,同时本文对含间隙机构的未知领域提出了展望,提出了未来研究的主要方向。     

装配间隙对大型模锻压机结构刚度的影响

为了便于装配,在大型机械装备的安装中往往需要预留一定的间隙,根据大型模锻压机的几何特征和受载情况,利用有限元分析软件MSC.MARC对模锻压机在不同工况和不同装配间隙下的结构刚度进行模拟分析,探讨了装配间隙对模锻压机结构刚度的影响,并给出降低安装难度的合理间隙值范围.     

齿轮消隙功能实现探索

通过对弹簧消隙方法的分析,明确了齿轮消隙机构的本质,即给啮合齿轮加载力矩.基于这一原理,介绍了基于软硬件协同设计理念的智能摩擦消隙机构,展示了软件机械理念在智能齿轮消隙机构设计中的应用.     

履带车辆齿轮传动系统非线性振动特性研究

以齿轮系统动力学和非线性振动理论为基础,针对具有齿侧间隙和时变啮合刚度的某履带车辆齿轮传动系统,建立单自由度齿轮系统非线性振动模型,通过数值仿真方法求解并分析在不同档位下的振动特性,并对其在某些变量参数下进行了振动特性研究,所得结果既反映了动力学性能,又为下一步进行多自由度齿轮系统的非线性振动研究提供了有力的依据.     

Design and experimental study of a passive power-source-free stiffness-self-adjustable mechanism

Passive variable stiffness joints have unique advantages over active variable stiffness joints and are currently eliciting increased attention. Existing passive variable stiffness joints rely mainly on sensors and special control algorithms, resulting in a bandwidth-limited response speed of the joint. We propose a new passive power-source-free stiffness-self-adjustable mechanism that can be used as the elbow joint of a robot arm. The new mechanism does not require special stiffness regulating motors or sensors and can realize large-range self-adaptive adjustment of stiffness in a purely mechanical manner. The variable stiffness mechanism can automatically adjust joint stiffness in accordance with the magnitude of the payload, and this adjustment is a successful imitation of the stiffness adjustment characteristics of the human elbow. The response speed is high because sensors and control algorithms are not needed. The variable stiffness principle is explained, and the design of the variable stiffness mechanism is analyzed. A prototype is fabricated, and the associated hardware is set up to validate the analytical stiffness model and design experimentally.     

Nonlinear dynamics of a spur gear pair with time-varying stiffness and backlash based on incremental harmonic balance method

In this paper the incremental harmonic balance method (IHBM) is extended to analyze the nonlinear dynamics of a spur gear pair and some new results are obtained. At first the dynamical model of a spur gear pair is established, where the backlash, time-varying stiffness and static transmission error are all included. Here the time-varying stiffness and static transmission error are represented by the multi-order harmonic series through Fourier expansion. Based on the IHBM, the general forms of the periodic solutions for this system are founded, which is useful to obtain the solutions with arbitrary precision. And the difference between the frequency-response to the multi-order and single-order harmonic is analyzed. Then the effects of the multi-order harmonic on the kinds of the periodic solutions are also investigated by IHBM, and the comparison with the numerical solutions shows the validity of the proposed method. At last the influence of the damping ratio and the excitation amplitude on frequency-response curves is researched, which presents some useful information to analyze and/or control the dynamics of gear system.     

Effects of eccentricity defect on the nonlinear dynamic behavior of the mechanism clutch-helical two stage gear

This paper investigates the nonlinear dynamic behavior of an automotive clutch coupled with a helical two stage gear system. The nonlinear dynamic model is simulated by twenty seven degrees of freedom and including three types of nonlinearity: dry friction path, double stage stiffness and spline clearance. The utility of the proposed nonlinear model is illustrated by the industrial need to clearly identify the dynamic behavior of mechanical elements (shafts, bearings, gears, flywheel, pressure plate, hub of the clutch…) and reduce vibration. The governing nonlinear time varying motion equation formulated is resolved by the analytic Runge Kutta method.Then the modeling of the eccentricity defect located on the gear and the flywheel of the clutch is done. The effect of this defect on the nonlinear dynamic behavior of the system is investigated.     

基于凸轮机构的变刚度仿生柔性关节设计与分析

为满足足式机器人跑跳等动态运动对关节柔性及其变刚度特性的迫切要求,借鉴生物关节柔性特征与主被动刚度调节机理,创新地提出了一种基于凸轮机构的新型变刚度仿生柔性关节。基于关节刚度特性分析,构建了关节整体刚度模型,并针对影响关节刚度特性的各结构参数开展了系统优化设计,研制出了一款紧凑型高集成度关节样机。关节样机性能实验结果表明,基于凸轮机构的变刚度仿生柔性关节具备理想的关节输出力矩与刚度调节范围,可通过关节固有刚度特性与动态刚度特性的主被动融合控制,实现关节瞬时刚度的动态非线性精确调节,能够满足机器人动态运动对关节柔性与刚度的需求。     

Experimental studies on the effects of reduction in gear tooth stiffness and lubricant film thickness in a spur geared system

Gears are one of the most common mechanisms for transmitting power and motion and their usage can be found in numerous applications. Studies on gear teeth contacts have been considered as one of the most complicated applications in tribology. Depending on the application, the speed and load conditions of teeth may change triggering several types of failures on teeth surface such as wear, scuffing, micro-pitting and pitting. The above-mentioned faults influence changes in vibration and acoustic signals, due to changes in operating conditions such as increase in temperature and decrease in lubricant film thickness and specific film thickness. These abnormal changes result in cumulative effects on localised or distributed faults on load bearing surfaces of gears. Such damages cause reduction in tooth stiffness and severity of damage can be assessed by evaluating the same using vibration-based signals.This paper presents the results of experimental investigations carried out to assess wear in spur gears of back-to-back gearbox under accelerated test conditions. The studies considered the estimation of operating conditions such as film thickness and their effects on the fault growth on teeth surface. Modal testing experiments have been carried out on the same gear starting from healthy to worn out conditions to quantify wear damage. The results provide a good understanding of dependent roles of gearbox operating conditions and vibration parameters as measures for effective assessment of wear in spur gears.