基于增量谐波平衡法的复合行星齿轮传动系统非线性动力学

建立了包含时变啮合刚度、齿侧间隙与综合啮合误差的Ravigneaux式复合行星齿轮传动系统纯扭转动力学模型。运用增量谐波平衡法对系统运动微分方程组进行求解,得到系统的基频稳态响应。研究了时变啮合刚度、外部激励、齿侧间隙等参数的变化对系统动力学特性的影响。研究结果表明,间隙的存在使得复合行星齿轮系统的频响曲线出现了幅值跳跃与多值解等典型非线性特征,系统参数的共同作用使得复合行星齿轮系统出现了丰富的非线性动力学行为。利用本文的方法可以获得系统任意精度的近似解,为控制系统的振动与噪声,实现复合行星齿轮传动系统动态设计奠定基础。     

具有分数导数本构关系的粘弹性浅拱的非线性动力学行为

利用分数导数本构模型描述材料的粘弹性特性,建立了粘弹性浅拱在横向荷载作用下的动力学方程。利用Galerkin截断法并结合边界条件分别得到了一阶和二阶Galerkin系统的控制微分方程。通过数值计算,分析了简谐激励下一阶Galerkin系统的非线动力学行为。研究表明:随着外激励幅值的变化,粘弹性浅拱系统可以通过倍周期分岔或阵发性两条路径进入混沌;固定外激励幅值、频率以及阻尼系数等状态参数,不同初始条件下,系统可以出现多周期解共存、周期解与混沌解共存的现象。     

考虑修形的斜齿轮系统非线性激励与动力学特性研究

斜齿轮的啮合刚度与轮齿误差的求解是三维空间问题,其修形后的啮合刚度计算方法不同于直齿轮,而传统解析方法在计算斜齿轮啮合刚度时没有考虑斜齿轮啮合线和啮合位置的三维空间位置,无法准确得到修形后的斜齿轮系统啮合刚度激励与误差激励。建立综合考虑齿廓修形和齿向修形的刚度与误差非线性耦合激励模型,研究不同齿廓修形参数与齿向修形参数对斜齿轮啮合刚度以及系统动力学特性的影响规律;以系统振动加速度幅值最小为优化目标,确定斜齿轮系统的最佳修形值,利用数值方法得到斜齿轮系统的振动加速度幅频响应曲线,研究结果发现:选取的最佳修形参数可有效降低斜齿轮齿数交替区啮合刚度的波动,大幅度降低共振点附近的振动加速度幅值;最后通过建立的齿轮传动系统实验平台进行系统动力学特性实验研究,验证了理论模型及分析结果的正确性。     

行星齿轮传动系的周期运动及其稳定性

本文主要研究了间隙行星齿轮非线性传动系的周期运动及其稳定性。针对PNF方法在求解非线性动力系统时存在的两点缺陷,即研究对象必须光滑和迭代初始点要求距离周期解足够近,提出了改进措施使之能够适应本文所研究的间隙行星齿轮传动系统的周期轨道的求解以及判稳。改进后的PNF方法对算例的计算结果和直接数值积分结果的吻合证明了改进措施的有效性。采用改进后的PNF方法研究了行星齿轮系统在一组给定参数下共存的周期运动,并判断了各共存周期运动的稳定性;通过延续判断不同转速下系统周期解的稳定性,研究了行星齿轮传动系统的运动状态随无量纲转速的分岔特性。结果发现,行星齿轮非线性传动系统在某些参数组合下可以共存几个稳定或者是不稳定的周期解;转速的变化可以使行星齿轮系统通过倍周期分岔的形式最终通往混沌。     

两级定轴齿轮断齿故障的非线性耦合特性研究

为研究两级齿轮传动系统断齿故障的非线性耦合特性,建立了包含时变啮合刚度、齿侧间隙和综合啮合误差等非线性因素的单级及两级齿轮量纲一动力学方程。利用数值方法对建立的非线性微分方程进行求解,获得系统的分岔图、相图及Poincaré截面,对比研究两系统中一级齿轮随激励频率变化的分岔特性及断齿故障下的故障特性。研究结果表明:耦合特性使两级齿轮系统的周期运动区间增加,幅值亦增加,混沌区间缩短并延迟,对混沌起到抑制作用;断齿故障使单级齿轮系统突跳点增加,同时阵发周期运动出现变化,且变化趋势不确定,对于两级齿轮系统仅使阵发周期运动幅值增加。     

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。     

计及空间温度效应的齿轮系统动力学行为研究

在轨航天器齿轮传动机构频繁进出地球阴影区时,因温度交替变化会引起齿侧间隙改变,导致传动精度下降,甚至会造成卡死或传动中断。以单自由度直齿圆柱齿轮传动系统为对象,综合考虑时变啮合刚度、综合传递误差及齿侧间隙等因素的基础上,进一步引入空间特殊环境下的温度交变效应,建立了适用于空间环境的齿轮系统非线性动力学模型;采用4阶~5阶变步长Runge-Kutta算法,结合相图、Poincare映射图和分岔图,分别对考虑和不考虑温度交变效应的系统动力学行为进行了求解和分析,并定量研究了温度交变幅值和频率对齿轮系统动力学的影响。结果表明,环境交变温度对齿轮系统动力学影响较大,使得系统各工况都有不同程度向混沌演化的趋势,且交变的幅值和频率对系统解结构的影响呈现一定规律,相关结论对特殊环境齿轮系统的设计与匹配具有一定的指导意义。     

微线段齿轮系统动力学特性分析

利用有限元法求出了微线段齿轮的时变啮合刚度,考虑微线段齿轮齿廓的特殊性,建立了单自由度微线段齿轮传动系统的动力学模型,模型中考虑了综合误差、时变啮合刚度以及齿侧间隙。通过数值仿真分析了比对两种齿轮系统在不同转速、载荷下的动力学响应,并指出了系统的亚谐共振及其幅值跳跃特性。对比分析了两种齿轮的分叉特性,结果表明,微线段齿轮相比普通渐开线齿轮具有更好的稳定性,其系统的混沌转速区间小,在中高速重载时其系统振动幅值小,传动更加平稳。     

含时滞反馈控制的直齿圆柱齿轮主共振分析

为了减小直齿圆柱齿轮系统由于外载荷波动和时变啮合刚度引起的振动,建立了直齿圆柱齿轮的时滞反馈减振动力学模型,并利用多尺度法对时滞反馈齿轮传动系统进行求解,获得了齿轮系统主共振频率响应方程,通过分析比较载荷波动、啮合刚度波动和时滞反馈控制参数对主共振的影响,可以得出:齿轮系统存在的载荷波动和啮合刚度波动都会导致齿轮系统主共振不稳定;合理匹配的时滞控制参数能够使主共振快速收敛到稳定解,反之可能导致系统振动加剧,使系统稳定性变差。     

机车转子非线性系统的动力学分析

随着机车速度的提高,对机车的运行安全性和稳定性提出了更高的要求。主要研究了非线性双转子连续-质量转子系统的动力学模型,综合考虑转子支撑、齿轮啮合刚度等复合非线性因素影响。基于哈密尔顿最小势能原理,建立连续-质量非线性转子系统的动力学模型,对系统进行无量纲化处理,并求解了固有振动频率及振型。采用MR-K迭代法求解强非线性转子系统的数值解。定量分析在支撑刚度、阻尼及其齿轮刚度参数作用下,转子系统的幅频响应变化。结果表明:复杂边界条件下,系统的固有频率对传动系统振动响应影响较明显。当齿面磨损及间隙变化时,齿轮啮合刚度变大,转子系统在固有频率处位移显著增大。轮轨激励的变化,引起系统从动轴横向弯曲幅值变大。     

The influence of neglecting small harmonic terms on estimation of dynamical stability of the response of non-linear oscillators

The effects of neglecting small harmonic terms on estimation of dynamical stability of the steady state solution determined in the frequency domain are considered in this paper. For that purpose, a simple single-degree-of-freedom piecewise linear system excited by a harmonic excitation is analyzed. In the time domain, steady state solutions are obtained by using the method of piecing the exact solutions (MPES) and in the frequency domain, by the incremental harmonic balance method (IHBM). The stability of the solutions obtained in the frequency domain by IHBM is determined by using Floquet–Liapounov theorem and by digital simulation of the corresponding perturbed motion. Received 20 July 1998     

基于增量谐波平衡方法的Spar平台垂荡纵摇耦合内共振响应研究

针对经典的Spar平台垂荡纵摇耦合运动问题,为解决传统小参数摄动方法和时间步进分析方法的不足,提出将增量谐波平衡方法(Incremental Harmonic Balance Method,IHBM)应用于研究其内共振响应特性。根据Floquet稳定性分析理论,对周期解的稳定性和分叉特性进行分析;在此基础上,通过将该方法与增量弧长法相结合,实现了快速、连续获得Spar平台垂荡纵摇耦合周期运动响应的目的;将IHBM计算结果与时域模拟和多尺度法计算结果进行对比,验证了该方法的准确性和高效性,该方法能够准确预测当波浪激励力频率满足一定条件,系统发生内共振时引起的纵摇不稳定运动现象。对于垂荡纵摇耦合产生的概周期运动,该方法结合Floquet理论能准确预测其发生的参数区间,从而为该周期运动的分析提供良好的基础。     

齿轮箱声固耦合系统噪声辐射研究

综合考虑齿轮时变啮合刚度及齿轮误差的影响建立了齿轮系统动力学模型,计算得到了齿轮系统动载时域历程。建立了齿轮箱声固耦合系统模型,采用边界元法对其噪声辐射进行求解,得到了齿轮箱噪声谱及各板面对声场总声压的贡献度。依据板面贡献度计算结果,对齿轮箱结构进行适当改进,对结构的改进及结构阻尼对降噪效果做出了分析,就不同齿轮类型对齿轮箱噪声辐射的影响进行了讨论,为齿轮箱的设计提供了理论依据。     

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.     

基于力耦合的非谐振单元组成的超声变幅器设计

传统的超声振动系统全谐振设计方法要求组成超声振动系统的各个单元有相同的谐振频率,各个组成单元的结构尺寸由谐振频率确定,而超声珩齿系统中的齿轮结构尺寸是由它的使用要求决定,是非谐振单元,不能用全谐振理论设计,本文采用力耦合方法,将齿轮简化为环盘,将它和变幅杆组合并联合建立动力学方程,实现了非谐振单元组成的超声变幅器的设计。     

Failure Analysis of a Diesel Engine Gear System Consisting of Camshaft and Crankshaft Gears

A failure investigation was conducted on a diesel engine gear system consisting of a driven camshaft and drive crankshaft gears that were used in a truck. The gears are made from a nitrided 42CrMo steel. Adjacent teeth fracture and plastic deformation regions appeared on the gears after a 400 h run test of the gear system. Fractography indicates that fatigue fracture is the dominant failure mechanism for the gear teeth. Although the appearance of needle-like nitrides in the nitrided layer and the narrow depth of the compound layer may decrease the fatigue strength of the camshaft gear, these do not suffice to lead to the premature fracture of the gear teeth. Geometrical analysis of the gears was performed and compared with an analysis of unfailed gears that had experienced a run test for 1800 h. The comparison reveals that the small fillet radius at the root area of the camshaft gear concentrated the stresses and is mainly responsible for fatigue fracture of the teeth. The camshaft gear is the component that initiated trouble in the gear system. The appearance of severe plastic deformation on the gear faces is caused by the fractured teeth crushing the teeth faces and being embedded in the grooves between teeth.     

Backlash effect on dynamic analysis of a two-stage spur gear system

Gearbox dynamics are characterized by a periodically changing stiffness due to multiple teeth contacts. In real gear systems, a backlash also exists that can lead to a loss in contact between the teeth. Due to this loss of contact, the gear has piecewise linear stiffness characteristics. This paper examines the effect of backlash in the two-stage gear system. A purely torsional gear system is formed by three shafts connected to each other by two spur gear pairs. Using standard methods for nonlinear systems (Newton-Raphson algorithm), the dynamic behavior of a gear system with backlash is examined. Amplitude jumps in systems due to backlash are observed.     

Effects of gear center distance variation on time varying mesh stiffness of a spur gear pair

Gear center distance variation is one of the most common defects of gear transmission systems. The changes in the gear center distance as well as other faults (e.g. tooth crack, pitting) have a direct influence on the Time Varying Mesh Stiffness (TVMS) which further modifies gear vibration behaviors. Accurately estimating gear TVMS under fault conditions is crucial in gear vibration dynamic simulation. Common methods used to evaluate TVMS are generally based on the assumption that the gear pair is perfectly mounted and that all mesh points are at their theoretical positions. This assumption prevents these methods from modeling deviations in gear center distance. To address this shortcoming, this paper proposes a new gear mesh kinematic model that can evaluate the actual contact positions of tooth engagement with time varying gear mesh center distance. With the proposed kinematic model, the actual TVMS of both healthy and cracked gear teeth are computed under conditions of perfect mounting, constant gear center distance deviation, and also time-varying gear center distance. Numerical simulations indicate that gear center distance variation has a significant effect on gear TVMS. Comparison between the effect of multiple faults and summed individual effects on TVMS indicates that the TVMS modification due to multiple-faults do not appear to combine in a linear manner. The proposed model for actual TVMS enables gear system dynamic models to be used to study the effects of assembly errors, gear run-out errors, shaft bending, and bearing deformation on the vibration behavior of gear transmission systems.     

多齿轮耦合复杂转子系统的振动特性分析

本文探讨了多对齿轮耦合对齿轮转子系统动力学特性的影响程度,以压缩机转子系统为例,对整个耦合系统进行了安全校核。首先,基于有限元法,建立了通用的弯—扭—轴—摆斜齿轮耦合动力学分析模型,此模型中考虑了啮合刚度、方位角、啮合角、螺旋角以及主动轴转动方向对齿轮啮合刚度矩阵的影响;接着,对系统进行了固有特性分析,得到了系统的临界转速和安全裕度表;然后,基于模态叠加法,对系统进行了不平衡响应分析,对比了考虑齿轮啮合前后系统各位置处的不平衡响应变化曲线。研究结果表明,对于多对齿轮啮合的系统,齿轮间的耦合使系统之间的振动强烈,必须考虑齿轮耦合的影响,并且要结合固有特性以及瞬态响应分析来判断临界转速和振动峰值的大小。     

Parametric relationship between hypoid gear teeth and accurate face-milling cutter

The cutter systems of hypoid gear cutting machines contain groups of inside and outside blades. In these cutter systems, the side cutting edges of the blades machine the convex and concave gear teeth while rotating about the cutter rotation axis. The side cutting edges lay on the rake face formed through the blade, rake, and relief angles; hence, the normal cross-section of the cutter swept surface forms hyperboloid gear teeth. Using the accurate geometry of the cutter system, a relationship between the pressure and spiral angles of the gear tooth and the parameters of the cutter system is developed for the FORMAT machining of a hypoid gear. A new parameterization of the gear tooth surfaces is introduced to determine these angles for the accurate gear tooth by the accurate cutter system. A numerical example with different cutter systems and blade parameters is presented, demonstrating the effects of rake and relief angles over the pressure and spiral angles on mean point projections and gear tooth surface. Finally, the change in pressure and spiral angles with respect to the rake and relief angles are plotted, and the results are analyzed. Finally, it is concluded that the pressure and spiral angles are changed up to a few seconds of a degree in the operating area of the tooth with the change in the back and side rake angles. The side relief angle exhibited little or no effect over the geometry of the gear tooth.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-019-00286-x