传动系统振动对载货汽车通过噪声的影响机理研究

对汽车通过噪声源进行论述,利用对某载货汽车通过噪声的研究阐述传动系统振动对通过噪声的影响。利用摸底试验、传动轴模态计算和模态试验等方法,确定试验样车通过噪声大的原因为变速器副箱齿轮啮合激励为激振源,且3根传动轴耦合共振使噪声扩大。结合噪声原因分析和方案可行性分析,提出采用改变传动轴空腔结构以消除传动轴空腔扩音的方案,从而使试验样车的通过噪声显著降低。

基于同态滤波技术的提升机传动系统振动故障分析

本文基于同态滤波技术对提升机卷筒轴轴承故障诊断,准确诊断出卷筒轴振动的主要原因,为实现煤矿机械设备维修提供了依据。对煤矿大型关键设备进行诊断,实现由定期维修到预知维修的转变,是一项值得推广应用的新技术。

考虑磨损故障的双渐开线齿轮传动系统动态特性研究

针对目前双渐开线齿轮(DIG)研究过程中齿廓磨损对双渐开线齿轮动态特性的影响问题,对考虑磨损故障的双渐开线齿轮传动系统动态特性进行了研究。首先,进行了双渐开线齿轮接触线长度与齿面载荷计算,考虑相对滑移距离,建立了等效接触模型;然后,进行了双渐开线齿轮齿面累积磨损量、齿轮齿面累积磨损深度的计算,建立了双渐开线齿轮啮合刚度计算模型,进行了磨损故障的双渐开线齿轮刚度的计算;最后,以一对双渐开线齿轮为研究对象,采用集中质量法建立了6自由度动力学模型,研究了齿面磨损对双渐开线齿轮动力学特性的影响。研究结果表明:在运行1×104次载荷循环后,混合弹流润滑状态下,双渐开线齿轮与普通渐开线齿轮(CIG)在节线附近齿根位置的最大累计磨损量差值为0.00207μm,且双渐开线齿轮节线靠近齿顶位置的磨损小于普通渐开线齿轮的磨损;双渐开线齿轮系统在磨损后振动加速度幅值小于普通渐开线斜齿轮的幅值。通过对不同磨损情况下的时域响应进行研究,发现磨损导致双渐开线齿轮传动系统的振动幅值增大。

基于KL-CEEMD的风机传动系统故障诊断方法研究

互补集合平均经验模态分解(complementary ensemble empirical model decomposition,CEEMD)作为一种时频特征分析方法,可以较好地提取复杂非线性非平稳信号的故障特征,但其存在虚假分量,很大程度限制诊断过程中的准确性。针对该问题,提出一种基于KL散度(Kullback-Leibler divergence,KLD)的CEEMD虚假分量识别方法(KL-CEEMD)。该方法在原有CEEMD方法基础之上,进一步计算各分量IMF与原信号之间的KL散度值,从而量化各分量与原信号之间的相关性。最后通过对各个IMF的KL散度值进行聚类分析,找出虚假分量和真实分量,最终解决CEEMD的虚假分量问题。为验证KL-CEEMD的有效性,研究搭建风力机传动系统振动试验台,基于该方法对实验台实验数据以及仿真数据进行验证性研究,最终证明所提方法可以很好改善CEEMD的虚假分量问题,能够有效提取出故障信号的真实特性。

分度圆裂纹齿轮啮合刚度计算及啮合动态特性分析

为了探究分度圆裂纹对齿轮传动系统产生的影响,利用改进能量法计算分度圆裂纹齿轮的啮合刚度,结合动力学模型对齿轮传动系统进行了动态特性分析。首先,将齿轮的齿根圆视为悬臂梁起点,把分度圆裂纹按照其齿廓投影位置分为了3种情况;然后,利用改进能量法理论计算了不同裂纹情况下的齿轮啮合刚度;最后,在啮合刚度的基础上,建立了齿轮系统的六自由度动力学模型,分析了不同裂纹情况下的齿轮系统的动态特性。仿真结果表明:相比于正常齿轮,分度圆裂纹为2.5 mm时,齿轮的啮合刚度最多下降14.3%,传递误差最多升高12.2%,齿间啮合力最多下降3.6%,啮合摩擦力最多下降14.8%;随着裂纹长度增大,齿轮啮合刚度逐渐降低,传递误差随之增大,齿间啮合力和啮合摩擦力逐渐降低。研究结果表明:由于裂纹的影响,齿轮传动系统会受到周期性冲击。

Super-harmonic resonance of gear transmission system under stick-slip vibration in high-speed train

This work deals with super-harmonic responses and the stabilities of a gear transmission system of a high-speed train under the stick-slip oscillation of the wheel-set.The dynamic model of the system is developed with consideration on the factors including the time-varying system stiffness,the transmission error,the tooth backlash and the self-excited excitation of the wheel-set.The frequency-response equation of the system at super-harmonic resonance is obtained by the multiple scales method,and the stabilities of the system are analyzed using the perturbation theory.Complex nonlinear behaviors of the system including multi-valued solutions,jump phenomenon,hardening stiffness are found.The effects of the equivalent damping and the loads of the system under the stick-slip oscillation are analyzed.It shows that the change of the load can obviously influence the resonance frequency of the system and have little effect on the steady-state response amplitude of the system.The damping of the system has a negative effect,opposite to the load.The synthetic damping of the system composed of meshing damping and equivalent damping may be less than zero when the wheel-set has a large slippage,and the system loses its stability owing to the Hopf bifurcation.Analytical results are validated by numerical simulations.

Designer在龙门机床部件优化中的应用分析

本文利用AVL公司的EXCITE—designer软件,建立传动系统扭转振动的模型,对比了安装减振器前后传动系统扭转振动特性的变化并分析其形成原理。计算结果表明:减振器能明显改善曲轴扭振特性,并且研究得出硅油减振器比橡胶减振器的性能好很多。

ACTIVE VIBRATION CONTROL OF A CANTILEVER BEAM USING PIEZOELECTRIC SENSORS AND ACTUATORS

The topic of vibration control with distributed actuators has been the subject of many researches. This paper is concerned with the vibration control of a cantilever beam equipped with piezoelectric ceramics as sensors and actuators. One piezoelectric ceramic is bonded to the structure and provides control input for the structure, while the other piezoelectric ceramic provides the feedback signal. An approach to identification and control is presented. Observation spillover is eliminated by prefiltering the sensor data. A procedure used to determine actuator and sensor location, is discussed based on the modes to be controlled. Finally, the experimental results are presented to verify the proposed method.

Torsional Vibration Analysis of an FR Driveline System

Towing tractor drivelines are lightly damped non-linear systems. Interactions between components can cause dynamic behavors such as gear gap impact in gear transmissions, shuffle and clonk phenomena in driveline. The torsional vibration of driveline has an important effect on grand engineering vehicle vibration and noise. Through analyzing torsional vibration equations of driveline, torsional vibration model of driveline is developed by using Matlab/Simulink software, Shuffle and clonk phenomena are observed in torsional vibration. The modeling method of analysizing driveline torsional vibration can be used to research and improve similar engineering vehicle driveline behavors.

Theoretical and experimental study on non-linear vibration characteristic of gear transmission system

In order to investigate the vibration of gear transmission system with clearance, a vibratory test-bed of the gear transmission system was designed. The non-linear dynamic model of the system was presented, with consideration of the effects of nonlinear dynamic gear mesh excitation, flexible rotors and bearings. Integration method was used to investigate the non-linear dynamic response of the system. The results imply that when the mesh frequency is near the natural frequency of gear pair, it is the first primary resonance, the bifurcation appears, and the vibration becomes to be chaotic motion rapidly. When the speed is close to the natural frequency of the first-order bending vibration, it is the second primary resonance, the periodic motion changes to chaos by period doubling bifurcation. The vibratory measurement of test-bed of the gear transmission system was performed. Accelerometers were employed to measure the high frequency vibration. Experimental results show that the vibration acceleration of the gear transmission system includes mesh frequency and sideband. The numerical calculation results of low speed can be validated by experimental results basically. It means that the presented non-linear dynamic model of the gear transmission system is right.