Dynamics and Fatigue Analysis of Planetary Gear Trains under Random Loading

行星齿轮系（PGT）广泛用于工业和许多其他应用中。在一些应用中，PGT所经受的载荷是随机的/随机的。PGT被用作传输单元并且经受随机载荷的两个代表性场景包括风能工业中的风力涡轮机和石油和天然气工业中的定向钻井。这些系统中由振动引起的疲劳问题是工业中的一个突出问题，并且具有巨大的经济后果。然而，振动应力的随机性在很大程度上阻碍了准确的疲劳预测和适当的疲劳管理。* 拟议的研究旨在系统地研究PGT在随机载荷下的动力学，并开发有效的疲劳预测方法。基于上述两种情况，所有PGT共同的内部激励和因不同应用而变化的外部激励将被建模为随机过程。将进行实验以表征目前知之甚少的钻井中的外部激励。然后，统计的响应，包括位移，速度，应力和应变，可以解决与数值和解析方法。这些统计信息构成了进一步疲劳预测的基础。预计通过这项研究，风力涡轮机和钻井中PGT的可靠性和疲劳寿命都将得到提高。长期目标是在一般随机背景下开发PGTs随机动力学的理论框架;因此，该方法和算法可以应用于更广泛的应用并使其受益，例如近海工程和陆地车辆中的应用。 *** **

Planetary Gear Trains (PGTs) are widely used in industry and many other applications. In some of the applications, the loads to which the PGTs are subjected are random/stochastic. Two representative scenarios where PGTs are used as a transmission unit, and subjected to random loads include wind turbines in wind energy industry and directional drilling in oil and gas industry. Fatigue caused by the vibration in these systems is a outstanding issue in the industries, and has huge economical consequence. However, the random nature of the vibration stresses largely hinders accurate fatigue prediction and proper fatigue management. ***The proposed research intends to systematically investigate the dynamics of PGTs under random loads, and develop effective fatigue prediction methods. Based on the two cases above, the internal excitations which are common to all PGTs and the external excitations which vary for different applications will be modeled as random processes. Experiments will be carried out to characterize the external excitation in drilling for which little is known at present. Then the statistics of the responses, including displacement, velocity, stresses and strains, could be solved for with numerical and analytic methods. These statistic information constitutes the basis for further fatigue prediction. It is expected that, through this proposed research, the reliability and fatigue life of PGTs in both wind turbines and drilling could be improved. The long term goal is to develop a theoretical framework for random dynamics of PGTs in general random context; thus, the method and algorithms can be applied to and benefit broader applications, such as applications in off-shore engineering and land vehicles.  *** **