裂纹故障对行星齿轮传动系统动力学特性的影响

针对行星传动装置动态特性复杂、故障率高的问题,拟从动力学角度探索行星传动系统的故障机理。采用改进能量法,仿真分析正常与含裂纹齿轮时变啮合刚度,考虑时变啮合参数影响,运用集中参数法建立了行星齿轮传动系统动力学模型;求解得到了正常与含故障齿轮传动系统动态响应,并对比分析了裂纹故障对动力学特性的影响;通过台架实验,分析了裂纹故障对齿轮动态响应的影响,结合小波分析与EEMD方法对齿轮振动信号进行频谱分析,并对比分析了正常与故障齿轮的频域特性差异,揭示了行星齿轮传动系统的故障机理。研究表明:所建立的动力学模型精度较高,能够很好地描述含故障齿轮传动系统的动力学特性;由于裂纹故障引起传动系统振动的调制效应,导致在齿轮啮合频率附近出现明显边频带,故障齿轮箱的振动能量主要集中在高频段。     

含摩擦力的行星齿轮传动系统非线性动力学模型

建立了一种考虑摩擦力、时变啮合刚度、齿侧间隙和综合啮合误差的2K-H型行星齿轮平移-扭转耦合非线性动力学模型。分析计算了啮合齿对间的相对位移,根据啮合区啮合齿对数不断变化的特点,推导出不同啮合齿对间摩擦力力臂计算公式,考虑了双齿啮合区的齿面摩擦力对齿轮系统振动的影响,推导了系统多间隙,变参数和多自由度的动力学微分方程组。最后运用变步长Gill积分法求解系统多自由度间隙型非线性微分方程组,得到了考虑滑动摩擦力影响时系统的振动响应。     

双裂纹转子系统非线性动力学特性研究

从断裂力学理论出发,考虑了裂纹强度因子中剪力因素在裂纹截面处的影响,通过建立的裂纹转子精细有限元动力学模型,分析了不同裂纹位置对双裂纹转子系统亚临界、主共振区,及超临界转速下的非线性动力学响应,以及双裂纹转子系统不同裂纹方向角对双裂纹转子系统动力学响应的影响,结果为多裂纹转子系统故障识别提供了理论依据。     

机车齿轮箱齿根裂纹故障特征提取方法研究

齿轮箱是机车传动系统的重要部件。诊断齿轮箱齿根裂纹故障有助于减少或者避免列车运行事故。基于图傅里叶变换方法对齿轮箱传动系统齿根裂纹进行故障诊断时,由于受到高斯白噪声的影响,处理后故障特征频率不够明显。提出一种基于复Morlet小波梳状滤波器以及图谱理论相结合的齿轮箱传动系统齿根裂纹故障诊断方法。首先,通过复Morlet小波簇梳状滤波器对含有齿轮箱齿根裂纹故障信息的信号进行滤波以及包络解调处理;然后,通过图谱傅里叶变换方法将信号中含有的冲击分量集中到图谱域的高阶区域,从而提取出信号中所含有的冲击成分,可为齿轮箱齿根裂纹故障诊断提供有力依据。通过运用所提出方法对含有齿根裂纹的机车齿轮箱振动信号进行分析,证明了其有效性。     

一种改进的齿轮非线性动力学模型

在考虑齿面摩擦、齿轮时变啮合刚度和齿侧间隙的情况下,推导出了改正的齿轮副系统的非线性动力学模型,应用符号运算软件,编写符号运算程序,得到了齿轮副非线性振动微分方程。该模型在计算摩擦力时,考虑了载荷在啮合区的动态分配,并根据啮合区单双齿交替的特点提出用周期扩大法建立摩擦力、齿轮时变刚度的模型,改正的齿轮非线性动力学模型是一个周期系数分段线性的非自治系统,与以前所建立的模型相比,该模型的参变系数是具有相同周期的周期函数,新的齿轮非线性动力学模型的建立为求解时变的齿轮动力学方程近似解析解带来方便。     

故障旋转机械非线性动力学近期研究综述

重点介绍"故障旋转机械非线性动力学的理论与实验"的若干研究结果.说明了研究故障旋转机械动力学的意义,讨论了有单一故障(裂纹、碰摩、松动和油膜震荡等)或耦合故障(裂纹和碰摩、裂纹和松动、碰摩和松动等)的转子系统非线性动力学的某些特性、转子系统故障发生与发展的慢变与突变过程及其特点、故障转子系统的可靠性分析若干理论问题,以及抑制转子系统振动的若干措施与方法等.     

滑动轴承-裂纹转子系统非线性动力学特性分析

在裂纹转子非线性动力学特性分析中考虑了非线性油膜力的影响,在此基础上建立了单盘Jeffcott裂纹转子的非线性动力学模型,裂纹模型采用非线性涡动模型,菲线性油膜力通过数据库方法获得.利用数值计算方法分析了裂纹转子系统随转速w/w0、相对刚度减小量△kε等参数变化的动力学特性和动力学行为.结果表明在非线性油膜力的作用下,△kε较小时,响应中出现不可公约的谐波分量导致系统在亚临界转速区出现概周期运动,△kε较大时,系统产生丰富的非线性动力学行为;在不同转速下,系统出现多种形式的周期运动、分岔、概周期运动和混沌运动.     

裂纹转子非线性振动实验研究

对轴中央含有横向裂纹的Jeffcott转子系统,在转子试验台上进行了非线性动力学特性的模拟实验.通过对比裂纹轴与完好轴在不同转速时的振动特征可以看出,裂纹轴的临界转速有明显降低,而且二阶和高阶频率成分在系统通过1/2临界转速时变得非常明显,在亚临界转速区,轴心轨迹出现明显的双环形结构.这些与理论分析的结果定性相符.     

含磨损故障的齿轮传动系统非线性动力学特性

为揭示磨损故障对于齿轮传动系统非线性动态特性的影响,利用Archard和Weber-Banaschek公式分别计算了齿面动态累积磨损量和磨损齿轮对的时变啮合刚度。建立含有非线性齿侧间隙、内部误差激励和含磨损故障的时变啮合刚度的三自由度齿轮传动系统平移-扭转耦合动力学方程。采用变步长Gill积分方法对动力学模型进行了数值仿真分析,以系统的激励频率为分岔参数,计算系统的对应的分岔图;引入GRAM-SCHMIDT方法对系统的Jacobi矩阵进行正交化处理,计算系统的李雅普诺夫指数谱,同时结合Poincaré映射图和功率谱验证了李雅普诺夫指数谱和分岔图计算结果的正确性。通过研究发现了系统内部存在的丰富非线性现象,包括倍周期分岔途径、阵发性途径和多种拟周期通过锁相进入混沌的现象;在系统经由拟周期进入混沌的过程中发现了交替出现的拟周期与锁相现象以及拟周期运动时功率谱分量存在的Farey序列现象。研究结果表明含有磨损故障的齿轮传动系统具有非常复杂的动力学特性,而系统由周期运动进入混沌运动的途径也是丰富多样的。     

铁道车辆含故障参数的非线性动力学模型

随着铁路高速重载的提出,货车转向架的非线性动力学问题日益突出,货车系统动力学性能和安全运行已是亟需研究的课题。本文分析三大件转向架容易损坏并发生故障的关键部件的故障形式,重点分析了二系悬挂减振装置中的磨耗故障的发生。建立了含有故障参数的39自由度货车车辆非线性动力学模型。通过对其进行大量的数值仿真,考察系统动力学响应和相应故障参数变化之间的关系,以此为基础探讨研究故障机理的新思路。     

Differential diagnosis of spall versus cracks in the gear tooth fillet region

This paper presents a technique to differentially diagnose two localized gear tooth faults: a spall and a crack in the gear tooth fillet region. These faults could have very different prognoses, but existing diagnostic techniques only indicate the presence of local tooth faults without being able to differentiate between a spall and a crack. The effects of spalls and cracks on the behavior/response of gear assemblies were studied using static and dynamic simulation models. Changes in the kinematics of a pair of meshing gears due to a gear tooth root crack and a tooth flank spall were compared using a static analysis model. The difference in the variation of the transmission error caused by the two faults reveals their characteristics. The effect of a tooth crack depends on the change in stiffness of the tooth, while the effect of a spall is predominantly determined by the geometry of the fault. The effect of the faults on the gear dynamics was studied by simulating the transmission error in a lumped parameter dynamic model. A technique had previously been proposed to detect spalls, using the cepstrum to detect a negative echo in the signal (from entry into and exit from the spall). In the authors’ simulations, echoes were detected with both types of fault, but their different characteristics should allow differential diagnosis. These concepts are presented prior to experimental validation in hopes that the diagnostic techniques will be useful in the failure analysis community prior to the validation by ongoing experimental testing of the concepts and the evaluation of how metallurgical defects may influence fault development and detection.     

基于传动误差检测法的早期齿轮磨损故障诊断

摘 要：针对齿轮系统在复杂结构复杂工况下早期故障难诊断的问题,借鉴精密机械中检测齿轮安装误差和加工误差的传动误差检测法,建立含故障的二级齿轮系统传动误差信号模型,分析中间轴齿轮早期单齿齿面磨损对齿轮系统传动误差的影响及特征规律。经齿轮传动系统实验台实测信号研究结果证明：传动误差信号信噪比高,能够有效识别复杂齿轮系统中齿轮早期磨损故障。     

Experimental and numerical investigation of fatigue crack growth in the cracked gear tooth

The numerical simulation was conducted to analyse the fatigue crack growth in gear with the finite element codes ansys (ANSYS, Inc. Canonsburg, Pennsylvania, USA.) and franc 3d (Fracture Analysis Consultants, Inc. Ithaca, New York, USA.), and the corresponding fatigue test was also carried out. During the simulation, the location of maximal stress induced by the external force was first determined by the code ansys , and then the obtained results were imported into the franc 3d to analyse the crack growth. The analysed results were input into the codes ansys and franc 3d again to compute the stress and the stress intensity factor in the following steps. After several rounds of analysis, the results of the fatigue crack propagation were obtained. The investigations show that the crack mode I is dominant during the crack growth and the stress intensity factor K_I raises with increase of crack growth length and a series of quarter‐elliptical cross sections of the ruptured gear tooth are obtained. The simulation results are in good accordance with experimental findings.     

二级圆柱斜齿轮系统耦合动态响应分析

应用集中参数法建立了一种计及时变啮合刚度、齿侧间隙、传动误差的二级圆柱斜齿轮传动系统弯－扭－轴－摆耦合动力学模型,推导并求解了传动系统的动力学微分方程组,得到了二级圆柱斜齿轮传动系统的动力响应。基于有限元法建立了箱体的动力学分析模型,在得到传动系统动态响应及轴承结合部动力学参数数值基础上,对箱体进行了动力响应分析。在将齿轮系统划分为传动系统与箱体两个子系统的基础上,实现了对整个齿轮系统的动力学分析。     

Experimental investigation of spur gear tooth mesh stiffness in the presence of crack using photoelasticity technique

Gear mesh stiffness plays a very important role in gear dynamics and it varies in the presence of gear fault such as crack. The measurement of stress intensity factor can lead to the determination of gear tooth mesh stiffness variation in the presence of crack in a spur gear system. In this paper, the technique of conventional photoelasticity has been revisited to explore the possibility of using it as a supplementary technique to experimentally measure the variation of gear mesh stiffness. An attempt has been made to calculate the variation of mesh stiffness for a pinion having a cracked tooth and a gear tooth with no crack of a spur gear pair. An analytical methodology based on elastic strain energy method in conjunction with total potential energy model has been adopted and implemented within the mesh stiffness calculations. To visualize the state of stress in a structure using finite element and other currently available methods, photoelasticity is considered to be one of the oldest and most developed experimental technique. An experimental methodology based on conventional photo-elasticity technique for computing stress intensity factor (SIF) for cracked spur gear tooth is presented for different single tooth contact position and crack length. The relation between contact position, crack length, crack configuration, SIF and the variation of total effective mesh stiffness have been quantified. Finally, a comparison has been made and the results obtained from finite element method (FEM) based on linear elastic fracture mechanics (LEFM), analytical method and proposed experimental method has been outlined.     

基于频谱编辑和调制信号双谱的齿轮裂纹故障诊断

齿轮产生裂纹故障时,其振动信号中的周期性故障冲击成分易被其他旋转部件的谐波信号以及背景噪声淹没,导致故障特征难以提取.针对这一问题,首先用改进的频谱编辑方法对原始信号中谐波分量进行抑制,提高信噪比;然后对编辑后的信号进行双谱分析,采用相邻切片融合平均的方法对双谱进行降噪,从降噪后双谱中选取故障特征频率明显的切片进行组合...     

Influence of different load models on gear crack path shapes and fatigue lives

A computational model for determination of the service life of gears with regard to bending fatigue at gear tooth root is presented. In conventional fatigue models of the gear tooth root, it is usual to approximate actual gear load with a pulsating force acting at the highest point of the single tooth contact. However, in actual gear operation, the magnitude as well as the position of the force changes as the gear rotates. A study to determine the effect of moving gear tooth load on the gear service life is performed. The fatigue process leading to tooth breakage is divided into crack‐initiation and crack‐propagation period. The critical plane damage model has been used to determine the number of stress cycles required for the fatigue crack initiation. The finite‐element method and linear elastic fracture mechanics theories are then used for the further simulation of the fatigue crack growth.     

内激励作用下齿轮箱动态响应与振动噪声分析

综合考虑齿轮时变啮合刚度及齿轮误差等内部激励的影响,建立了齿轮箱稳态动响应分析模型。采用模态叠加法进行求解,得到了齿轮箱节点位移动响应时域历程,对激励中各谐波成分对齿轮箱动响应的影响做出了分析。采用声固耦合的方法对齿轮箱噪声辐射进行求解,得到了齿轮箱噪声谱。计算了齿轮箱各板面对声场总声压的贡献度,依据板面贡献度计算结果,提出了模型改进方案,并对各改进方案的降噪效果做出了评估,为齿轮箱的设计提供了理论依据     

含裂纹故障的齿轮系统动力学特性研究及其故障特征分析

考虑齿轮的时变啮合刚度、传动误差和轴承支撑刚度的影响,建立含齿根裂纹故障的齿轮系统多自由度力学模型,基于动力学方法对其故障机理进行研究。通过材料力学的方法计算齿轮在正常和含裂纹两种情况下的啮合刚度,对比两种刚度曲线的变化趋势,便于进行精确的动力学特性分析;对建立的模型求解系统的动态响应,结果表明当齿根存在裂纹时,其时域波形中会出现周期性的冲击现象,频谱中在啮合频率的基频及其倍频等地方形成一系列等间隔的边频谱线,其间隔大小等于故障齿轮的转频;这些边频成分幅值较低,能量分散且分布不均匀,在不同频带的幅值大小存在差异。针对上述特点,通过正交小波包方法对信号的频带进行分解,应用倒频谱分析各子频带信号的边频成分;结果表明,该方法能够有效的提高信号的信噪比,有助于识别和提取信号中由裂纹故障引起的边频成分。