多轴系耦合作用下齿轮系统转子裂纹故障的振动特性研究

为了探究多轴系耦合齿轮系统中的转子裂纹故障与单轴系转子裂纹故障振动响应特性的异同点,基于Jones轴承建模理论,建立滚动轴承的拟静力学模型;利用Timoshenko梁单元建立传动轴的有限元模型;考虑时变啮合刚度、齿轮传递误差、陀螺效应等因素,利用集中参数法建立齿轮副的动力学模型。将轴承、传动轴与齿轮副模型进行集成,建立齿轮系统非线性动力学模型;利用能量释放率理论与应力强度因子为零法分析裂纹转子单元的呼吸效应,利用Newmark-?数值积分法对转子裂纹故障进行动力学仿真,研究转子裂纹故障的振动响应特征。结果表明：与单轴系转子裂纹故障不同,当齿轮系统发生转子裂纹故障时,由于齿轮啮合的引起的耦合效应及转子裂纹引起的呼吸效应,时域响应表现出明显的幅值调制现象,频域中转频及其2倍频幅值增加明显,在啮合频率处伴有明显的边频带。研究结果为齿轮系统转子裂纹故障的监测与诊断提供了理论基础。     

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。     

多轴系耦合作用下齿轮系统转子裂纹故障的振动特性研究

为了探究多轴系耦合齿轮系统中的转子裂纹故障与单轴系转子裂纹故障振动响应特性的异同点,基于Jones轴承建模理论,建立滚动轴承的拟静力学模型;利用Timoshenko梁单元建立传动轴的有限元模型;考虑时变啮合刚度、齿轮传递误差、陀螺效应等因素,利用集中参数法建立齿轮副的动力学模型。将轴承、传动轴与齿轮副模型进行集成,建立齿轮系统非线性动力学模型;利用能量释放率理论与应力强度因子为零法分析裂纹转子单元的呼吸效应,利用Newmark-β数值积分法对转子裂纹故障进行动力学仿真,研究转子裂纹故障的振动响应特征。结果表明:与单轴转子系统转子裂纹的振动响应特征不同,当齿轮系统发生转子裂纹故障时,由于齿轮啮合的引起的耦合效应及转子裂纹引起的呼吸效应,时域响应表现出明显的幅值调制现象,频域中转频及其2倍频幅值增加明显,在啮合频率处伴有明显的边频带。研究结果可为齿轮系统转子裂纹故障的监测与诊断提供理论基础。     

带有齿根裂纹故障的齿轮传动系统非线性动力学模型研究

在考虑齿面摩擦、时变啮合刚度、传递误差和质量偏心的情况下,利用集中质量法及牛顿定律建立了齿轮传动系统非线性振动微分方程.通过时变啮合刚度仿真了齿根裂纹故障,进而建立了具有齿根裂纹的非线性动力学故障模型.该模型在计算摩擦力时,考虑了载荷在啮合区的动态分配以及利用齿轮副的检验标准与公差值来确定齿轮副的传递误差.模型数值解的结果与故障特征的规律相符,为频谱机理的分析及故障特征的提取提供了有力的理论依据.     

裂纹故障对斜齿轮时变啮合刚度及振动响应的影响分析

以含裂纹故障的斜齿轮传动系统为研究对象,结合轮齿接触、弯曲、剪切、轴向压缩及基体弹性变形,提出了含裂纹故障斜齿轮副时变啮合刚度修正算法,并通过有限元法验证了算法的正确性,而后分析了不同长度、深度、角度等裂纹参数对斜齿轮啮合刚度的影响规律。在此基础上,综合考虑齿轮时变啮合刚度、静态传动误差、轴承支撑刚度及齿轮转子陀螺力等因素,基于轴系单元法建立了单级裂纹故障斜齿轮传动系统耦合动力学模型,采用Newmark-β法对系统动态特性进行分析,研究了裂纹参数对系统振动响应的影响。结果表明,随着裂纹深度及长度的增加,齿轮副啮合刚度有较大幅度的减小,系统时域响应中存在周期性冲击现象,频域响应中出现了以啮合频率为中心的调制边频带,研究结果可为含裂纹齿轮传动故障诊断提供理论依据。     

变工况下裂纹故障直齿轮副振动特性分析EI北大核心CSCD

针对齿根裂纹齿轮副的故障检测,常利用采集齿轮箱振动信号进行分析评估齿轮副的健康状态,但在对故障齿轮副进行振动故障检测过程中,因为齿轮副的转速误差以及负载转矩波动及其他非稳定工况,使得齿轮副运行并不处于理想状态,此对齿轮副振动信号影响较大,使之难以分辨齿轮副振动的特征频率。为此根据势能法建立齿轮副齿根裂纹模型,推导齿轮副发生局部故障后其时变啮合刚度计算解析式,对变工况下齿轮副振动非平稳信号进行短时傅里叶变换,分析在变工况情形下齿轮副的振动特性。研究结果表明:在稳定工况下,齿轮副的振动幅值随转速和负载转矩增加而增加,其边频带分布也随之呈现出一定规律。在非稳定工况下,利用短时傅里叶变换后,发现齿轮箱振动时域和振动频域都出现明显的振动冲击,频域中相邻冲击峰的间隔反映齿轮副的转速误差,其主要频率的分布和幅值也可反映齿轮副运行过程中的转速和转矩负载的波动。同时,在非稳定工况下所得到的结论与齿轮副在稳定工况下运行所得到的结论相一致,皆为齿轮副的振动幅值随转速和负载转矩增大而增大。     

双齿根裂纹下的齿轮啮合刚度劣化特性研究

为研究相邻双齿根裂纹故障下的直齿轮时变啮合刚度劣化特性,根据直齿轮啮合原理以及时变啮合刚度的变化特性,采用具有较高计算精度的势能法,对不同工况下的双齿根裂纹故障区间刚度以及双故障齿的双齿啮合周期刚度劣化特性进行仿真计算分析。结果表明,两故障齿的最大裂纹深度对故障区间刚度劣化率的影响占主导地位;在双故障齿的双齿啮合周期中,最先啮入的故障齿裂纹深度对该区间刚度劣化率的影响占主导地位。研究结论揭示直齿轮双齿根裂纹故障刚度劣化过程,可为齿根裂纹故障诊断与在线监测提供理论基础和指导。     

波动负载对齿轮系统振动特性及边频调制影响研究

齿轮传动系统在工作时常承受复杂多变的外部波动载荷,导致轮齿啮合特性和系统振动响应频率特征复杂。基于时变啮合刚度的能量法合成模型,建立考虑系统扭振和横振响应影响的时变啮合刚度动态修正模型。建立单级齿轮传动系统的弯扭耦合模型,用Newmark法求解系统的振动响应。利用啮合刚度动态修正模型和齿轮系统弯扭耦合模型,通过数值算例分析波动负载对啮合刚度和系统振动响应的影响。结果表明,在波动负载作用下,啮合刚度和系统振动响应均存在明显的以波动负载频率为调制频率的边频调制现象,且被调制的中心谐波频率越高,调制现象越明显;外部波动负载的幅值越大,啮合刚度和系统振动响应的调制现象越明显,且当波动负载幅值较小时,表现为窄带调频和调幅的叠加,啮合频率两侧仅各有一条明显的边频谱线。     

齿轮传动系统断齿故障的机理研究

研究了含断齿故障的4自由度齿轮系统的动力学机理。考虑了断齿故障会引起齿轮系统微小的不平衡,及断齿故障对系统啮合刚度的影响,综合建立了齿轮—转子—轴承模型。数值仿真了故障信号,并通过时域图、相轨迹、Poincaré截面图及频谱分析研究了断齿故障引起的响应,及断齿故障的演化对系统动力响应的影响。最后实验模拟了齿轮断齿故障,通过实测振动信号的振动特征能够验证理论分析的结果,从而说明断齿故障理论模型的合理性,能为齿轮系统断齿故障的诊断提供理论依据。     

基于小波包与倒频谱分析的风电机组齿轮箱齿轮裂纹诊断方法

为实现风电机组齿轮箱及时有效地监测和维护,提出基于小波包与倒频谱分析的风电机组齿轮箱齿轮裂纹诊断方法。该方法针对齿轮裂纹振动信号为转速频率对啮合频率及其倍频调制的特点,利用小波包分解来识别振动信号中的故障特征,通过小波包频带能量监测得到故障部位的啮合频率范围;考虑到倒频谱可以分离和提取难以识别的密集调制信号的周期成分,基于倒频谱识别故障部位的转速频率,综合利用两种频谱分析方法得到的啮合频率和转速频率,能诊断故障部位和类型。实验研究表明,该方法能精确地诊断齿轮裂纹故障,并可以实现对风电机组齿轮在复杂环境中退化状态的监测,预防断齿等重大故障的发生。     

An improved time-varying mesh stiffness algorithm and dynamic modeling of gear-rotor system with tooth root crack

When a tooth crack failure occurs, the vibration response characteristics caused by the change of time-varying mesh stiffness play an important role in crack fault diagnosis. In this paper, an improved time-varying mesh stiffness algorithm is presented. A coupled lateral and torsional vibration dynamic model is used to simulate the vibration response of gear-rotor system with tooth crack. The effects of geometric transmission error (GTE), bearing stiffness, and gear mesh stiffness on the dynamic model are analyzed. The simulation results show that the gear dynamic response is periodic impulses due to the periodic sudden change of time varying mesh stiffness. When the cracked tooth comes in contact, the impulse amplitude will increase as a result of reductions of mesh stiffness. Amplitude modulation phenomenon caused by GTE can be found in the simulation signal. The lateral–torsional coupling frequency increases greatly within certain limits and thereafter reaches a constant while the lateral natural frequency nearly remains constant as the gear mesh stiffness increases. Finally, an experiment was conducted on a test bench with 2 mm root crack fault. The results of experiment agree well with those obtained by simulation. The proposed method improves the accuracy of using potential energy method to calculate the time-varying mesh stiffness and expounds the vibration mechanism of gear-rotor system with tooth crack failure.     

应用Hilbert变换和ZFFT提取变速器齿轮故障特征

变速器故障齿轮振动信号,调幅现象和调频现象同时存在,其频谱中包括啮合频率及其谐波、调制产生的耦合频率。Hilbert变换无法提供足够高的频率分辨率解调低频调制信号,为此提出复调制细化谱分析方法。通过变速器齿轮故障模拟实验,采集齿轮正常、轻微磨损和严重磨损时的稳态振动信号,对其进行Hilbert变换得到信号的包络,对包络信号进行复调制细化谱分析,得到齿轮轴转频基波及其谐波幅值。随着齿轮磨损程度的增加,齿轮轴转频基波及其谐波幅值明显增大,可作为齿轮磨损故障特征参数。     

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平均得到复合切片谱,进而提取出齿轮的故障特征。仿真和实验信号表明:在低信噪比条件下,频谱编辑与调制信号双谱相结合的方法能够有效抑制谐波信号以及白噪声的干扰,提取出故障特征,实现齿轮裂纹故障诊断。     

Analytical model for mesh stiffness calculation of spur gear pair with non-uniformly distributed tooth root crack

Gear tooth crack is likely to happen when a gear transmission train is working under excessive and/or long-term dynamic loads. Its appearance will reduce the effective tooth thickness for load carrying, and thus cause a reduction in mesh stiffness and influence the dynamic responses of the gear transmission system, which enables the possibility for gear fault detection from variations of the dynamic features. Accurate mesh stiffness calculation is required for improving the prediction accuracy of the dynamic features with respect to the tooth crack fault. In this paper, an analytical mesh stiffness calculation model for non-uniformly distributed tooth root crack along tooth width is proposed based on previous studies. It enables a good prediction on the mesh stiffness for a spur gear pair with both incipient and larger tooth cracks. This method is verified by comparisons with other analytical models and finite element model (FEM) in previous papers. Finally, a dynamic model of a gear transmission train is developed to simulate the dynamic responses when cracks with different dimensions are seeded in a gear tooth, which could reveal the effect of the tooth root crack on the dynamic responses of the gear transmission system. The results indicate that both the mesh stiffness and the dynamic response results show that the proposed analytical model is an alternative method for mesh stiffness calculation of cracked spur gear pairs with a good accuracy for both small and large cracks.     

基于MODWPT的Hilbert谱及其在齿轮故障诊断中的应用

在对基于最大重叠离散小波包变换(Maximal overlap discrete wavelet packet transform,简称MODWPT)的Hilbert谱方法进行介绍的基础上,将基于MODWPT的Hilbert谱应用于齿轮故障诊断当中。采用MOWDWPT可将多分量的复杂信号分解为若干个瞬时频率和瞬时幅值具有经典物理意义的单分量之和,然后求出各个单分量信号的瞬时频率和瞬时幅值,再进行组合便可以得到原始复杂信号完整的时频分布。对具有裂纹和断齿的齿轮故障振动信号的分析结果表明,基于MODWPT的Hilbert谱可以有效地提取齿轮振动信号的故障特征。     

Dynamic simulation of spur gear with tooth root crack propagating along tooth width and crack depth

Gear tooth crack will cause changes in vibration characteristics of gear system, based on which, operating condition of the gear system is always monitored to prevent a presence of serious damage. However, it is also a unsolved puzzle to establish the relationship between tooth crack propagation and vibration features during gear operating process. In this study, an analytical model is proposed to investigate the effect of gear tooth crack on the gear mesh stiffness. Both the tooth crack propagations along tooth width and crack depth are incorporated in this model to simulate gear tooth root crack, especially when it is at very early stage. With this analytical formulation, the mesh stiffness of a spur gear pair with different crack length and depth can be obtained. Afterwards, the effects of gear tooth root crack size on the gear dynamics are simulated and the corresponding changes in statistical indicators – RMS and kurtosis are investigated. The results show that both RMS and kurtosis increase with the growth of tooth crack size for propagation whatever along tooth width and crack length. Frequency spectrum analysis is also carried out to examine the effects of tooth crack. The results show that sidebands caused by the tooth crack are more sensitive than the mesh frequency and its harmonics. The developed analytical model can predict the change of gear mesh stiffness with presence of a gear tooth crack and the corresponding dynamic responses could supply some guidance to the gear condition monitoring and fault diagnosis, especially for the gear tooth crack at early stage.     

基于双树复小波和奇异差分谱的齿轮故障诊断研究

针对故障齿轮振动信号的非平稳特征和包含强烈噪声,很难提取故障特征频率的情况,提出了基于双树复小波和奇异差分谱的故障诊断方法。首先将非平稳的故障振动信号通过双树复小波分解为几个不同频段的分量;由于噪声的影响,从各个分量的频谱中难以准确地得到故障频率。然后对包含故障特征的分量构建Hankel矩阵并进行奇异值分解,求奇异值差分谱曲线,确定奇异值个数进行SVD重构降噪,由此实现对故障特征信息的提取。最后再求希尔伯特包络谱,便能准确地得到故障频率。实验结果和工程应用表明,该方法可以有效地提取齿轮的故障特征信息,验证了方法的可行性和有效性。     

Fault mode analysis and detection for gear tooth crack during its propagating process based on dynamic simulation method

Gearbox is one of the most important parts of rotating machinery, therefore, it is vital to carry out health monitoring for gearboxes. However, it is still an unsolved problem to disclose the impact of gear tooth crack fault on gear system vibration features during the crack propagating process, besides effective crack fault mode detection methods are lacked. In this study, an analytical model is proposed to calculate the time varying mesh stiffness of the meshing gear pair, and in this model the tooth bending stiffness, shear stiffness, axial compressive stiffness, Hertzian contact stiffness and fillet-foundation stiffness are taken into consideration. Afterwards, the vibration mechanism and effects of different levels of gear tooth crack on the gear system dynamics are investigated based on a 6 DOF dynamic model. Then, the crack fault vibration mode is studied, and a parametrical-Laplace wavelet method is presented to describe the crack fault mode. Furthermore, based on the maximum correlation coefficient (MCC) criterion, the optimized Laplace wavelet base is determined, which is then designed as a health indicator to detect the crack fault. The results show that the proposed method is effective in fault diagnosis of severe tooth crack as well as the early stage tooth crack.