含齿根早期裂纹损伤的行星齿轮箱故障机理研究

Investigation of Fault Mechanism of a Planetary Gearbox with Incipient Tooth Crack

行星齿轮箱中齿根早期裂纹损伤的故障特征微弱,导致其难以被识别.为揭示齿根早期裂纹的故障机理,采用集中参数法建立计入裂纹损伤效应的行星齿轮箱传动-结构耦合非线性动力学模型.首先,基于势能法建立含齿根裂纹损伤的齿轮副啮合刚度与传动误差计算模型,通过刚度激励函数与位移激励函数将裂纹损伤的效应纳入行星传动系统的非线性动力学模型,进而求解行星传动系统的振动响应,结果表明内、外传动支路之间的传动误差差异导致各支路载荷分配不均.其次,采用ANSYS Workbench建立箱体结构的有限元模型.将行星传动系统中太阳轮、行星架以及内齿圈的支承反力施加于箱体结构的相应轴承座处,并通过窗函数计入行星架旋转对信号的调制效应以获取行星齿轮箱的振动信号;通过对箱体振动信号的频谱分析,提取了行星齿轮箱齿根早期裂纹损伤的故障特征.最后,搭建动力传动故障模拟实验台,对存在齿根早期裂纹损伤的行星齿轮箱进行了振动测试.仿真信号与实测信号基本一致,表明所建行星齿轮箱传动-结构耦合动力学模型能准确揭示行星齿轮箱齿根早期裂纹损伤的故障机理.行星齿轮箱中齿根早期裂纹损伤的故障特征表现为以啮合频率为中心、故障特征频率的分数倍频及行星架转频为间隔的调制边带.

Identifying weak fault features caused by an incipient tooth crack in a planetary gearbox is difficult.To characterize the fault features of incipient tooth cracks in a planetary gear train,this paper established a transmissionstructure-coupled nonlinear dynamic model that includes the effect of crack damage with lumped parameter method.Based on potential energy method,a mathematical model of time-varying mesh stiffness and transmission error was established.The effect of crack damage was incorporated into the nonlinear dynamic transmission model through stiffness excitation and displacement excitation functions.Furthermore,the vibration response of the planetary transmission system was solved,indicating that the difference in transmission error between internal and external transmission branches is an important cause of non-uniform load distribution.Moreover,a finite element model of the gearbox was built in the ANSYS Workbench environment.After applying the reaction forces of the sun gear,the carrier and the ring gear on the bearing housings of the gearbox,and including the modulation effect of the carrier rotation with a window function,frequency analysis can be conducted on the simulated vibration signals to identify the damage mode of the tooth crack.Finally,a test rig of the planetary gearbox was constructed,based on which a set of vibration tests were conducted to detect the tooth crack.The consistencies of the simulated and experimental signals prove that the proposed transmission-structure-coupled dynamic model can accurately reveal the fault mechanism of the planetary gearbox with an incipient tooth crack.The fault features of this planetary gearbox demonstrate a set of modulated sidebands around the mesh frequency.Additionally,the intervals of the modulated sidebands are the fractional frequencies doubling of the fault frequency and carrier rotation frequency.